Friday, August 30, 2013

Competing Telegraphs

It wasn't much after Samuel Morse invented the first electrical telegraph in 1837 that competing systems first began to appear. But the first recorded instance of the transmission of an electrical signal across wire was patented in London in 1750 by Benjamin Franklin. Yes, that Ben Franklin. He just detonated a blasting cap there was no message per se but the concept is similar. Another early experiment was in 1804 by Francisco Salva Campillo. He used multiple wires to represent letters in signals conveyed over a distance and the signal was received with each wires immersed in a separate glass tube of acid. The current would create bubbles which would indicate the letter. In 1809 German inventor Samuel Thomas von Sömmering re-worked the Campillo design so the signal could travel over a mile.

These do all sound ridiculous and impractical configurations, but the point is that the Morse system won out because it was the first practical system. he didn't invent it in a void.  That is evidenced by the fact that Prof. Charles Wheatstone, Charles T. Jackson  and David Alder all "invented" the telegraph around the same date.  Only a few years before the Morse system debuted, Carl Friedrich Gauss showed off a semi-practical electrical telegraph. He and and Wilhelm Weber built connected the Gottingen Observatory and the Institute of Physics; a distance of about half a mile.

Their prototype consisted of a coil which could be moved up and down over the ends of two magnetic bars. This motion generated an induction current that was transmitted through two wires to a galvanometer. They could also toggle the direction of the current. Using positive and negative states they encoded the alphabet in binary code. In 1832  Pavel Shilling revised an 8-wire model down to two. It was tested in Russia over a distance of 3 miles. The British government was interested in buying the design. Had Morse not had his own breakthroughs, either of these could have been a usable systems.
But what about afterwards?  The early success of the Morse system brought out as many imitators as innovators as money often does. Morse's patents were often licensed.. though sometimes not hence the lawsuits. Morse himself failed to credit Vail for the electromagnets in his model and that too was a point of legal contention. The first Morse-Vail telegraphers marked down code with pen and paper to be interpreted visually. It was only later that engineers realized they could just interpret the sound alone. As telegraph networks were built, some companies used a printing telegraph.

The first of these was developed by Mr. Royal E. House. His printers used paper tape not unlike early stock tickers. In 1846 a Scottish scientist, Alexander Bain, sped up the Morse system with a paper tape soaked in a mixture of ammonium nitrate and potassium ferrocyanide, which gave a blue mark when zapped with the current. But this was too fast so he re-engineered it as punched paper. His unit managed a top speed of 282 words in under a minute. This was more than 4x the speed of Morse's telegraph. Morse sued him of course claiming ownership of the paper tape idea. In 1848 Friedrich Clemens Gerke revised the original Morse code into a binary arrangement of dots and dashes. Sort of reminds me of VHS and Betamax.