Tuesday, April 10, 2007

More about the wires

Radio has two kinds of weirdos. Those lone weirdos that end up in a shack on the edge of town, and those other weirdos that choose to work in teams. How did George and Henry know each other? Henry Edward Highton was George E. Dering's Rugby coach... His autobiography here.

Highton and Dering were British inventors working on the problems of wireless telegraphy. Dering had no less than eleven patents one of which was for a very respectable Needle telegraph that was used by such respectable institutions as the Bank of England. More importantly in terms of modern radio were his three patents on three seperate methods of "carrying off atmospheric electricity" from the line wires.

These all regard the very earliest forays into grounding, sheilding, and insulation.

They are as follows:
1. "Two roughened or grooved metallic surfaces separated by fine linen, one of which is included in the line-wire circuit, and the other is in connection with the earth." (repatented by William Siemens as the Serrated-Plate Lightning-Guard)
2. "The attraction or repulsion occurring between dissimilarly or similarly electrified bodies respectively. Thus metal balls may be suspended from the line-wire by wires, which on separating under the influence of the lightning-discharge make contact with plates connected with the earth; or the separation may simply break connection between the line-wire and the instrument."
3. "Introducing a strip of metallic leaf into the circuit, this being fused by the passage of the atmospheric electricity." More here.

Dering won an award at the Great Exhibition of 1851 for his innovations. A few years later, at the Paris International Exhibition of 1855, he was awarded a medal for general excellence. It were these kind of endorsements that made the people with money listen to these two rugby players. Dering's proposed a transmarine telegraph. It was a pretty big idea that would require eithe rprogerss or luck in wire quality and the effectiveness of insulation.

"The metal composing the wires may be iron or copper or any other suitable kind, and it may be coated with varnish, by which means the amount of exposed surface will be diminished, and the metal preserved from corrosion. " He was betting on varnish. It was optimistic. He even began fantasizing about a wireless cable to America. "...take the case of a longer line, say from England to America, I should select two points, as the Land's End in Cornwall and the Giant's Causeway in Ireland or some suitable place on the west coast of Scotland, and corresponding points on the American shore." His tests were destroyed by bad welds in the bare wire. He managed to run about 12 miles of cable into the sea before ist snapped under it's own weight at a weak weld.

It was nto the first time this kind of idea went kablooey. Previously two other attempts were made to connect Great Britain to Ireland by cable. Both failures were by Newall & Co. In the years prior to that multiple terrestrial runs of cabel failed due to defective insulation. Point being that wires sucked, and insulation was terrible. This created the mood in which engineers wanted to do away with wire entirely... i.e. broadcasting.

In 1913 just after George Edward Dering's death Theodore N. Vail purchased his personal library from his estate. The eccentric inventor had kept virtually every publication he ever encountered on the subject of electricity. This collection numbered approximately 35,000 books, articles and pamphlets dating to 1508! Vail had the entire collection sent to the Massachusetts Institute of Technology along with a generous fund for cataloging and housing it. Forming the core of the Vail Library at M.I.T. it represented the most complete and historically significant collection of documents related to the development of electrical engineering in the World at the time.