The Cavalcade of America presented by DuPont, maker of better things for better living through chemistry. To those Americans who have labored in the service of a great free press. And to those men and women of today who are ever alert, so that through our press the people shall know the truth. The Cavalcade of America proudly dedicates this story of one of American journalism's historic crusades. The Cavalcade of America presents an original radio play, Mightier Than the Sword. Written by Robert Talman and based on the life of the great American cartoonist, Thomas Nast. During the 70s and 80s, Thomas Nast fought to secure decent civic government by means of his celebrated drawings and the power of an American free press. Starring in the role of Thomas Nast is William Johnstone of the Cavalcade Players. Our Cavalcade Orchestra and the original musical score are under the direction of Don Voorys. DuPont, maker of better things for better living through chemistry, presents William Johnstone in Mightier Than the Sword on the Cavalcade of America. It's a summer evening in the year 1869. Two men are strolling down a quiet suburban street on the outskirts of New York City. One is Fletcher Harper, publisher of Harper's Weekly. The other is Thomas Nast. Presently, they arrive at the door of an old-fashioned two-story house.  I should be charmed. That's a fine way to greet the boys, Elizabeth. Well, I'm sorry, it's Kate. That's our maid, Mr. Harper. Well, let me take your thing. Thank you. You will stay to dinner, won't you? Well, Elizabeth, you invited Mr. Harper, didn't you? Well, what's wrong? Oh, Tom, Kate is in such a state today. Come on into the parlor. Just make yourself comfortable. And excuse me, I'll just tell Kate we're ready when dinner is. Elizabeth, what is all this? Well, it's something about Kate's brother, Tim. He's a fireman in New York. It seems he's in some kind of trouble. Anyway, they've got him in jail and they won't let us see him. I think you'd better talk to her, Tom. Yes. Elizabeth asked her to come here. Maybe we can get to the bottom of it. All right, but don't you keep it too long. There's a roast in the oven. Kate! Yes, ma'am? Mr. Nass wants to talk with you for a moment. Oh, ma'am, I'd rather not... Not this way. Come down and sit. You look perfectly all right. Don't you worry about a thing. Kate, you remember Mr. Harper? I do that, ma'am. Well, it seems to be the trouble with your brother, Kate. It's... Well, you see, sir, Tim's a member of the Tenth Ward Fire Brigade. Never broke a law in his life, sir. And now they've got him in that blood-loss street jail. Oh, it's that dirty of the arms to Harper. Tenth Ward. That's Boss Tweed's old brigade, Tom. What's the charge against your brother, Kate? I don't know. He don't even know, Mr. Harper. They just come around and told him he's talking too much. But they couldn't put him in jail for that now, could they? Well, we'll see to it that they don't keep him there for that. So don't you worry, Kate. Thank you, sir.   I'll be after it. Go right along, Kate, and don't worry.  This time in your own kitchen. Not only in my kitchen, Mr. Harper, but in the house next door, in every house in New York, the grocery on the corner, the cup and the beat, the police courts, the school board, every business, every public institution, even our charities, corrupted and plundered by Boss Tweed and the rotten political scoundrelism in City Hall. Tom, we've talked about this time and time again. And more and more I'm convinced the only way to stop Tweed is through the press. The only trouble there, Mr. Harper, is Tweed's victims can't read most of them. True. Print isn't enough. What about your cartoons, Tom? One picture is worth 10,000 words. You're right, Mr. Harper. And those ringleaders make perfect subjects for pictures. Peter P. Sweeney, the sniveling, shifty bank clerk. And Slippery Dick Connolly. Why, he's been a sneak thief ever since he was kicked out of grammar school. And his honor, the mayor. Okay Hall, a cheap gambler, only with a whole city treasury for stakes. And then William Marcy Tweed, the boss. Mr. Harper, I see him as a kind of false staff, a fat clown leading a sinister army of his hoodlums. Good. Mr. Harper, they've been at it for years. When is our magazine going to print the truth about them?  But now go ahead, draw whatever you like, and I'll start printing them in our next issue. Now that you're here, I want to have a little talk with you. Mayor Hall, instead of adding 65% on all the city's bills, jack them up another 20%. I can arrange that, Bill. Sweeney. Yes, boss? We're going into the publishing business. We're timing that ride called a transcript. You might get the official newspaper of New York, and say that it carries all the municipal advertising. Now it's on your mind, Conway. Uh, nothing important, boss. That fireman, Tim Murphy, is out on a hapus corpus. But if he starts blabbering... We are supposed to be a lawyer, Sweeney. What can we get him with now? Trump up any charge. Try stealing.  The warrant can say, Stephen, can it? You heard him, Conway. Slap that one on, Murphy. And be sure this time, he's taken before the right judge. Now, here's the main thing that's on my mind. I want action on it before elections. What is it, boss? A little street improvement project. I think we ought to straighten out Broadway. Why, straighten out? Would you think the public will stand for that? I know the public. If I didn't, you fellas wouldn't be in City Hall. Now, don't get sore, boss. You know the boys would rig up an awning over Central Park if you gave the word. I know. Bill, I don't think you have to worry. Every ward is safe, sure, or well-being. Loads are getting too expensive. Now, listen and get the point. If the city improves Broadway, we have to buy up the buildings that are in the way, won't we? We mean going to real estate. It's not a bad idea, but that'll take a lot of money. There's not much left in the city treasury now. Well, you've got a board of estimate for us. Sure. They'll appropriate the rest. And I want you boys to see to it that the property owners and the contractors subscribe to our benevolent association fund after the project gets underway. And get the idea over that this thing can't be done for pennies. There ought to be 25 million in it for us. Don't you think we're going a little too far, Bill? I thought I made myself clear. Hi. I think you want to know something. You seen a copy of Harper's Weekly lately? No. What about it? Well, I just bought a copy on the way over here.  Here. Who drew that cartoon? There's his name. Thomas Nast.  Diamond pen and all. Tweedledee and sweedledum. So I steal from the public treasure and hand out to the poor. Harper's Weekly, huh? I'll show them publishers they can't make a fool of me. Convict. Yes, boss? This Harper. He sells school books to the board of education, don't he? He does. All right. And I have that fellow McAllister come over and see me tonight. I've got something to tell him. Sure, boss. All right, boys. I guess that's all. Go ahead with the Sweet Project first thing in the morning. All right. Good day, boys. Oh, Connelly. One thing. Yeah? Four slips of my mind. Don't forget to send a hundred weight of coal to Mrs. O'Reilly this afternoon. Okay. Wait a minute. Tell the alderman to spend $1,500 and every ward for coal for our voters. Nay, and the villains march wide between the legs as if they had fetters on. For indeed, I had most of them out of prison. Is that caption of quotation from Shakespeare, Mr. Nast? With variations, Harry. With variations. What do you think of the cartoon? Think Tweed makes a good fall staff? Very good, Mr. Nast. Thanks. Well, send this under the printers. Right away. Oh, Mr. Harper asked me to have you come in when you have. I'm going in right now. Oh, come right in, Nast. You know Mr. McAllister? Glad to meet you, sir. Mr. McAllister? I'm a friend of Mr. Tweed, Mr. Nast. Oh, by the way, Mr. Tweed asked me to compliment you on the good likeness you're drawing of him in this current series of cartoons. I'm flattered, sir. Yes. But no, Mr. Nast, the fact is Mr. Tweed is worried. Sure we say unnecessarily worried, perhaps. I believe it is like, well, doing anything that might embarrass Mr. Harper. Do you mean that as a threat? Gentlemen, do you think it's good practice to worry in your readers with politics? All the people who want is to be left alone. I've heard Mr. Tweed say many times over they're much happier, much better off when you don't upset them. Well, you know, Mr. McAllister, you'd better tell Mr. Tweed you heard me say they deserve to know the truth. I see. Mr. Harper, for some time the Board of Education has been dissatisfied with your school books. As an advisor to the Board, I've tried to minimize their complaints because I've had your interest at heart. I should very much regret being put in a position to sacrifice them now. I believe I understand, Mr. McAllister. And I want to thank you for giving us a good idea Tom, what about a series of cartoons exposing the Tweed influence on the Board of Education? I'll get to them right away. You know, Mr. Harper, whatever happens, you'll have to answer to your stockholders, won't you? Good day, Mr. McAllister. Hey, boss, look at this. All right, what is it? What is it? The cover of Harper's Weekly. You and Sweeney and Mayor Hall. Come on, look here. Nass calls him OK Hall, spelled H-A-U-L.  I wonder if he thinks this is funny. And see what it says underneath? Wholesale and retail. Is you and the boys coming out of the city treasury and a cop is bowing to you? That's Wholesale. In the other, a tramp has... Look, a tramp has stolen a loaf of bread and the cops have beaten him. That's retail. Wholesale and retail. I'll take care of this later. But, boss... Then come inside. The boys are waiting. Hello, boss. Sit down. How many of you numbskulls have seen this cartoon? Why, I did. Well, boys, looks like this fellow Nass knows too much for his own good. Ah, don't let it worry you, boss. What's the difference? I don't care what they print about me. Most of our voters can't read anyway. Give them one look at a picture like that and they'll begin to get ideas. Maybe we can talk to Nass alone. Ah, that's what I've been thinking. Boys, there's a fellow who can do that for us. You know who I mean. Go down to the street and put pressure on him to go and see Nass and get results. I... I don't think Nass can be bought, boss. Me neither. Boys, you surprised me. I thought you knew Nass and a wife and children. Well, Mrs. Nass, Yes, what is it? What do you want? I should like to see your husband, please. Ah, what is it you want to see Mr. Nass about, please? Why, perhaps you'd better take my card, madam. Well, I... I suppose you can come in. Thank you. I see you've heard of my firm anyway. Why, Mrs. Nass, do you're trembling? I'll call my husband. I'll just take a seat here if you don't mind. Thomas, there's someone here to see you. I was just coming in there, my dear. Here's his card. Oh. Well, to what may I attribute this signal on us, sir? Mr. Nass, this business is as unpleasant for me as it is for you. I think perhaps we'll understand each other better if I tell you I have a wife too and three children. Oh, Thomas. I'm sorry, sir. But if your business has to do with... Perhaps you'd better hear what Mr. Gillespie has to say, Thomas. Thank you, madam. Mr. Nass, I saw the gentleman with the ill-concealed black jacks and pistols standing outside your house. I can well imagine what you and your wife are going through. Well, what is Tweed's ultimatum? I believe I've made no reference to Mr. Tweed. As a matter of fact, I know a party who is interested in your work. They realize, of course, your time is valuable, but I have reason to believe they'd advance you $100,000 to finance a trip abroad. $100,000? Do you think they'd offer $200,000? Possibly. I shouldn't be at all surprised. Oh, I see. Don't you think I could get $500,000? Yes, Mr. Nass. You can get $500,000. I'm waiting for your answer, Mr. Nass. No. Absolutely and finally no. Thomas. I made up my mind a long time ago to help put Tweed behind bars, and this is the first time I realize how near I am to doing it. Well, Mr. Nass, you have courage, but be careful you don't put yourself in a coffin. Good day, Mrs. Nass. Good day. Good day, sir. Good day. Thomas. Are you afraid, my dear? I'm afraid for you, Thomas, afraid for all of us. Let's go away, Tom. Now, somewhere where it's safe. Somewhere safe? My dear, if Tweed and his kind are allowed to go on without opposition, there soon won't be a safe place for free men anywhere in America. Our answer to Tweed is cartoons and more cartoons and ridicule until the fight is won. And Elizabeth, I don't think we'll have long to wait. Oh, Tom. Yes, Mr. Harper. Come here quickly, will you? Yes. And what is it, sir? Tom, look here. Look at these proofs. It's the Tweed story they're publishing in the Times tomorrow, and they've got the real evidence at last. I want to see plastering Fire Commissioner's offices. $2,147,061. Two tables and 40 chairs Tweed's apartment. $360,061. Why? It's incredible. It may be incredible, but it's true. Fuel heating loft, 18 John Street, one month. $87,061. Where did they get these figures? Connery's own records. Sheriff O'Brien was the one who copied them out. Tweed offered to bribe the Times. $5,000. Not to publish them. But George Jones is going to print them every day. The Times? Now we don't have to fight alone, Mr. Harper. It's the beginning of the end for Boss Tweed. He'll have to stand trial now. And in a court he can't buy. Enter in the court. Case of the people versus William Marcy Tweed. Judge Davis presiding. The defendant has been found guilty of grand larceny on 204 counts. The defendant's former position in civic affairs is of no concern to this court. But in view of his health and present financial condition, the court imposes the minimum crime and a sentence of 12 years in a jail of the county of New York. Well, Tom, the king is dead. You mean the ring is dead, but Long lived the king. Tweed is as alive as he ever was. Every morning he lives Ludlow Street jail and goes driving in the park. Dines at home with a bailiff for his butler. I know, Tom. We've scotched the snake, but we haven't killed it. But how to go on from here? We'll go on, Mr. Harper. People don't realize the fight's just begun. Mr. Harper. Yes, what is it? This next one just came in. Tweed's escaped. What? Escaped. I see it. Tweed escapes, believed to have fled the country. Well, Tom, what have you to say about that? Mr. Harper, I'll tell you. I'm going to draw one more cartoon of Tweed, and I want you to print it on the cover.  A picture of him in prisoner's stripes. And the caption is going to be in big letters. Big letters so everyone can read them. And there'll be no excuse for missing the point. Want it? Or the crime? Ahoy there, Carmen. Ahoy. Spatial police for the Vigo Spain. Ahoy there, Carmen. Ahoy. Spatial police for the Vigo Spain. Lord the Ladder. Lord the Ladder. Stay there. Lopez. Ariaga. Yes. Come aboard with me. Make her fast. Look sharp for any boats that may come alongside. Also for anyone who might try to swim aboard it. Yes, sir. Well, Lieutenant, welcome to my ship. We will dispense with formalities, Captain. I have a special warrant from the government made on behalf of the American consul. You know the man in his picture, Captain? There is a certain resemblance. But, of course, that's quite impossible. This is an American magazine. Resemblance. To whom, Captain? There he is. Right over there, scrubbing the deck. Come. We talk to him. But, Lieutenant, you can't. He's a deaf mute. He can't talk at all. We see. Oh, there, fellow. Up on your feet. Up on your feet. You see? Yes. I do see. Send your tweed. Have you anything to say?  Well, send your tweed. I have nothing to say. Well, here it is, Mr. Nast. The story of tweed's capture just as it happened. Caught by your cartoon. That was a great job, all right. Thank you. I guess that's the end of Boss tweed. Thanks to you, Mr. Nast. Oh, not to me, Joe. Thank a free press. A public that can be aroused to against the things tweed stood for. No one man deserves the credit. You know, Mr. Nast, you certainly had tweed down to the last whisker. I understand when they caught him he had every drawing you ever made of him. You must have seen a lot of him drawing him so well they recognized him on a Spanish ship. When I drew the first cartoon of tweed, I'd seen him only once. Only once? Yes. I met him on the street one day. And nothing. We nodded and said good morning. Then we went our ways. Two men and the crossing of their paths marked the end of one epoch and the beginning of another. The downfall of William Marcy tweed gave rise to a great and potent force in American journalism. Mightier than the sword of any form of tyranny or degradation. And for his part in one of the most heroic crusades in the history of our free press, Thomas Nast takes his place in the cavalcade of America. The cavalcade of America thanks William Johnstone and the cavalcade players for their performance of mightier than the sword. And now the DuPont Company brings you its story from the wonder world of chemistry. There's a saying in the Midwest that sometimes you can hear the tall corn grow. If you put your ears to the ground and eyes to the future anywhere in America, you can sense the country growing, growing in productiveness, in strength, in self-awareness. Let's put our collective ear to the ground in a typical American city. Newburgh, New York. The home of the DuPont plant that makes fabricoid pyroxil and coated fabrics. The storybook kind of history touched Newburgh in 1782 when George Washington spent the winter there after the battle of Yorktown. Today it's a quiet city of red brick and gray stone sloping down to the historic Hudson River. On the edge of town is the DuPont plant with one old stone building still there that was standing in Washington's day. If we had been there in 1910 we would have seen the plant making chiefly a black coated cloth fabricoid for carriage upholstery. In 1917 we would have seen the beginnings of the first washable window shade material, tontine. A little later we would have seen the plant expand its facilities to take care of defense needs confronting the country in 1918. Water proof leggings for soldiers gas proof gloves upholstery materials for cars and trucks. But the past 20 years have seen the greatest growth. Today we stand in the plant on the edge of Newburgh and watch great roles of snowy white cotton cloth undergo a remarkable change. We see a stream of pyroxilin being impregnated into a continuous path of cloth flowing over and under giant rollers emerging as new materials of beauty and usefulness. In contrast with the black coated fabric for carriage upholstery in 1910 the DuPont plant at Newburgh today produces pyroxilin coated fabrics in endless varieties of color and grain for furniture upholstery train, bus and truck upholstery luggage, briefcases motion picture screens, adhesive tape, belts, handbags bindings. The list goes on and on. Another coated fabric, PX cloth goes into waterproof and vermin proof book bindings. Development of new products and uses means a corresponding growth in plant capacity manufacturing skill and research facilities which contribute to a strong national economy. An illustration of how this accumulated knowledge and skill form part of the national security is the recent cooperation of DuPont chemists with the Navy department experts in working out special formulas for airplane dope. And all the resources of Newburgh as of other DuPont plants will continue to be placed at the service of this country whenever needed. Such dedication to the nation's welfare is ever the purpose of the men and women of DuPont who bring you better things for better living through chemistry. And now Ted Joatt of the Cavalcade Players to tell you about next week's program. Ladies and gentlemen, next week the Cavalcade of America welcomes back to its microphones the distinguished actor of stage, screen and radio, Claude Reigns in a radio play of an exciting moment in the history of our nation. In all the world today few are the places where a man can say what he thinks. We can in America. You're hearing this radio program right now because in America we enjoy every principle of human freedom. These all important blessings have come down to us because in the early days of our republic there were men who fought for them. One of these men was Thomas Cooper whose story we will bring you next week with Claude Reigns as Thomas Cooper on the Cavalcade of America. Thank you. On the Cavalcade of America your announcer is Clayton Collier sending best wishes from Dupont. This is the National Broadcasting Company.


Matt says, when a user has left an organization and their mailbox has been converted to a shared mailbox and their license removed, can their account then be deleted? They're currently showing in the active users list, but obviously are no longer active. If you're referring to Active Directory, which should be about the only place that would still appear, yes. When you converted mailbox from a user mailbox to a shared mailbox, it's a shared mailbox. It's not their mailbox anymore. So yes. Yeah, so if you're looking at it from a user perspective and it says that it's a user mailbox, yes, it can be deleted. If you're looking in exchange as a whole, it will tell you a category of what type of mailbox it is. User, shared, et cetera, right? So if you have one account that says that's a shared mailbox, that's the one you do not delete, right? The one that says that's actually the user mailbox, that one's free and clear, because technically it shouldn't still exist because it is migrated to a shared mailbox. So the mailbox should be fine, but then once you can confirm that it is shared, go over to the user, if they've got other licenses, yes, you can then remove those licenses from that user. Absolutely. And then the shared mailbox will still be there. Indeed, it will. Because shared mailboxes do not need licenses, just need permissions. Indeed. So there are any scenarios where removing the user licenses and then that shared mailbox, like something malfunctions or disappears, is there any scenario where that could happen? Well, it is micro... That, whoa, whoa, whoa, whoa, whoa, be nice, come on. That was her outside voice, wasn't it? Just like teams is teams, things can happen in teams. Things can happen. Don't normally happen with exchange. Exchange is a pretty robust and mature product, but. Thank you. But also keep in mind, in any scenario, you should always have a backup or store recovery system. Absolutely. So in the transition, which is built in to take a mailbox from a mailbox and convert it to a shared mailbox, is a built-in process, right? You do that and you get a success. I've seen successes and everything looks like it's great. And then when you go to access, there's a problem, what not? Well, you can't go back to the mailbox because it was converted to a shared mailbox. The only thing that you have to go back to is the actual backup or store method that you have within your organization. If you do not have one, then you darn well better be looking into one because please do not depend on Microsoft for that because Microsoft will tell you there is limitations to their backup and restore functionality. That is a problem. Sorry, I'm just gonna make a commentary here. Is it funny how Microsoft for years telling customers because the third parties have been in this space for 20 years and that Microsoft salespeople would actively work against the ISV partners and say, you don't need to have the backup and we provide all of that. And so suddenly Microsoft makes an investment in one backup company and suddenly everybody is now coming to the light and Microsoft sellers are aware that, yes, Gartner, Forrester, every other analyst firm out there telling you, you need to have a backup recovery solution in place that you should not rely on the out-of-the-box. I don't know if I was being, I don't know, jaded by all this years. I don't know, right? But when Microsoft told me, he's like, oh, hey, we backed this stuff up, I'm like, no, right? I was like, I'm sure there's caveats to it, there's a process to it and all that stuff. And if I need to restore and I need it right now, I guarantee you, I'm not gonna be able to get it, right? So do you want, please don't tell Microsoft if they did this, but do you guys know how I vetted their system backup restore? I submitted a false ticket. Oops. I said, I need this site restored right now, this date, this time, et cetera, right? And do you guys want to know, like the feedback that I got when I was doing this was, I need a business case as to why, is it in their recycle bin? Is it here? Have you done this? Have you done that? And they made me fill out an entire thing of my business case, why I needed this restore. And then once that piece got approved, then they said, okay, we're initiating that to another team. So then it goes to another team's queue. And then you wait in that queue for your restore. You were not notified when they do that restore. They do it and that restore has to be in the same exact place that it was. You can't say put it in this new location, it has to go on top of that exact site. So which means at the time that you submit, you submit your restore request, you have to, and hopefully someone let you know ASAP, which if you think about the recycle bin, you go, what, 60, 90 days or whatever that's held in there that they can restore from. If you know exactly when something was deleted and it's not in there, then you submit that ticket. That site needs to go to read only because any changes that were made after that fact or during that time are gonna be overwritten as soon as they do that restore. Wow. And cause just as much if not a bigger problem than what you're trying to fix. Yeah. Exactly. So not a viable solution unless it's a, hey, we don't care if we have to go back 60, 90 days to get the information, that's the only, that's the only thing that it will help you with. Other than that, you better have a third-party solution in place backing up your data every single day so that you can get that on point restorations that you need if something goes wrong, period. Yeah. Interesting. Well, one flag I wanna throw on the shared mailbox is, you have retention policies. Each company may purge their mail at certain points in time. So you wanna make sure that, even though you're not depending on historical information out of somebody's shared mailbox if they've left, if your company is actually purging them periodically based on their policies. So, well, it depends if they're purging or if they're actually doing an archive, right? Because they have in a mailbox, they have recoverable data. Right? So if they're, think about a legal hold, right? In a legal hold, they're turning it into a shared mailbox. You take anything that's active and whatnot and you put it in there, but then you also have to go to the recoverable mailbox area and restore all that to inside of that shared mailbox. So it's a multi-tiered situation in any type of those restores or migrations that you have to do, but someone has to give you the proper information. And Sherry, you know as well as I do cause I feel like that's coming from the same project. Right? If they don't provide us that information, we don't know that there's recoverable data because they've just told us to turn this user into a shared mailbox, right? They've not told us it was a legal hold user or any of that stuff. So we have to go get that recoverable data. So ask a lot of questions, get a lot of answers, then initiate that go button.


Today, we're going to look at one of the most important concepts in structural design, the concept of a load path, and how we can visualize it using internal force diagrams. To do this, let's start with a bit of a thought experiment. Are these beams equivalent? Intuitively, we may say that we expect these beams to behave quite differently, but what happens if we start to analyze them using the methods we have learned so far in this course? We have learned about making free body diagrams, so let's remove the supports and replace them with possible reaction forces. We also learned that we can calculate what these reaction forces are using equilibrium. If we evaluate equilibrium, we will find that the reactions are the same for both of these beams. As this is a simple load case, I'll leave it up to you to verify this result, but the result remains. The reactions are the same. Does this mean that the beams are the same? Well, not entirely. We would say that the loading on the beams is statically equivalent. They produce the same resultant force, which leads to them having the same reaction forces and moments. But we intuitively know that something must be different. We can validate our intuition by looking at how we test the wing of an aircraft. Here you can see the loading and unloading of an aircraft wing during testing. Where a very complicated load introduction system, known as a wiffle tree, is used to distribute the load over the entire wing. If a point load really would be equivalent, then we wouldn't go through all the trouble of using a wiffle tree. So what is the difference? The answer to this is related to the concept of a load path. So let's start by defining this. The function of a structure is to carry and transmit loads. Where you can view a structure as a connection between externally applied loads and supports or boundary conditions. The load path refers to how that load is transmitted through the structure. You can think of this as if the structure was a maze. The load will flow through the structure, depending on its design, until it reaches the boundary condition. We have actually already looked at this concept indirectly in our analysis of trust structures. Producing the internal forces in the trust members is the way in which we analyze the load path in trust structures. Take for example the following simple structure. We can analyze two separate load cases for the structure which cause it to behave as a trust structure as the loads are applied at the joints. We can easily see from the symmetry of the problem that both load cases are statically equivalent producing the same reaction forces at the removed supports in our free body diagrams. The calculation of those reaction forces is quite straight forward so I'll leave it up to you to verify. To analyze these load cases we would first identify the zero force members. If I fade away these members you are left with a partial view of the load path through the structure. Next we would calculate the internal forces in the remaining members using the method of joints or sections for which I will only show the final results. From this view we can clearly see that although the load cases are statically equivalent they have very different load paths. This can have a significant impact on the design of a structure in terms of deciding on the necessary strength of each of the trust elements for all the relevant load cases. But this is for a trust structure that is comprised solely out of two force members. How could we go about analyzing and visualizing the load path in more complicated structures such as beams and frames? Let's see how this would work for our uniformly loaded cantilever beam. We have already drawn the free body diagram and determined the reaction forces acting at the built-in support so we'll start from there. What we want to do is examine how the distributed load flows through the structure to the support reactions. To do this we need to cut into the beam to expose the internal forces and moments. We will do this at an arbitrary distance zed along the beam. Since we cut into the beam we need to think about the possible internal reaction forces that could be exposed at the cut surface. You can approach this the same way we did for determining the reaction forces at supports by examining the degrees of freedom of the beam that are constrained. As the two sides of the beam cannot translate or rotate relative to each other we need to add a normal force, shear force and bending moment in order to properly constrain our segment of the beam. As you will learn later on I am drawing my internal forces and moments in a particular direction but don't worry about that for the time being. With our new free body diagram complete we can now calculate these internal loads in the beam using equilibrium. Summing the forces in the zed direction we see that the internal normal force has to be equal to zero for the body to be in equilibrium. Summing the forces in the vertical or y direction we get the following expression. We need to remember that our distance zed is not a fixed value in this expression so if we rearrange it we can obtain an expression for the internal shear force within the beam as a function of zed. We need to be careful of the units in our expression so I'll make a little note here that the results will be in kilonewtons when zed is in meters. Finally we can sum the moments about the section plane taking the counterclockwise direction as our positive reference direction. By choosing this point to sum our moments the internal normal and shear forces will not contribute to the summation. Thus we end up with negative mx as it acts clockwise not counterclockwise being summed with the moment caused by the resultant force of the distributed load 2 times 10 minus z acting at a moment arm distance of 10 minus z divided by 2. If we rearrange this we can then obtain an expression for the internal bending moment as a function of z which will have the units of kilonewton meters when zed is in meters. We can take these three functions we have calculated and plot them as functions of zed as shown here. We call these diagrams the internal force diagrams and they help us visualize how the externally applied loads are transmitted through the structure in other words the load path through the structure. We can see the different demands placed on different parts of the structure which could influence the design and sizing of that part of the structure. We can visualize this better by looking at the difference between a point force and a uniform distributed force acting on a wing. Here we have the internal force diagrams for a uniform distributed load we just determined on the left as well as the internal force diagrams for statically equivalent point force on the right. By comparing the two sets of diagrams it becomes clear why we can't simply test a wing of an aircraft using a point force. In the point force case the free end of the beam is completely unloaded while the internal shear and bending moment carried by the clamped half of the beam differs from the distributed case except for precisely at the fixed boundary condition. The demands on the structure are quite different in these two load cases and would have consequences on how the structure would be designed and reinforced along its length. Hopefully this illustrates how important visualizing the internal loads within a structure can be in the design of engineering structures. You will see throughout your engineering career that a lot of time and effort is spent in understanding the load path through a structure and we will certainly be spending a lot of time in this course practicing how to do so.