To mitigate a steep ascent, a central carriage-way, 200 yds, long, is cut along the main street to a depth of 15 ft., the opposite terraces being connected by a bridge.
Subject to the rule as to the shortest distance to which the jack must be thrown (25 yds.), there is no prescribed size for the lawn; but 42 yds.
In Lombardy it has a breadth of 200 yds., and a depth of 10 to 16 ft., but the strength of the current renders its navigation very difficult, and lessens its value as a means of transit between Germany and Italy.
In 1885 Preece and Heaviside proved by experiments made at Newcastle that if two completely insulated circuits of square form, each side being 440 yds., were placed a quarter of a mile apart, telephonic speech was conveyed from one to the other by induction, and signals could be perceived even when they were separated by 1000 yds.
He discovered a fact subsequently rediscovered by others, that a tube of metallic filings, loosely packed, was sensitive to electric sparks made in its vicinity, its electrical resistance being reduced, and he was able to detect effects on such a tube connected to a battery and telephone at a distance of 500 yds.'