410 



Messrs. Stables and Wilson on the 



In this second 



Fig. II. 



a 



^ 



tain modifications were therefore introduced, 

 form (fig. II.) a steel piano- 

 wire was used, the length of 

 which was 98*35 centim. and 

 the diameter 1-025 millim. 

 Suspended by this wire was 

 a stout brass rod, E, termi- 

 nating in a disk, F, upon which 

 rested a similar movable disk, 

 G ; and between the two disks 

 could befitted a brass plate, H, 

 carrying heavy brass rings, I. 

 To the bottom of the lower 

 disk an (unmagnetized) steel 

 bar K was attached, by means 

 of which the apparatus was set 

 in oscillation by the use of a r 



magnet. The apparatus used k~" 



in the water experiment was 



attached to the centre of this bar by a strip of metal attached 

 to D (fig. I.) and soldered to the bar. Great care was taken 

 to render the junction perfectly firm, so that no torsion could 

 possibly take place at this point. The moment of inertia was 

 determined as before, and found to be 186653 (C.G.S.). 



The first fact which was evident from the experiments was 

 that, although the apparatus when suspended in water oscil- 

 lated isochronously, it did not do so when suspended in the 

 saponine solution. The following table gives the results of a 

 number of experiments on the time of two long and two short 

 swings respectively in that solution: — 



Large amplitude. 

 10-90 sec. 

 10-70 „ 

 10-75 „ 

 10-52 „ 



With a thicker rod: — 



10-42 sec. 

 10-52 „ 

 10-33 „ 



Similar experiments in the case of water gave for two long 

 oscillations, 10*25; for two short, 10*30; for three long oscil- 

 lations, 15*5 and 15*75; and for three short, 15*6 and 15*75 

 seconds. 



The amplitudes denoted long and short are not all of equal 



Small amplitude 



10*28 



sec. 



10-28 



V 



10-35 



)•) 



10-35 



» 



9-85 



sec. 



9-73 



?j 



9-90 



?» 



