Cranks and eccentrics

Note: This was posted last month and I finally got around to making the correct battery for Morse’s original. I’m reposting at today’s date to add the battery, and ALSO because WordPress did some suspiciously weird ‘optimizing’ on one of the animations.  (It looked OK when first published.)  Looks like they’re trying to gradually erase the sender, in an oddly non-digital way. Probably not, but I never underestimate the Tech Lords.

Screencap from the ‘scrubbed’ animation.

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Last week I took a linguistic look at Morse and cranks and eccentrics. This led back into the old material on Morse himself and his first prototype. The prototype certainly had cranks, but the commenters were talking about Morse himself. In his memoirs and letters he comes across as a manic-depressive. Up and down, up and down, like the pistons of a steam engine.

I also realized that I’ve animated dozens of old telegraphs and pre-telegraphs, but I’ve never done Morse’s original. So here we go.

Morse didn’t invent the telegraph by any definition, but he did try to invent the linotype, and he tried to follow the Chappe system of phrasal coding.

His description of the first prototype:

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The Telegraph consists of four parts :

1. The Battery – Cruikshank’s galvanic trough of sixty pair of plates, seven by eight and a half inches each.

2. The Portrule – An instrument which regulates the motion of the rule. The rule answers to the stick of the printers, and in it the type representing the numbers to be transmitted are passed beneath the lever, which closes and breaks the circuit.

3. The Register – An instrument which receives and records the numbers sent by the portrule from any distant station.

4. A Dictionary – Containing a complete vocabulary of all the words in the English language, regularly numbered.

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Unquestionably the first bundling of hardware and software! The dictionary or lookup table was considered part of the device. Like the rest of the original package, it didn’t last. Much later, businesses and government agencies developed many sets of phrase codes known inside their own circles for their own purposes. These were ‘high-level compilers’, short words representing sentences or concepts, not numbers representing words.

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Overview of the system: Sender on left, operated by our Martian. Batteries in the middle, supervised by Happystar. Receiver on right, operated by Polistra.

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Here’s the sender all by itself, showing wires connected to the binding posts, with one of the type pieces (A) enlarged in front. The type pieces strongly resembled regular hot-lead type fonts, except that they were designed to lift the lever arm, not to make impressions on paper. Morse imagined a linotype-style device with a keyboard to select the pieces into the portrule, but this device was never developed.

The sender had a crank-driven belt, carrying the ‘portrule’ or typestick with the sequence of types pressed into its center slot. The belt setup strongly resembled the belt carrying sliders in magic lanterns.

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And here’s the sender in action: As the types passed under the stylus, they rocked the lever up and down, closing the circuit between the binding posts at each high spot.

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The Cruikshank battery is an early example of mass production in electrical equipment, starting in 1802. It contains 30 pairs of zinc and copper plates soldered together. The opposite sides of each pair face into cells of dilute sulfuric acid. Binding posts are connected to the outer zinc and outer copper plate at the ends. If we guess that each cell was producing about 1.5 volts, the total in series was about 45 volts.

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Morse’s original register or receiver was famously built around a leftover canvas stretcher. Like the sender, it had a slider-style crank and belt, in this case moving a strip of paper instead of the portrule. The crank served to pull up the weight on the right, which then drove the belt steadily through clockwork gears. (Mainsprings must have been hard to get; other prototypes like Sholes’s first typewriter also used weights instead of springs.)

The long triangle looks like it was meant to move left-right, but in fact it moved front-back. The magnet in the center of the stretcher pulled the triangle backwards when current was flowing. At the base of the triangle, a pencil was inserted loosely through holes, with a weight on top so it would stay in contact as the lead wore down.

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Finally, here’s the receiver in operation, repeating the contour of the types in the sender.

This trace would have been easy to read, and also formed a permanent record of the message for archiving. Morse’s number-based dictionary would have made immediate reading impractical anyway, so a permanent record was a necessary part of the original concept.

The register could run unattended for a while, then a transcriber would read the individual letters and consult the dictionary for the number codes.

All parts of this setup were modified or abandoned before the first commercial system. The portrule and types and dictionary were immediately replaced by the key sending verbatim letters. The paper register was refined into a more compact form, and continued through the teletype and early computer eras as punched paper tape.

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