From a number of drop tests made at the Pittsburg Works, the following results were obtained : DROP TESTS (The fractions of inches stated in the table represent the permanent set of the test bar after the blow.) NUMBER OF BLOWS. a a a a a a a a a a a b a 11% 8 foot blows. Broke. g g a a a a a a d Broke. f Weight of drop 148 lbs. ; height of stroke 12 inches, except where otherwise stated; distance between the supports 4 inches; striking face of drop, a blunted wedgeshape; test-bars 6 inches long, 2 inches wide, and inch thick. The letters indicate the state of the surface of the test-bar on the side upon which the blow has been given: a, sound; b, slight cracks at edge; c, cracks at edge increase in size; d, slight cracks in middle of test-bar; e, cracks in middle increase in number; f, cracks in middle increase in size; g, remains unaltered; straight; test-bar reversed. At the Imperial Austrian Polytechnic Institution in Vienna experiments were executed by Professor R. Jenney with Phosphor-Bronze bars, showing the following results : In the Imperial Arsenal at Vienna experiments were made by Colonel Uchatius, giving the following results :— 9875 SILICON-BRONZE $ 74. In 1881 M. Weiller of Angoulême performed a series of experiments with phosphor-bronze wire, to test its suitability for telegraphic and telephonic conductors, and his results went to show that it possessed a conductivity one-third that of copper, but 2 times that of iron and steel. The conductivity not being sufficient for telegraphic purposes, he invented silicon-bronze, which is an alloy of copper and tin containing silicon. He thus obtained a wire presenting the same resistance to rupture as phosphor-bronze wire, but with a much higher degree of conductivity, rendering it applicable for telegraph purposes. Mr. W. H. Preece states that phosphorus has a most injurious influence on the electrical conductivity of bronze, and that silicon-bronze is far superior, and has entirely replaced phosphor-bronze for telegraphic purposes. It is also important to note that, although wires made from this alloy are very much lighter than ordinary wires, they are of equal strength; and it is affirmed that, if broken, they will not fall to the ground as the ordinary wires do; but by reason of their high elasticity they spring back and coil up close to the standards. The same is also true of phosphor-bronze. The following table shows the comparative properties of different wires :— |