556 



REPORT — 1894. 



for one of the tested conductors). Fourteen experiments were made, seven with 

 the test-wires interchanged relatively to the branches in which they were placed 

 for the first seven. The following table shows the means of the results thus 

 obtained, with details regarding the electrostatic capacities of the leyden-jars and 

 the voltages concerned in the results. 



In each case four leyden-jars, connected to make virtually one of capacity -02742 

 microfarad, were charged up to 9,000 volts, and discharged through divided channel. 

 The energy, therefore, in the leyden before discharge was 11-105 x 10' ergs. In 

 each of the first three cases 1,450 volts were found remaining in the jars after 



discharge 



in each of the last four 1,400. 



The mode of measuring the elongation of the test-wires was, as may be under- 

 stood from the preceding description, somewhat crude, but it is reassuring to see 

 that the mean results in the cases of 10-82 and 10-84 megalergs of energy used are 

 so nearly equal. The ratios for the two circuits are, in the two cases, respectively 

 1-48 and 1-4G. The conclusion that the heating effect in the test-vyire in series -with the 

 platinoid wire is nearly one-and-a-half time as great as that of the test-wire in series 

 with the iron is certainly interesting, not only in itself, but in relation to Professor 

 Oliver Lodge's exceedingly interesting and instructive experiments on alternative 

 paths for the discharge of leyden-jars, described in his book on ' Lightning Con- 

 ductors and Lightning Guards,' which were not decisive in showing any general 

 superiority of copper over iron of the same steady ohmic resistance, but even 

 showed in some cases a seeming superiority of the iron for efficiency in the dis- 

 charge of a leydeu-jar. Our result is quite such as might have been expected from 

 experiments made eight years ago by Lord Rajleigh and described in his paper 

 ' On the Self-induction and Resistance of Compound Conductors.' * 



3. On Fhoto-electric Leakage. By Professor Oliver J. Lodge, F.R.S. 



4. Report on the Present State of our Knowledge of Thermodynamics, 

 Part II., ' On the Laws of Distribution of Energy and their Limita- 

 tions.' By G. H. Bryan, M.A. — See Reports, p. 64. 



5. On the Possible Laws of Partition of Rotatory Energy in Non-colliding 

 Rigid Bodies. By G. H. Bryan, M.A. — See Reports, p. 98. 



6. On the Law of Molecular Distribution in the Atmosphere of a Rotating 

 Planet. By G. H. Bryan, i/..4.— See Reports, p. 100. 



FIiil. Mag., vol. xxii. 1886, p. 469. 



