566 EEPOET— 1888. 



investigation may show that we have here a new kind of experimental evidence on 

 the relations of electricity and light. 



10. Gom'parison of Gassners Dry Cells luith LeclancJie's. 

 By Wm. Lant Carpenter. 



Two Ga.ssner's cells were examined, the round form having an E.M.F. of 

 1'317" and an internal resistance of 0"205'", the measurements of flat form being 

 1'52'' and OvOO". The E.M.F.'s were measured hj Law's condenser method, and 

 the internal resistance by Kempe's method, the shunt employed being 1". 



The resistance of a ringing bell, measured by the reproduced deflection method, 

 was found to be 20" . The two dr^' cells and a No. 2 size Leclanche were separately 

 circuited for 168 hours through 20" , and observations of the potential ditferences 

 were made at frequent intervals. Similar observations were made during the 

 recovery from the polarisation thus produced, and the results were plotted in 

 curves, which were exhibited. The round dry cell was circuited through 3" for 

 6j hours, the potential diflerences and internal resistances being measured at inter- 

 vals so that the current might be calculated. 



From the results obtained it appeared that the round form of dry cell polarised 

 less than a No. 2 Leclanche, but took longer to recover when the circuit was 

 opened, and its internal resistance was considerably lower, but that the flat form 

 polarised in most cases more than a No. 2 Leclanch6, and had the same internal 

 resistance. 



11. On the Intensity of Magnetisation of soft Iron Bars of various lengths 

 in a uniform Magnetic Field. By A. Tanakadate. 



Experiments were made on bars for which the ratio of length to diameter 

 varied from 13 to 32 ; the bars were subjected to different strengths of magnetising 

 fields, and the magnetic moments thereby acquired were measured, the mean 

 intensity of magnetisation being then calculated. The results agreed with those of 

 Professor Ewing on bars, for which the above ratio varied from 50 to 300. 



Mention is made also of some experiments by the author in 1883 wherein a 

 magnetic field of constant strength was used to act on a mass of iron that was 

 varied by steps. The mass consisted of iron wires, which M^ere varied in number. 

 With a field of 46 C.G.S. units the magnetometer deflection was sensibly propor- 

 tional to the number of wires up to 10 ; as the number of wires was increased 

 the ratio of deflection to number diminished, the maximum deflection practically 

 occurring with 25 wires, no greater deflection occurring with 41 wires. When 

 the wires numbered more than 10, some of them would be thrown out of the 

 bundle, requiring pressure to keep them in the solenoid, though the whole bundle 

 could with care be so placed that no wire would jump out. Each wire was obvi- 

 ously in an unstable state of equilibrium, being under the action of opposed forces, 

 one from the solenoid tending to throw it out, and the other from its fellow wires 

 tending to eject it. 



FRIDAY, SEPTEMBER 7. 



The following Papers were read : — 



1. Becent Progress in the Use of Concave Gratings for Spectrum Analysis. 

 By Professor H, A. Rowland. 



2. Is the Velocity of Light in an Electrolytic Liquid influenced hy an Electric 

 Current in the direction of propagation ? ^y Lord Rayleigh, LL.D., 

 Sec. E.S. — See Reports, p. 341. 



