This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 edition. ... while they are put into contact with the outer conductor, their bound charges will be determined principally by the induction of the outer conductor. The efiect of a hollow conductor upon the contact charges of two metals within it was shown by the present writer in an investigation published in 1912." A polished zinc ball S centimeters in diameter was insulated by a short piece of silk thread and suspended by a cord which passed over a pulley so that the ball could be lowered into a hollow conductor and charged by contact with its bottom and then raised and discharged to a gold-leaf electroscope of the C. T. R. Wilson pattern. Copper and aluminium beakers of about 750 cc. capacity were used as the hollow conductors. One of these beakers was placed below the zinc ball and earthed, and ten successive charges were taken from it by the zinc ball, which was raised and discharged into the gold leaf after each contact with the beaker. Then the other beaker was substituted, and a similar set of charges was taken from the inside of its bottom and shared with the gold leaf of the electrometer. The deflection of the gold leaf for each charge was read by a microscope and scale. As a mean of twenty sets of ten readings from each beaker, made in alternate sets of ten, the difference of the charges taken from the aluminium and copper beakers gave a difference of deflection in the gold leaf of 20.8 scale divisions, when the sensibility of the instrument was fourteen scale divisions for an ordinary dry cell. A disc of tinfoil a little larger than the bottom of the beaker was then pressed down into each beaker until it rested upon the bottom and was turned up about one centimeter around the inside of the beaker. The zinc ball was then charged as...