preceding. There was also a tenth plate, having a capacity equal to the whole of the largest set. The capacity of the ten plates was thus sixty-six times that of one of the smallest set. With these as standards of comparison, he measured the capacities of his other apparatus, and, when possible, modified his conductors so as to make them equal to one of his standards. His large Leyden battery he found to have a capacity of about 321,000 "inches of electricity," so that it was equivalent to a sphere more than five miles in diameter. One of his instruments employed in the measurement of capacities was a "trial plate," consisting of a sheet of metal, with a second sheet which could be made to slide upon it and to lie entirely on the top of the larger plate, or to rest with any portion of its area extending over the edge of the former. This was a conductor whose capacity could be varied at will within certain limits. Finding the capacity of two plates of tinfoil on glass much greater than his calculations led him to expect, Cavendish compared them with two equal plates having air between, and found their capacity very much to exceed that of the air condenser. The same was the case, though in a less degree, with condensers having shellac or bee's-wax for their dielectrics, and thus Cavendish not only discovered the property to which Faraday afterwards gave the name of "specific inductive capacity," but determined its measure in these dielectrics. He also discovered that the apparent capacity of a Leyden jar increases at first for some time after it has been charged--a phenomenon connected with the so-called residual charge of the Leyden jar. Another feature on which he laid some stress, and which was brought to his notice by the comparison of his coated panes, was the creeping of electricity over the surface of the glass beyond the edge of the tinfoil, which had the same effect on the capacity as an increase in the dimensions of the tinfoil. The electricity appeared to spread to a distance of 0.07 inch all round the tinfoil on glass plates whose thickness was 0.21 inch, and 0.09 inch in the case of plates 0.08 inch thick.