Introduction to Analog Mechanical Computers

Courtesy of the United States Navy comes this incredible introduction to analog mechanical computers.

The context for this is that massive, mechanical computers were used aboard US Navy ships ranging from destroyers to battleships, from about 1944-1969, as part of the “Fire Control” system.  This type of computer would take up to 25 continuously changing input variables in order to calculate the proper bearing and elevation for heavy caliber guns aboard the ship.  This calculation— to ensure that a projectile will land at the place where the target is going to be —is marvelously complex, taking into account variables such as wind speed and direction, relative velocity of the ship and target, and parallax between the different guns on the ship.  What’s truly remarkable is that it was all done with mechanical  mechanisms such as gear differentials, cams, and mechanical integrators.

This two-part training film, from 1953, introduces the basic mechanisms that made these computers work:

The video embedded above (41:53 total length) contains both films, one after the other.  (And, the YouTube link is here.)

Basic Mechanisms in Fire Control Computers, Part 1 discusses shafts, gears, cams, and differentials. Note that the first couple of minutes are not so much about the mechanisms, but more of an explanation— to the servicemen —of why they needed to learn about them.

Basic Mechanisms in Fire Control Computers, Part 2 discusses component solvers, integrators, and multipliers


If you enjoy these training films, you may also want to read through the little book entitled Ordnance Pamphlet 1140: Basic Fire Control Mechanisms, available here in PDF format, which covers much of the same ground.



6 thoughts on “Introduction to Analog Mechanical Computers

  1. That’s an amazing piece of mechanical technology – but even more amazing is the fact that 50 years later those calculations could be done in an instant using off-the-shelf kit you can hold in one hand and schoolboy-level knowledge of maths and programming!

    Makes you wonder what computing will be like 50 years from now!

  2. Is it just me, or does the audio in the 1st video cut out shortly after the 6:00 mark?

    • Thanks! (And, I have no idea why that would have been removed like that.) I’ve updated the post with the video link that you’ve suggested.

    • Maybe, depending on what you mean by “computer.” Zuse made the first Turing-complete computer. If you go by that definition, the analog mechanical computers that are the subject of this article are *not* computers.

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