Good evening and welcome to the National Archives, the William G. McGowan Theater. I'm David Ferriero, the Archivist of the United States, and I'm pleased you could join us for this evening's program, whether you're here in the theater with us or joining us on Facebook or YouTube. To keep informed about events coming up here in the National Archives next year, check our website, archives.gov, or sign up at the table outside the theater to get email updates. You'll also find information about other National Archives programs and activities, and a great way to get more involved with the National Archives is to become a member of the National Archives Foundation. The Foundation supports our education and outreach activities, and you can check out their website, archivesfoundation.org, to learn more about them and join online. And we have in the audience with us the Executive Director, the President of the National Archives Foundation Board, Governor Jim Blanchard, here in the front row with his lovely wife, Janet. Nice to have you both with us. And a little-known secret that I keep telling everyone about, no one has ever been turned down for membership in the National Archives Foundation. The book we celebrate tonight, the American Story Conversations with Master Historians, grew out of the congressional dialogues on Great American Series at the Library of Congress, which David Rubenstein launched in 2013. Conversations with biographers and historians about significant figures in American history. Although these sessions were open only to members of Congress, this book gives us all an opportunity to learn about great Americans from our most renowned historians. You all know David as the father of patriotic philanthropy, wander around the district and beyond, and you'll see evidence of his generosity everywhere you turn. The Smithsonian Institution, the Library of Congress, Mount Vernon, Monticello, Arlington House, and the Washington Monument to name a few, and he's a generous supporter of the National Archives and its foundation and received the Foundation's Records of Achievement Award in 2011. Our ground floor exhibit in the Rubenstein Gallery Records of Rights features the 1912-97 Magna Carta, which he has loaned to the National Archives for public display, and the Public Faults Exhibition displays a rare stone engraving of the Declaration of Independence, also courtesy of David Rubenstein. A native of Baltimore, David is co-founder and managing director of the Carlisle Group, a global alternative asset manager, a Magna Cum Laude graduate of Duke, Rubenstein graduated in 1973 from the University of Chicago Law School, where he was an editor of the Law Review. And after practicing law in New York, he served as chief counsel to the U.S. Senate Judiciary Committee, subcommittee on Constitutional Amendments, and during the Carter administration, David was deputy assistant to the president for domestic policy. After his White House service, he practiced law at a private firm in Washington and then co-founded the Carlisle Group in 1987. A star of Bloomberg Television, David has hosted five seasons of the Rubenstein Show, which explores leadership through conversations with the most influential people in their fields, without a note. Each of these interviews, he does off the top of his head. Joining David this evening, Taylor Branch is an American author and public speaker best known for his landmark trilogy on the Civil Rights era, America and the King Years. The trilogy's first book, Parting the Waters, America and the King Years, won the Pulitzer Prize in numerous other awards in 1989. Branch's 2009 memoir, The Clinton Tapes, wrestling history with the president, Chronicles, an unprecedented eight-year project gathering a sitting president's comprehensive oral history confidentially on tape in his cover story for the October 2011 issue of the Atlantic, the shame of college sports touched off continuing national debate. In 2009, he won an Emmy Award as executive producer for the 2018 HBO documentary King and the Wilderness, and about the final three years of Dr. King's life. H. W. Brands holds the Jack S. Blanton senior chair in history at the University of Texas, where he has taught since 2005. He's a member of various honorary societies, including the Society of American Historians and the Philosophical Society of Texas. He's a regular guest on national radio and television programs and is frequently interviewed by the American and foreign press. He's written 25 books, co-authored or edited five others and published dozens of articles. His articles have appeared in the New York Times, the Wall Street Journal, the Washington Post, the Atlantic and the Journal of American History. His writings have received critical and popular acclaim, the first American, and a traitor to his class were finalists for the Pulitzer Prize and the Los Angeles Times Prize. And J. Winnick is one of the nation's leading public historians. He is the author of the highly acclaimed work on the Civil War, April 1865, the month that saved America, which was turned into an Emmy Award-winning television special. He's also the author of the best-selling works, 1944, FDR in the year that changed history and the great upheaval America and the birth of the modern world, 1788-1800. He was the presidential historian for Fox News coverage of the last three historic presidential inaugurations and was also the historical advisor to the chairman of the National Geographic Networks. Until recently he was the inaugural historian in residence at the Council of Foreign Relations endowed by David Rubenstein. Before I turn the stage over to our speakers, I want you to know that generous David Rubenstein has graciously provided us with free autographed copies of the American story for each person in the audience this evening and they will be distributed by the National Archives Foundation staff in the Theater Lobby as you exit. Our panelists have contributed chapters to the book and are willing to add their signatures and limited copies of the panelists books will also be available in the Theater Lobby for purchase. The holidays are just a week away, so. And now, ladies and gentlemen, please welcome David Rubenstein, Taylor Branch, H.W. Branch, and J. Winnick. So thank you all for coming. As you heard, we have a very distinguished panel here of historians and I would say that I don't deserve to be on their stage because I'm not a distinguished historian but by the time I reached the age of 70 I wanted to have a book published by myself so they have between them I guess probably about 40 some books. I have one and I just came out and I'll just describe it one moment what it's about and then we'll talk about their books. It was my fear that because we are obsessed with STEM education, which is a good thing, but we are not teaching children and young adults much about history and civics anymore and the result is you get statistics that show things like three-quarters of Americans cannot name the three branches of government. One-third of Americans cannot name even one branch of government. Twenty-five percent of Americans believe that Larry Summers was the first treasury secretary, not the case. Thirty percent of Americans believe that the river that George Washington crossed during the Revolutionary War was the Rhine River, which is not even our country. And 10 percent of American college graduates, this is hard to believe, 10 percent of American college graduates believe that Judge Judy is a member of the United States Supreme Court, which is not yet the case. Think about this. If you, any naturalized citizens here, anybody that naturalized American, okay.  It used to be 14 years, but now it's five years. Then you take a test. It typically has a hundred questions. You have to pass 60 of them and get 60 right. They're questions like who was the first president of the United States and so forth. Ninety-one percent of the people who take that test, presumably with some studying, pass. The Woodrow Wilson Foundation recently did a survey of native-born Americans, gave them the same tests in all 50 states. In only one state, Vermont, put a majority of citizens who are native-born past that citizenship test, which shows you that we're not really teaching our native-born citizens very much about history and civics. One way I thought maybe I could add to something in that direction was trying to educate members of Congress who are passing the laws that are relevant to our society. I started six years ago a program to educate members of Congress a bit about history, not that they don't know a lot, but they can always learn more. Once a month for the last six years, I've hosted a dinner at the Library of Congress for members of Congress. We get 250 to 300 people, about half of them are members of Congress and then their guests. We interview distinguished authors like these authors, all of whom I've interviewed there. The book is really a compilation of some of the best of those interviews. Before I begin the interview, I'll just tell you about one interview that was not a historian. I wanted to have members of Congress know a little bit more about the Supreme Court. I asked the Chief Justice if he would let me interview him, and I know him from the Smithsonian Institution. He said yes. Since I began the interview, I said, well, Mr. Chief Justice, did you always want to be Chief Justice of the United States when you're little? He said no, I had no interest in that. Did you want to be an Associate Justice of the Supreme Court? No, I didn't want that either. Did you want to be a judge at all? No, I didn't want that either. Did you want to be a lawyer? No, I didn't want to be a lawyer either. But what did you want to be? All I wanted to be when I was growing up was a historian. I thought that was the greatest thing that I could do. I loved American history, and I just told my father that's all I want to do is write books about history. My father said, of course, these authors are much more distinguished than John's father thought John would be. He said, you'll never make any money doing that. You'll starve to death as a historian. Of course, these are more distinguished than John's father thought John would be. And John said, I don't really care. I don't care about starving to death. I don't really care about anything. I just want to write about American history. So his father said, OK, he went off to Harvard, and he majored in history. When he came back from a spring break, he got off at the airport in Boston, Logan Airport. He said to the cab driver, please take me to Cambridge. The cab driver said, well, are you a student at Harvard? Yes, I am. What are you majoring in? I'm majoring in history. The cab driver said, well, when I was a student at Harvard, that's what I majored in also. So anyway, let's talk about these. So Taylor Branch, Taylor, let me talk first about your epic civil rights work. You spent how many years on that? 24. 24. Now, halfway through it, did you ever say this is taking more time than I thought, and maybe it's not that easy to do? And their first book won the Pulitzer Prize, so would you say, why don't you just stop right there? You can't top that. Oh, no, I was obsessed and enthralled with finishing it. And I had a wife who took care of our health insurance. Right? Other than that, I didn't, you know, I wanted to keep going. It was a tremendous work. The Pulitzer Prize helped me with negotiations with the publisher, because before that it was pretty tough. How many pages was it? You wrote 30 pre-volumes, how many pages was it? About 2,200 pages, plus I don't know how many pages it was. So when you finished the last word of the third volume, do you say, I'm done with this subject or not? No. You've written another book since then about that. Well, I compressed it into a short book with lessons drawn from it. My rule was only storytelling, no essays, because I think people learn about race given our divisions, only when things are really personal, not when they're abstract. So my books are sprawling, and I did a short book that kind of draws from it, because teachers told me that my books were too fat. Martin Luther King, what was his real name at birth? It wasn't Martin. Michael. Michael King. Why did it get changed? Daddy King, in the teeth of the Depression, figured out ways to turn his bankrupt church into an economic juggernaut, such that in 1934 they sent him around the world, and his last stop was in Berlin, and he went to the home of Martin Luther, and was so full of himself that when he came home, he changed his name to Martin Luther King, and changed little Mike's name to Martin Luther King Jr. to fit. And did Martin Luther King Jr. always want to be a preacher, or did he want to be something else?  And if you were interested in making money, you became a preacher. What about private equity? You didn't mention that. No, he didn't mention private equity. But his father organized Ebenezer Church into kind of an insurance company, and the members were responsible for going out and collecting ties when they collected policies. So he was an economic force. Now, when Martin Luther King gave his famous speech on the Mall, why was he the last speaker that day? Well, nobody wanted to go after him, because they knew he was a good speaker. And was he the real leader of the civil rights movement then, or was he just one of the leaders? He was one of the leaders. He already had a preeminence in the way he could frame questions, frame the issue. But no, I mean, Roy Wilkins was head of the NAACP and Jim Farmer, they were jostling each other. So it is said that he stayed up the night before with a speechwriter to write that speech. And then when he was giving the speech, actually, Mahalia Jackson was behind him and saying, tell him about the dream, Martin, so he departed from the speech. Is that right? And most of it was extemporaneous? That is right. And the only parts that we remember were extemporaneous. Black preachers are a lot like jazz musicians. They have riffs that they do and they improvise. And he had improvised the I Have a Dream speech for two or three years and had given it. And people had heard snippets of it. But white people hadn't heard it that much. White people hadn't heard any speech by him very much. I mean, this is the only real, the mass meeting, this was a mass meeting, which was a distinctive institution for black people who didn't control any other institutions like TV networks or theaters. The mass meeting in a church was the way it communicated and made decisions. This is the only mass meeting that was ever on television. Why did President Kenny not speak at the March on Washington? Oh, gosh. They were terrified that it was going to be Armageddon. They canceled two Washington Senators games in advance, not just on the day of the March, but the next day because they figured, you know how hard it is to cancel a Major League Baseball game? They canceled the next day because they assumed they would still be cleaning it up. So there was a lot of fear about it. But after the speech was over, did President Kenny invite him and the others to come to the White House? And what did President Kenny say when he greeted Martin Luther King? I have a dream. That's good. Okay. So he knew a good line when he heard it. Okay. So, Bill, the book we talked about at the Library of Congress was, you've written 30 books, so I won't go through all 30 of them by now, but the one we talked about was Ronald Reagan. And as I recall, your thinking was that Ronald Reagan was very hard to get your hands around. In fact, his authorized biographer invented a character himself to go into that book. Do you have any comments about the difficulty of understanding Ronald Reagan? Why was he so difficult for people to understand in terms of what he really felt in his head? So this is where I differ with. Okay. I didn't think Reagan was that hard to understand in part because I didn't think he was especially complicated. Maybe I was missing something. But when I was actually, while I was doing research on the Reagan book, I was also touring to support our previous book. And I was giving an interview, a radio interview, and I think it was in Chicago. And while I was, we did the interview, and the interview lasted about an hour or so. And one of the stock questions toward the end of such an interview is, so what's your next project? And I said that I was working on Ronald Reagan. And so the host of the interview put his hand over the microphone. So I could hear, but the audience couldn't. He said, when we get off the air, I need to tell you something about Ronald Reagan. Okay. So I was very curious. And we go off the air, and I'm sitting there waiting, and he said, if you want to understand Ronald Reagan, you need to always keep in mind that he was the son of an alcoholic father. And when I heard this, I didn't know exactly how I was supposed to react. I didn't know if he thought that he was conveying information that no one else had, because everybody else had it. Reagan, by this time, had written two memoirs, and in both of the memoirs, he talks about his alcoholic father. And so I, not knowing what to say, I just didn't say anything and waited to hear more. And he said, this radio host said, I speak as the son of an alcoholic father. And I can tell you that it really causes you to have strong reservations about making emotional attachments, because the person who is the model for you, the one you want to be closest to, is one who is utterly unpredictable. So one day, you come home from school, and he is your best friend.  And the next day you wake up, and he's beating a living day life out of you. And so you just learn to keep people at a distance. So anyway, so I was very intrigued by this, and I didn't take his word for it on Reagan, but I looked for evidence Reagan in Reagan of this sort of thing. So to me, the interesting question was not sort of what made Reagan tick, because I didn't think he was that confident. To me, the question is what made Reagan successful, because Reagan was when he was a young man, when he was a child, when he was a young man, through most of his adult life, you never would have picked him out to be one of the two most important presidents of the 20th century. But he was, and that's the question for his biographer. Okay, so on Ronald Reagan, he started out as a new deal Democrat. He voted for Franklin Roosevelt as he liked to say four times. What converted him to being a conservative Republican? His support for Franklin Roosevelt in the new deal was really something that he essentially inherited. He was a legacy Democrat. He hadn't thought about politics much when he was young. He didn't make a positive decision to become a Democrat and support Franklin Roosevelt. His father got a job in one of the new deal agencies at a time when the family really needed the income. But what basically happened is Ronald Reagan started making some money, and he ascended in the tax brackets to the point where- And the tax bracket then was 90 percent- 90 percent on the last dollar you made. And he thought, well, this is a lot.  Well, certainly, certainly. And he did start thinking about politics. And so he thought, okay, and he also got a job working for the General Electric Corporation. He was a spokesman for GE, and he traveled the country speaking on behalf of all the good things that electricity can do for you and all the good things that American capitalism does for this country and the world. And it was then that he got his education in political economics. Now, it is said by some that he wasn't that ambitious that had Nancy Reagan not been his spouse. He would not have tried to run for governor or president. Do you think that's true? They certainly were a team. And Nancy had something to do with this sort of thing. I mean, I don't know if he had remained married to Jane Wyman. Now, he wouldn't have stayed in Hollywood because, and one of the reasons I got divorced was that her career was taking off and his was flat at Miami. And he just couldn't get any good roles. So he needed something else to do. By the way, was his hair died? Was his hair died? His barber swore that he couldn't see any different colored roots. And so I can't say he's barber. So in other words, it wasn't died. You don't know. It could be one of the best cover-ups in American political history. All right, Jay. Your book, let's talk about the first book that you wrote in 1944. The most significant year, you would say. FDR in your book goes through a lot of, he's lobbied a lot about trying to bomb the railroad tracks that lead to Auschwitz. And he ultimately decides not to do so. Did he really realize what was going on in Auschwitz and other concentration camps? And why was the U.S. government, particularly the State Department and Defense Department, so adamantly against that kind of bombing? Well, for FDR, he wanted more than anything else to bring the war to a close. And he didn't want anything to jeopardize that. But we have this paradox. FDR, the man who uplifted the hearts of Americans with his fireside chats, the man who got us through the Great Depression, that he was considered one of the great humanitarians who was walking on the face of the globe. And yet here, when confronted with probably history's greatest humanitarian crisis, he flinched. It's very interesting. When Winston Churchill first heard about Auschwitz, he said, oh, my God, this is the greatest crime against humanity in all of human history. And then he said, let's bomb Auschwitz, use my name, get everything you can out of it. With FDR, surprisingly, he started learning about what was going on as early as 1942. And by 1944, there was a very daring, really bold and brazen escape from Auschwitz itself where two Jews, they hid in a wood pile, they eluded the SS, they eluded the Nazis, the Gestapo, and they managed to escape out of Auschwitz itself. And then after three days, they turned around and they saw these fires going up into the sky. The ovens still working overtime.  They ran for 17 days. They got away from the Gestapo that was after them. They got away from anti-Semites. They almost got into a gunfight. 17 days later, they get into Slovakia and they recount their story to the Jewish elders there. All of this would make its way back to Washington and then onto FDR's desk itself. Now, FDR, the Treasury Secretary, Henry Morgenthau was so outraged by what was taking place and even though he owed everything to FDR, he wrote a report to FDR saying this report is about the genocide of the Jews and the government's complicity in this. Imagine that. This being sent to of all people, FDR himself, and FDR was stunned. He was sick of the time, not feeling well. He said, what do you want me to do?  But as it turned out, as you asked, FDR's government was not on board for this. In the State Department, there was a man named Breckenridge Glong who was head of the visa section and every visa he got, it meant life or death for the Jew who was sending it. The Jews were cramming the consulates all across Europe and what Breckenridge Glong did was because the opposite meant sure death. He wrote a memo to all his different consulates and he said by various administrative means we can postpone and postpone the granting of visas to the Jews. So in the end, he could have saved two Super Bowls worth of Jews, 200,000 right then and there. It's very sad. But the one thing I want to say in defense of FDR and then being told by his people that it may hold the war effort back. Now, the War Department was against doing anything as well and John McCloy kind of led the effort against the bombing. Why did he think militarily it wasn't a good idea? Yeah, John McCloy was sort of the military version of Breckenridge Glong in the State Department and he came up with reason after reason as to why we shouldn't bomb the camps. He said we didn't have enough planes for the fight and it would detract. He said we couldn't fly that far to get over Auschwitz. But as it happened, we had been flying planes over Auschwitz for months as part of the oil war to degrade the Nazi war machine. So in FDR in 1944, what was the state of his health? The state of his health and this is really quite remarkable. Remember at this point it's FDR's fourth term in office. Not his first, not his second, not his third, his fourth term. He had chills that wouldn't stop. He would routinely fall on the ground in his oval office. He could barely scroll his name. When asked how he felt, he would often say, and he wasn't much of a complainer, he would say I feel rotten. I feel like hell. And then he had congestive heart failure. After the conference with Stalin and Yalta, he came back to the United States.  And they said if you don't get some rest, you will be dead within a year. And those words would prove to be prophetic. So he picked in 1944 as his vice presidential running mate, Harry Truman. Did he ever know Truman? Did he ever meet him before? His relation, he really had no relations with Truman. It was like a chess game where they were moving pieces on a board and Truman became the vice president du jour as it were. Well, not really understanding. In those days, the vice president did not have an office down in the White House. No, and they didn't have the power. You know, when Truman became president, his aide said to Mr. President we need to tell you something about this terrible weapon. And that terrible weapon, which he knew nothing about as one of the most important members of Congress, was the Atom Bomb. Before he was that ill in 1944, how did FDR show people that he could sort of walk with the idea of never showing him in a wheelchair? You know, it is something that's unthinkable in today's world. But there was sort of a gentleman's agreement between the press and between FDR that they would never show photos of him in his wheelchair or looking crippled. And, you know, they often took stock photos and they're very famous of him sitting with Churchill and Stalin and they're all in chairs. And so he looks perfectly normal. And, you know, they could have blown the whistle on it, but the press really loved Roosevelt. When he did walk, how did he maneuver himself so it appeared to some people that he was walking? Well, with more dexterity than we would. So, okay, Taylor, in 1972, you were the co-manager of the George McGovern campaign in Texas. Yes. Who was your other manager? Bill Clinton. And did you think at that time he might ever be President of the United States? Well, we lost Texas by 30 points, so I didn't think either of us had a future in politics. Okay. So after that time, you went on your career. He went on his career. And then when he became President of the United States, he called you and said, why don't you help me with my diary? And can you explain what he said and what you actually did 79 times? It was a remarkable story. It's a quick story. All I got was, the president elect would like you to meet him at Kay Graham's house. So Christy and I came down, had no idea. We said, why? They said, we don't know, he just wants you there. He comes through the whole establishment of Washington is there, the Joint Chiefs, everybody. And all of a sudden we see this buzz making its way through and he and Hillary made their way through the whole crowd at Kay. So Christy and I, we were talking to the president of the United States, he said, can you believe this? I hadn't seen him in 20 years and then he said, I read partying the waters, I read all the footnotes and a lot of them came out of presidential libraries. I'd like it if you would interview the people coming into my cabinet about what kind of records they're going to keep and tell me whether you think when we're dead 50 years from now a historian could do what you're trying to do the wall collapsed and I was swept over and I realized that in 30 seconds he had said I'm still the same guy but I'm thinking about things before I even take office about the material resources for American history and out of that grew I did interview all the people coming in not all of them but some of them and I went back I said it's a disaster, they're not going to take notes and if they are they're going to steal them and take them home and Rick said it was a way of going to jail that he heard that from Averill Harriman you don't take any notes and so forth so I said and you're not going to record your phone conversations which are bar none the greatest primary resource for presidential historians ever and they're already extinct so out of this grew the idea of having an oral history and he said he was going to train somebody in his staff and then the next conversation he said my staff will leak it quicker than anybody will you come down late at night and you'll record this oral history now you're living in Baltimore 79 times you came down here late at night go into the residence and you record him and then what happened to the tapes I had two little recorders because I was paranoid that some would happen to one of them and when we were done I would rewind the tapes and gave them to him but it was a practical problem presidents don't do anything they don't carry money they don't have a wallet what was he going to do with the tapes he was paranoid that they were going to leak and if word leaked it would be subpoenaed because he said I want to put on here things that I can't say now but I want people to know when I'm dead so eventually we found a place in his sock drawer and we would put both of the tapes and then I would drive home to Baltimore and dictate everything I could remember about what all we covered and what it was like so you took the dictation of your notes and then you wrote a book about it was he okay with your writing a book he was okay with my writing a book until it came out oh then what happened he didn't like the book but mostly because of Hillary I will say it was because of Hillary because it came out in 2009 when Hillary was in the State Department and she was thinking of running oh she had just it came out in 2008 and she was running against Obama and he said you've got all this personal stuff in there about Hillary and I said well I'm writing a memoir of what it was like and he says you have it in there that Hillary came in with cold cream on her face and said she'd had a dream about Henry Kissinger and would I help her interpret it and I said well yeah that happened that doesn't sound presidential you know anyway so it went around it was too personal for him and then he was very upset and then typical Clinton maybe a year or two later he called up and didn't even say hello he does this sometimes he said Taylor you were right and I was wrong people don't care about those things about Hillary they actually kind of like them so you still have a good relationship with them I have a decent relationship I don't see him very much but I don't have any money to give the Clinton foundation so Bill you've written your 30th book is The Dreams of El Dorado and that's about the winning of the West so-called winning of the West I don't use the term winning of the West but yeah history of the American West settlement of the American West so as we expanded this country the most important expansion I assume was the Louisiana Purchase would you agree with that Louisiana Purchase is actually where I start the story so it's the history of the American West the geographically begins at the Mississippi River and extends the Pacific Ocean chronologically it begins with America's first purchase of territory west of the Mississippi which is the Louisiana Purchase and I carry the story to the beginning of the 20th century by which time the West as it existed in the 19th century was largely fading into memory by the 20th century the West looks a lot like the rest of the country so it no longer has this distinctive identity and it no longer has this distinctive place in American consciousness so the Louisiana Purchase how did that actually happen when Jefferson was a person who didn't believe in a strong government mostly what power in the Constitution gave the U.S. government the right to buy all that territory Jefferson was like many strict constructionists who had something of a conversion experience upon entering office and he decided well okay power is this distrustful thing when wielded by other folks but with me it's okay what Jefferson wanted to do was something he had been thinking about from the time he was governor of Virginia in 1779-1780 he had been trying to figure out who was going to control the Mississippi River this was in the middle of the American Revolutionary War and it was by no means clear the United States was going to win the war and secondly if it did win the war he wrote to the Spanish governor of Louisiana Spain controlled Louisiana at that time and started to talk about trade between the Ohio River and the Mississippi River and New Orleans because at that time this was before steam boat and everything went downstream and so all of the produce that farmers in those valleys made would find their way to New Orleans and so when he became president he felt it was really important for the United States to acquire at least to land goods on the dock in New Orleans better still to buy New Orleans from well initially he thought it was Spain but Napoleon's strong armed Louisiana backed from Spain so then with France and his envoys were off negotiating a deal when Napoleon decided Napoleon had reacquired Louisiana in order to restart France's New World Empire but it didn't work out because of an uprising or a revolution in Haiti and he sent an army over and 90% of his soldiers died of yellow fever within six months and so he decided okay that's not going to work out so I don't need Louisiana so he offered to Jefferson via the diplomats in Paris would you like to buy the whole thing and Jefferson at this point realized that there's nothing in the constitution that says that either the president will acquire new territory and as a strict constructionist Jefferson believed that if it's not written down in the constitution that you can do it then you can't up the federalists who took rather looser constructionist view who were quite thrilled with the idea of exercising power they had a good laugh at Jefferson's expense because here is Jefferson trying to figure out how he's going to work this through one answer to this but that was going to take too long and Napoleon might change his mind so Jefferson basically swallowed his scruples and cut the deal and the federalists they chortled a bit more but they realized it was the best deal that would ever arrive on the lap of the United States so he swallowed his scruples that's never happened in Washington since then so how did he persuade Lewis and Clark to go across the country what was the incentive for them to do it and what did they really discover that was so significant so the official title of the Lewis and Clark expedition was the core of discovery and it was a scientific expedition in fact this was probably the first example of federal funding of scientific research so what they were going to do is basically find out what it was that Jefferson and Congress had just bought because knowledge of the Louisiana territory was really sketchy they didn't say that no one neither American nor probably any Indian had ever traveled from the Mississippi River clear to the Pacific Ocean in a single shot now the first part of it was perfectly authorized because this was territory just acquired by the United States so Lewis and Clark were fine to the crest of the Rocky Mountains beyond that they were kind of on their own because they were in a legal no man's land the Oregon country was up in the air it was claimed by the United States it was still claimed by Spain and so Jefferson said once you get off there just watch out what you do and how long did it take to do the expedition so it took two and a half years and in fact once they left they left from St. Louis they went up the Missouri River they spent a winter in North Dakota near what's now Bismarck and then they took another year to get to the Pacific once they left Fort Mandon near modern Bismarck they essentially fell off the face of the earth as far as anybody knew and so for people like Jefferson he thought they might all be dead and when they reappeared after two and a half years in St. Louis this was fantastic it was like they had come back to life so what happened after they came back what was the fate of those two individuals William Clark had a long career in the military for a while and he became a governor of Missouri Territory as late as I think it was the 1820's or 1830's Mary Weather Lewis also remained in the West and he died under mysterious circumstances and it's unclear whether he was murdered more likely he committed suicide Jay you wrote a book that became a New York Times bestseller called April 1865 so what happened in that month anything important what was the most important thing that happened that month well the two most America was saved right I guess the most the most important thing that really happened in April 1865 is that this was when the war came to a close and it came to a close in rather dramatic fashion it there was a real possibility that guerrilla war could have been waged against the Union and US Grant carrying out the wishes for Abraham Lincoln met with Robert E. Lee and this was an extraordinary scene that set the tone for the peace that they were hoping to forge that would be a lasting peace Lincoln had said to Grant and Sherman earlier just about a month and a half earlier he said you know when this war is over there must be no bloody work there must be no hangings there must be none of that in other words he was saying there should be a soft peace a tender peace so that north and south can become brothers again so when Robert E. Lee went to go surrender to US Grant and you know Lee was tired and exhausted his army was surrounded and he had said just before and now he must go meet General Grant and I'd rather die a thousand deaths than do that Grant did several quite important things he allowed the defeated rebels to keep both their side arms and their horses now think about this if you're worried about guerrilla warfare being carried out this makes no sense whatsoever we honor you we may have defeated you but we are to become brothers again and then when the surrender documents were signed then Lee went on and mounted his horse and thousands of men were were out watching this dramatic piece of history playing out and Grant came out and he looked over at Lee and he tipped his hat to salute him as an honored and valiant foe and that would set a tone for the peace to come but the other thing about April 1865 obviously is what happened just five days later the assassination of Abraham Lincoln talking about the assassination so Lincoln gave a speech at the White House who was listening to that speech that got excited about that speech and upset about it a very well known actor, John Wilkes Booth and what particularly upset him about that speech well this is being streamed I'm just trying to figure out how to put this I mean I well I would say you can describe it without saying it it means black citizenship and he was just furious about it and it drove him almost to a state of madness so prior to that John Wilkes Booth had previously had a plan to kidnap Lincoln and what happened to that plan well it just proved logistically to be too difficult to carry out so after he heard Lincoln say that maybe freed blacks would be able to vote someday in effect that's how he interpreted it and it was not the kidnap Lincoln but to assassinate him and who else this is what's so remarkable and so dramatic and most people don't know this but it was served there 9-11 of the day so think of this April 14th five days after the surrender of Lee but Lee had only surrendered his army there were still three confederate armies in the field Jefferson Davis was calling on for continued war and even Mary Lee a descendant by marriage of George Washington and Martha Washington, she was calling for continued fighting and so what happened the same time at night at 10-15 three assassins fanned out John Wilkes Booth puts a bullet in Lincoln's head he's dead the next morning at 7-20 across the street from Ford's Theater the second deadly assassin made his way to the Secretary of State Seward's house and he stabbed him not once, not twice but five times and Seward's life was hanging by a thread and then the third deadly assassin was going to make his way to Andrew Johnson's hotel room at the Kirkwood House the last second did he get cold feet he was drunk and didn't do it he was drunk and he just got cold feet but picture the amount of chaos in that evening the New York Times editorialized it was a night of horrors and it was people literally feared being murdered in their beds and then one final point is that they actually thought there was a coup underway and they thought Bill Sherman, their great general was behind that coup that day Lincoln had a headache and wasn't sure he wanted to go through with his plan to visit Ford's Theater, I think to see our American cousin was that and so he was thinking of cancelling as I understand it but he said people have been told I'm going to go they're going to come because I'm there so I'm going to go, is that right? so who was going to accompany him who did he actually want to accompany him he actually asked a number of people including US Grant but Grant's wife didn't think much of Mrs. Lincoln I can't fathom that I just I thought she had seen her recently yell at somebody or something like that okay so Grant said we have Mrs. Grant Julia Grant said let's get out of town so we don't have to go so had Grant gone would he have had more military around him and maybe Lincoln would have been better protected or not, it's not the case it's highly possible that had Grant gone not only would a booth have killed the president but also our general okay so Taylor you wrote a very well known article in the Atlantic that later became an e-book about college sports and how pure they are, I think that's right so is it your view that college athletes should be compensated if they're superstar basketball or football players or that we should keep the idea that they're going to be amateurs I started out thinking like most people that there was a way my old college president Bill Friday at UNC not Duke but UNC told me Taylor please take the university and give it back to Socrates and get all these networks out of here because they've commercialized it and that was basically my thought but the more I worked on it I had a conversion experience I decided that our problem is that we can't see the difference between what goes on in the classroom and in commercialized sports and that the real question is rights I don't think anybody ought to be paid but I don't think anybody ought to be stripped of their right to ask for pay and I think that's what's happened by collusion that the colleges have said if you're in this school and you play a sport you can't even get a hamburger or a phone call and you can't get a ride home or anything of value we don't treat any, we don't hyphenate any other students they're 14 million out of the 20 million college undergraduates who have jobs outside the classroom but the athletes are the only ones whose rights we cancel and abrogate and say that you can't negotiate for anything and to me it is collusive theft and that the universities are involved in theft so it took me a long time to get there it wasn't easy because we are all there's something in the halls of ivy about college athletes and that there's something really pure about it but the same thing happened 40 years ago with the Olympics which were even more strictly amateur than college sports now they were horrified by the idea of a scholarship but we were losing so many medals to the Russians in the Cold War that Congress stepped in and passed the amateur reform act of 1978 that said all the U.S. Olympic committees had to have a percentage of active athletes on their governing boards and immediately all the amateur rules dissolved and nothing bad happened to the Olympics so anyway the world is cracking public opinion is shifted but the college sports establishment and the networks will hang on to this gravy train for as long as they can worse than a snapping turtle and it will be hard to get rid of it and the basketball story Duke I should have been compensated right absolutely okay Bill you wrote a book about MacArthur and Truman and that relationship why did Truman fire MacArthur and was MacArthur surprised that he was fired it's hard to tell if MacArthur was surprised he was a little bit shocked but he probably saw it coming Truman fired MacArthur because MacArthur's approach preferred approach to dealing with China in the Korean War differed from that of Harry Truman and the administration and MacArthur kept giving speeches that contradicted the policy that Truman was trying to lay out in particular what MacArthur wanted to do was to widen the war in Asia he believed that World War III had already begun the United States was fighting a major communist power namely China and therefore the only thing to do was to go all in Truman on the other hand believed that World War III had not begun and it was his prime responsibility to prevent World War III from happening Truman believed that the Central Theater the Cold War was Europe and if the United States got deeply involved in an Asian war it would render itself and its allies vulnerable in Europe which is why he wanted to calm things down MacArthur took just the opposite view he wanted to escalate things Truman did not fire MacArthur for insubordination because MacArthur did not violate any direct order primarily because the joint chiefs of staff were so intimidated by MacArthur that they refused to give him any direct orders because as one of their staffers said well if you want him to do this why don't you just order him to do it he said because he probably won't do it and then what will we do MacArthur was far more popular than Harry Truman in the minds of most Americans he outranked Harry Truman and so Truman had to deal very gently with this Truman was asked later so why did you fire MacArthur and he said I didn't fire him because he was a dumb son of a bitch although he was but if that was the case I'd have to fire half the generals in the army no I fired him because he refused to accept the direction from the president of the United States and the constitutional issue was really important Truman did take it personally he thought it was a much bigger deal to ensure that the military leadership in the United States especially in the early days of nuclear potential in warfare this was a time when the Soviet Union had just acquired nuclear weapons that it was more crucial than ever that the generals not think that they can make policies themselves MacArthur was fired he came back and made a famous speech but did it drive him up the wall that his aid to camp Eisenhower became president and MacArthur never got very close to becoming president MacArthur was one who started to believe his press releases and his press releases were put out by a group of sycophants that he had gathered around him and so he really thought this thing going he was indeed very talented and he had brilliant moments of leadership the counter offensive at Incheon which circumvented the North Korean lines and really changed the age of the war with something that everybody said couldn't be done and he said that's exactly why it will succeed but he got letters from home saying that you should be president of the United States rather than this scoundrel Harry Truman and he started to believe he could be and he came home this is why there's some reason to believe that Truman essentially wanted to be fired so that he could come home and challenge that MacArthur wanted to be fired so he could come home and challenge Truman directly he came home and was given an opportunity to address a joint session of congress and now you can watch the speech on YouTube and it's a fantastic speech but what MacArthur didn't realize was that the cheers that he received then were really for what he had done in the past not what he might do in the future he had never come home for his victory parade after World War II and so when people started thinking about well what are you going to do for me next when he ran for president the idea of being a general a general in the White House seemed okay but MacArthur was actually quite aloof and when another general had the common touch there Dwight Eisenhower came along through his general's cap in the ring he quickly put MacArthur in the shade and MacArthur didn't mind that of course so speaking of Eisenhower in June of 1944 there was the D-Day invasion did Eisenhower why was Eisenhower put in charge of that he really had very little combat experience how did he get to be in charge of the D-Day invasion you know FDR was at the Tehran conference with Stalin and Churchill and everybody assumed it was going to be Marshall so it was Marshall this, Marshall that he was the army chief of staff then the army chief of staff and then the more FDR thought about it the more he thought he wanted Marshall by his side he needed him so he asked Eisenhower he asked Marshall to make the supreme basically sacrifice he said it's going to be someone else someone else is going to be Eisenhower and Eisenhower proved to be a brilliant pick okay now Eisenhower planned the D-Day invasion with lots of help from lots of other people but he also thought it might not work and he prepared for that he had a statement was he really worried that it would not work you know in wartime as Carl Klauschwitz once taught us anything can happen you know we had it was almost unthinkable that we could lose but one never knows so there's a story that Hitler was asleep and that they had eight Panzer divisions ready to thwart the invasion but nobody wanted to wake him up so they waited eight hours or so and had that made a difference had he gotten the Panzer divisions quicker well it could have made a difference these Panzer divisions were significant weapons of war and would have greatly changed the military calculus but the Fuhrer and his bunker he was up the night before with a dull rambling monologue surrounded by his yes men and his lackeys and his doctor who was giving him 28 pills a day and then even General Rommel the famed Desert Fox he was off buying shoes for his wife for her birthday Now Taylor when you're writing a book how many pages or words can you do a day before you're exhausted I don't measure it that way I measure how long do I sit in the chair okay how long can you sit in the chair and at the end of 12 hours you say I'm done and sometimes it could be one page or 25 pages no I've never done 25 pages I would not try to convince anybody of that I don't write as many I'm trying a more difficult book now so I probably I'll write two pages a day and when you go back the next day and look at what you wrote do you always say that was brilliant or say this was terrible I always say it could be improved and typically when you're writing five days a week or seven days a week six days you've written 30 books so you must have no writer's block right no in fact I can't imagine what writer's block would be for a writer of nonfiction because we don't have to make stuff up if you don't know immediately what to write next we'll just go look at what happened and write that I have friends I have a lot of friends who write fiction and I can understand writer's block there because you have to figure out what to write next in the case of the fictional writers they have almost sort of too much freedom there's too much you could write about this you could write about that but when you write something that really happened I just if I can't think of what to write at the moment I go do some more research and then I figure out what comes next How much do you write a day while you're also teaching I never keep track of how much I write and it's because even until now and I've been doing this now I enjoy the process of writing and so I enjoy putting the words down on the page I enjoy shaping them up I sometimes think of writing as being like carpentry where you got these pile of wood and these are my facts and then you try to fashion them into something that makes either artistic sense or used sense or something like that and so because I enjoy doing it I don't pay attention to how long I'm doing it or how many pages or words I've written it does help me that I have a relatively short attention span I know lots of I know lots of writers in fact I know lots of would be writers who think that they have to have a block of four hours or six hours or a week or a weekend or a summer a sabbatical or something like that before they can really rev up I did my first writing when I had young children around the house and young children need to be tended to and so long before my children learned what ten minutes what a duration of ten minutes was they got used to the idea of well just wait till I finish this paragraph and then I'll get you whatever you need so if I have fifteen minutes I'll write for fifteen minutes and then you write long hander in a computer not a computer so as soon as a computer write long hander a computer first book legal pad second book Smith Corona and ever since then so Jay how much do you write a day when you're writing six to eight hours a day I like to do and then I follow a routine where the next day I kind of look at what I did the day before and what was your question does it look brilliant or just terrible and the answer is it depends sometimes things come out really well for me the shaping of the narrative the use of the words the flow of the story that's as important to me as anything I say so usually in that second day when I start looking over what I did the day before I crafted I recraft it and I find that usually when I'm halfway into a book I finally understand what I'm writing about and I finally know what I want to say so what and you write long hander a computer and upon a computer computer so what are you most proud as my kids will tell you I'm not very good with a computer so Taylor what are you most proud of having written I assume your trilogy or what would you say you're most proud of having written I'm sure my trilogy my most inspirational moment around writing was taking a course from Hannah Arendt in the late sixties but I wasn't writing that she was just mind boggling just to be around what would you say you're most proud of having written I've written in various genres of history I wrote a series of biographies and biographies are relatively easily straightforward to write and the narrative arc is basically the life of this of your subject so in terms of what I'm proudest of as a writer it's the ensemble pieces where you have a bunch of different folks sort of like April 1865 where what are how are you going to get all these people to fit together so I wrote a book on the California Gold Rush which brought people from all over the world to California and I had to select the individuals had to select them partly because they wrote down or they otherwise saved their experiences so I have to find the voices and I have to be able to create these characters that can come to life on the page but in this case they all had to arrive in the same place at roughly the same time and so part of it was good luck that they did part was my insight in choosing the ones that I did and there were times when I simply had to fudge and I tell my students this that if you discover that chronology is getting awry that if you you get to this point in history then you have to backtrack just try eliminating the dates just don't say what year or month has happened just say it happened because your readers don't particularly care and unless it's crucial to the cause the line of the story the causation that something happened before something else just don't tell them and they won't get distracted when you give a test to students and they don't have the right date it doesn't make a difference right so I tell my students when they ask about dates and some of them do I say the only reason the dates matter at all in history is to keep the order of events straight so if A happened before B then possibly A caused or influenced B but if B happened after A B could not have caused A so in your case what would you say? I would say for one thing I love all my children so in a sense I love all my books but my book April 1865 was on the bestseller list for a long time, number one bestseller and it's got fans who range from President Bush to Bill Clinton to John Roberts to Tom Hanks and Dave Petraeus so it's a book where everything just came together and all of my other books are measured against it I close the end of our time and I'm sorry that I didn't have time to let everybody speak but because the authors are going to be here you'll have a chance if you want individually to ask them as they're autographing their books I'll tell you what one anecdote I'll close with one of the writers that I interviewed for the book that I did is David McCullough and he's a very famous writer of course many of you have read his books it's a very unique way of writing basically he writes I guess it's a couple paragraphs at a time and then he gives them to his wife Rosalie his wife of 65 years I think it is and she reads it back to him so he can hear how it will sound if somebody's reading it loud and he wants to make sure it sounds right so they've been doing this for all of his books and one time he wrote out a paragraph and gave it to Rosalie and Rosalie read it back to him he said okay sounds alright she said no there's one sentence in here I don't think it works he said read it again now it's okay she said no it really isn't god damn it it's okay and they went ahead with it okay so the book comes out it wins a Pulitzer Prize and somebody wrote a review I think it was Gore Vidal in their book everything is perfect in there except there's one sentence in there but I can't believe David McCullough wrote that sentence anyway okay so David thank you very much for hosting us and Jim thank you very much for hosting us as well I think there's going to be a signing back outside so thank you all for coming I hope you had a good, enjoyable time thank you very much thanks thanks thanks


I welcome you all for the series of lecture on metrology, so now we will start the lecture series on module 10 in which we will be discussing about the comparators, topics covered in this module are interaction to comparators, the various features of comparators and how the comparators are classified, various types of comparators will be discussed as also advanced comparators will be discussed. Now we will start the first lecture in this module number 10, topics covered in this first lecture are interaction to comparators and the various features of the comparators and how they are classified, we will learn about the classification of comparators and also the users of comparators. Let us start the introduction to comparators. Now these comparators indicate the differences in size between the standard and the workpiece being measured, there is an integral display unit with sufficient magnification, that means it does not indicate or it does not measure the actual dimension of the workpiece, but it indicates how much it differs in size from the basic desired dimension. However, the comparators can be used for direct measurement within its range of operation, for example the range of the direct indicator is 0 to 10 millimeter, within this range the comparator can be used for direct measurement of the workpiece. Now this picture shows the basic system of the mechanical indicator, so we have a stage where in the standard and the workpieces can be placed and there is an arrangement, there is a column to which the comparator can be mounted and the differences, initially we have to place the standard on the table and we should set the reading of the comparator to 0 and then we have to remove the standard and we have to place the workpiece of unknown size between the table and the spindle and the dial indicator of the mechanical comparator shows the reading which will be difference from the basic size. These comparators are the instruments calibrated by means of end standards, for example slip gauges to quantify unknown dimensions. The purpose of a comparator is to detect and display the small differences between the unknown dimensions and the standard. The difference in the dimensions is detected as displacement of the sensing probe, for example the contact probe in the dial indicator, the movement of the contact probe in the dial indicator and the difference in dimension is also detected by comparison of shadow with a chart gauge which we will be discussing after some time. The important and essential function of the instrument is to magnify the small input displacement so that it is displayed on an analog or distal scale. Comparators are used in mass production to inspect the components to very close tolerances with high degree of position and speed. Quickly we can inspect the workpieces and we can segregate as acceptable workpieces and not acceptable workpieces. Use of line standards such as linear caliper and micrometers require considerable skill in the use of these instruments whereas use of comparator is relatively easy and quick. Multiple dimensions can be checked in a very short time using comparators. Let us study the basic features of comparators. Any comparator consists of a sensing device which faithfully senses the input signal and there is a magnifying system to amplify the signal input signal to suitable level. For this magnification different methods are used like mechanical methods, optical method, pneumatic method, hydraulic method or electronic method of magnification and any comparator will essentially consist of a display system commonly a scale and a pointer is used. Now what are the desirable features of comparators? Now the scale of the comparator should be linear within its operating range. There should be wide range of wide range for comparison so that it can be used for within a wide range of application. There should not be any backlash and friction between the moving part should be very very less and inertia of the parts various parts should be less. It should be very precise and it should contain should have good measurement accuracy and the indicator should be very much clear so that we can easily take the reading. The indicator can be analyzed as shown here so I can see the analog indicator. So it starts from 0, 0, 1, 2, 3, 4, 5 again in the counterclockwise 1, 2, 3, 4, 5. This is the contact probe and we have the pointer and you can see the markings on the scale are very much clear so that we can easily read and this shows a digital indicator so that we can easily take the reading. As also we can transfer the data via some communication systems to the computer system. Now the other desirable features are it should be easy to operate it should not require much skill of operation and no zero error the there should not be any pointer oscillations oscillations it should move smoothly over its range and the system should be robust in design so that it withstands the reasonable yield usage and the measuring pressure should be very low and it should be uniform throughout the operation and there should be inbuilt compensation for temperature effects. So you can see here a system which has a comparator system with the base and there is a column you can see the threaded column so that this measuring head can be moved up and down this height between the table and the probe can be adjusted depending upon the workpiece size and also these tables are replaceable depending upon the application. We can change the tables and this is the sensing probe and the output this is an example for electronic comparator and LVDT the when we place the workpiece between the table and the probe the probe will move and the signal is sent to the indicator and the pointer will move on the scale corotary scale we can select the desired range and sensitivity of operation. Now how these comparators are classified depending upon their design they are classified as mechanical comparators electrical and electronic comparators pneumatic comparators optical comparators which uses optical system fluid displacement comparators multi-check comparators in which multiple dimensions can be checked at a time and then automatic gauging machines. Now let us start the discussion on mechanical comparators now let us study the different displacement amplification systems what are the different types of amplification systems used in the mechanical comparators and what are the various types of mechanical comparators different types are available like dial indicator read type mechanical indicator sigma comparator Johansson micro theater and internal group comparators. Now the displacement amplification systems used in the mechanical comparators are illustrated here different amplification systems are used in the mechanical comparators like rack and pignon and gear train you can see this is the spindle contact spindle which contacts the workpiece so when the workpiece is placed between the table and the spindle the spindle will move in so spindle is connected to the rack and rack we have the rack on this rack cut on the spindle and we have a pignon here when the spindle moves that is rack moves pignon will rotate. So this rotation of the pignon is amplified using the gear trains finally the motion is transmitted to the pointer and pointer will move on a rotary scale and then we can take the reading now this is a very simple gear train with 10 is to 1 ratio and we have another simple gear train with rack you can see the rack which contains the contact probe so when the rack moves up and down this gear train will rotate and we get an amplification of 10 is to 1 ratio and then we have compound gear train with rack so this is the rack and then we have a compound gear train which will give us 100 is to 1 magnification ratio and then we have length of indicator indicator hand F so this is the length of indicator as the length of indicator increases there also we get some amplification now another amplification mechanism used is lever mechanism so this is a simple lever with 10 is to 1 ratio you can see here this is the contact point and this is the pivot the distance between the contact point and pivot is 1 millimeter here one unit and distance between pivot and the in tip of pointer is 10 so that the signal displacement signal is amplified by 10 times now this shows a compound lever wherein we get an amplification of 256 times so this is the contact point and this is the pivot and this is here we have another secondary lever so totally we get an amplification of 256 times so another mechanism is cam and gear train this is the measuring the splinter with the cam and then we have a set of gears so using this we get the amplification of the signal and this is another system with which uses lever with gear using lever system we get some amplification and using the gear train we get added amplifier further amplification of the signal but these are other systems to amplify the input signal this is the lever and gear so this is the lever and gear and the twisted strip and this is the lever combined with the band bound around the drum we have a drum here and a band is bound around this drum so there also we get amplification of the signal now let us study a very common type of mechanical indicator that is dial indicator so this dial indicator measures change in length and it does not measure the length itself however within this range of operation it measures the actual length of the workpieces for example if the range of the dial indicator is 0 to 10 millimeter the range is 0 to 10 millimeter and if the workpiece size is say 5 millimeter so the mechanical dial indicator can be used directly to measure the length of the workpieces so various names are used for dial indicators depending upon the type and purpose including dial gauge probe indicator test indicator dial test indicator drop indicator plunger indicator etc now this picture shows the arrangement of the dial indicator this is the table on which the standard or workpieces are placed so this is the reference point and this is the standard for example slip gauge can be used as standard to set the desired distance between the plunger and the reference point now they say we want a desired height of 10 millimeter this is the basic dimension then we use a slip gauge of 10 millimeter dimension we keep it between the plunger and the table that is the reference point and we set the dial indicator to read 0 we adjust the height of the dial indicator so that it is 0 now we remove this standard and we place the workpiece whose height is to be checked that is placed workpiece is placed between plunger and the reference point if the size of the workpiece is greater than the standard size that is 10 millimeter then this is the error or difference from the basic size so this difference in size can be measured using this dial indicator arrangement now let us study the basic operation of the mechanical indicator dial indicator this is the dial indicator and we have a granite table or cast iron table this which is the reference point and then we have a column on which we have we have an arrangement for mounting the dial indicator the dial indicator height can be adjusted by moving this bracket or it can be dial indicator itself can be more up and down and then it can be clamped using this knob now this is the height this height can be adjusted depending upon the workpiece height now initially we have to adjust the height of the indicator to accommodate the workpieces of different heights and then we have to insert this gauge between the spindle and the reference point between the contact probe and the reference point that is surface on top surface of the reference table and we should set the indicator to read zero now we should remove this gauge and insert the workpiece standard should be removed at workpiece whose heights are to be inspected they should they are inserted between the table and the plunger and then if the size is different from the standard size the pointer will move and that will show the change in the difference difference so that is recorded now let us study the construction of the dial indicator there are many parts in the dial indicator this is the indicating hand and then we have a rotary scale with markings and there's a dust cap to protect the rack and we have a bezel to protect the pointer and the scale bezel clamp and then we have this stem connected to the body of the dial indicator and then there is a rack or spindle and then the contact probe is connected mounted on the rack now there is a mounting lug using this this can be mounted to the stand now this shows a dial indicator wherein you can see we have a pointer and then we have a revolution counter and this is the scale you can see this is zero and this is 10 so this zero to 10 we have 10 markings each small marking represents 0.01 millimeter so when the pointer moves from 0 to 10 so the displacement of the plunger will be 0.01 into 10 that is 0.1 millimeter so like that if the pointer completes one revolution so it will be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1mm so if pointer completes one revolution the movement of the plunger will be 1 millimeter like that you can see the pointer can rotate 10 10 strand revolutions so we have 10 markings here 0, 1, 2, 6, 7, 8, 9, 10 so the range of this dial indicator is 0 to 10 millimeter and least count is 0.01 millimeter now let us see the internal construction of the dial indicator this is a mechanical type dial indicator you can see the contact plunger stem and the back cover is open this is the spindle varying the rack so rack is cut and rack is connected is contact with the pinion and then we have a set of gear trying and there is a spring to bring back the spindle back to initial position when we remove the workpiece so this is a digital dial indicator you can see the display display and then we can set the tolerance limits upper limit and lower limit we can also set we can select the display range for example 0 to 10 millimeter, 0 to 20 millimeter, 0 to 30 millimeter so the range can be selected now the magnified view of the internal structure you can see the spindle on which rack is cut and the pinion is in contact with the rack and there is a spring to bring back the rack when the workpiece is removed and this is the guide for the rack and the spring and there is a gear train for amplification of the signal gear train amplification is the most common method used to magnify the dial indicator motion that is the plunger motion because its accuracy meets the requirements of comparison measurement in use the sensitive contact probe is part of a rack in which a series of three to five years magnifies and transmits the movement of the contact probe to the pinion gear on which the indicator hand is mounted now we can see the dial indicator back cover is opened I am pressing the plunger we can see the movement of the plunger we have a guide for the movement of the plunger and the guide rod we can also see the rack and pinion we can also see a spring now different types of dials are used this is a dial with continuous clockwise markings 0 to 90 markings and this is a continuous counter clockwise markings and this is the balanced type that is in the clockwise we have 0 to 50 markings and then in the counter clockwise we have 0 to 50 markings and then we have flat and round contact points so we have this is the flat contact point and this is the anvil of the table on which workpiece is mounted a workpiece with a flat surface a round workpiece okay now it is very essential that the surface of the flat contact point should be parallel to the anvil surface otherwise the it will give error and we can see here round contact points now when we use round contact points and when we are checking the round parts it is essential that the contact point contacts the maximum size of the workpiece for example the diameter of the workpiece if we place the cylindrical object like this then we get the error in reading so readability of the dial indicator is another important thing I can see here commercial dial indicator where in markings are there and they are very much clear so reading is very easy also one can have a digital indicator so wherein you can select the system at a system or in this system now the measurement errors in dial indicator I can see here in this picture we have the table on which the workpieces are placed now we have this dial indicator mounted on this arm now when we insert the workpiece what happens if this arm is not rigid enough it will bend and then we get a wrong reading so how do we eliminate this deflection of this support we should use a very rigid very strong arm or else we have to minimize the overhang of this dial indicator it should be moved as close to the column as possible also we can minimize the deflection of these supports using the extra support cash one here now what are the uses of dial indicator so it is used in the turning work to check whether the whether we have achieved the proper size of the workpiece it can be used to check the wobbling of the rotating surfaces it can also be used to check the roundness of the work parts you can see the workpiece is mounted on the block and then the rotation is given to the workpiece so it is rotated and then readings of the dial indicator are taken if this is not round then this will indicate what is the amount of error also it is used to check the wobbling in the rotary source the amount of magnification of an indicator depends on its use and desired resolution dial indicators can have gear trains that amplify the movement anywhere from 40 is to 1 to 1500 is to 1 that means a magnification of 1500 times is possible this can give a dial indicator a discrimination or resolution of 0.02 millimeter 2.001 millimeter the total travel or reading capacity of the dial indicator commonly ranges from 0.075 millimeter to 50 millimeter or more so in the case of long range indicators for example 0 to 100 millimeters 0 to 105 150 millimeters the gear train drives revolution counters you can see here we have this pointer the main scale and then a revolution counter you can see here which tells how many revolution the pointer has rotated the revolution counters that tell the user the number of times the hand has traveled around the dial and thus the range of indicators displacement can be known these dial indicators are calibrated using slip gauges or using dial gauge calibrators so you can see here a calibrated span which is used to calibrate the dial indicators dial indicator which is to be calibrated is mounted and you can see there is a disc with markings and then we have to note down what is the reading given by this standard calibrator and what is the reading given by the dial indicator and then we can we'll come to know what is the amount of error in the dial indicator so this is another calibrator which is a distant time now let us study how we can use a dial indicator as a comparator we can see we have a slip gauge box the slip gauges are used as a reference to set the basic size the dial indicator now we have the round the workpiece and a linear caliper to measure the diameter of the workpiece with close view of the workpiece now we can observe the dial indicator fixed to the scan now we can we are observing the replaceable table these replaceable tables can be changed depending upon the workpiece we can see the slot in the stand to accommodate the table the dial indicator is fixed in the bracket the least count of the dial indicator is 0.01 millimeter and range is 0 to 10 millimeter now we can adjust the height of the dial indicator to accommodate workpieces of different heights by rotating this nut we can adjust the height of the bracket we can raise it or lower it in the column now I am measuring the diameter of the workpiece using the linear caliper the diameter of the workpiece is 19 millimeter now I have to select 19 millimeter slip gauge I am setting two slip gauges one nine millimeter thick and the other one 10 millimeter thick after cleaning the surfaces of slip gauges we have to ring them properly to build a pile of the desired thickness now we can see a slip gauge pile of 19 millimeter thickness after ringing we can use this pile to set the basic size the dial indicator we have to insert the slip gauge pile between the table surface and the dial indicator so this is the desired size 19 millimeter is the desired size so we have to set the dial indicator to read 0 by rotating the bezel now the dial indicator is reading 0 that means when the gap between the spindle and the table surface is equal to 19 millimeter indicator shows 0 millimeter now we have to remove the slip gauge pile now the reading is zero we have to remove the slip gauge pile and then we have to insert the workpiece which is to be inspected so I am inserting the cylinder which is to be inspected and we have to rotate it slowly so that we get the maximum reading so and we have to slowly rotate or roll the workpiece I can see the pointer is moving so we have to note down the maximum reading so the maximum reading is three divisions that means the least count is 0.01 millimeter so it is giving five divisions so the workpiece size workpiece diameter is greater than the desired size by five divisions that means 0.05 millimeter that means the size of the cylinder is 19.05 millimeter now we have another type of dial indicator known as dial test indicator we can see the photographic view of dial test indicator we have a lever which moves in this fashion so the lever moves in this fashion the pointer will move actually it will indicate the movement of this stylus so whenever we want to measure the displacement for example we have a workpiece like this placed on the surface plate now depending upon the height of the workpiece stylus will move up and down so the movement of this stylus is amplified by using this lever so we have a pivot ball bearing we have a pivot here and then we have a lever at the end of the lever we have a gear sector and which is in engagement with this is the gear sector this is in engagement with a pinion so pinion will also rotate so the rotation of the pinion will be transferred to the pointer to the pointer by means of the gear arrangement and the pointer will move on the scale and we can note on the reading so we can amplify the displacement of this stylus by means of this lever arrangement now we will move to another type of mechanical comparator known as read type mechanical comparator this sketch shows the arrangement of read type mechanical comparator we have a member two members so member a this is the movable member which will move up and down and there is a fixed member these two are connected by means of horizontal reads we have a horizontal read here and we have another horizontal read here so these two are the horizontal reads named R1 now we have a set of vertical reads R2 so one vertical read is connected to the movable member and another vertical read is fixed to the fixed member now when the component is inserted between the surface plate and the plunger the plunger will move so this x is the input displacement depending upon the height of the component plunger will move up and down and then movable member A will also move up and down the two vertical reads they are joined at the top and then a pointer is fixed at this point so since the two vertical reads are joined when the plunger moves up and down the read will tilt in this fashion and hence the pointer will also move and then we can note down the reading displacement reading a linear motion of the spindle moves the free block vertically causing the vertical read on the floating block to slide past the vertical read on the fixed block now as these vertical reads are joined at the upper end the two reads are joined at the upper end instead of slipping the movement causes both reads swing through an arc and the pointer swings through a much wider distance the amount of pointer swing is proportional to the distance the floating block has moved but of course very much magnified now this shows the amplified view of the fixed block and then the vertical reads this is the spindle which is fixed to the movable member and two vertical reads are joined together at the end of at the top end we have the pointer so now a is the displacement depending upon the height of the workpiece the a can be positive or negative and then when the height of the workpiece is greater than the standard of the desired height this spindle will move in this direction and the pointer will swing in this direction if the height is smaller than the desired height then this wing will be in this direction and pointer will swing like this and then we can go down the reading there these comparators are available in magnifications ranging from 500 to 1000 comparators of this type have sensitivities of the order of 0.002 millimeter per scale division now again we have read type comparator wherein the mechanical pointer is replaced with an optical lever so this is the top end of the reader reads vertical reads and we have a lamp and a lens so we get a light beam here so light beam will go will move in this direction we have a mirror so light is reflected back so when the top end of the read moves swings in this fashion the reflected light will also move on the scale and hence we can note down the displacement of the spindle so in this case magnification is of time by the length of this vertical read as also the magnification is further magnification is obtained by this optical arrangement now we are coming to the end of the lecture 1 in module 10 in this lecture we learnt about the basics of dial indicators what are the basic features or characteristics of the mechanical comparators what are the purposes of comparators what are the uses of comparators what are the various types of comparators and then we also learned about the construction and working of mechanical type dial indicator now we will stop here and we will continue the discussion on other types of comparators in the next lecture thank you