52 Determination of 'the Acceleration of 'Gravity 'for Tokio, Japan. 



havo arisen from vibration of the point of support, we may 

 mention that we screwed the rigid brass plate on which the 

 steel knife-edge rested firmly to a principal beam of the roof 

 of the Physical-Demonstration room, which was built with 

 unexceptionally great rigidity on account of earthquakes, so 

 common in Japan. 



VI. Major Herschel ends his letter by saying that u the force 

 of gravity at Tokio, in Japan, is known more certainly from 

 the above formula than from the experiments recorded in the 

 paper under review." Now, even assuming that this were 

 true (a statement, however, with which we disagree entirely), 

 that is no reason why our experiments should not have been 

 published, since it is always important that results obtained 

 by one method should be confirmed by those obtained by 

 another. But he further says, the paper contains no means 

 of checking the result experimentally obtained. To remove 

 this misapprehension on his part, we sum up the numbers 

 involved in the calculations : — 



} 



934-99 



Length of steel wire, at 0° C., from 



knife-edge to circumference of ball 



Diameter of steel wire 0*045 



Weight of wire 11*6 



Diameter of brass ball ...... 8*20 



Weight of brass ball 2352-2 



Length of steel knife-edge about . . 

 Breadth of steel knife-edge about 

 Depth of steel knife-edge about . . 

 Weight of steel knife-edge about 

 Periodic time of pendulum for the ) 



above length J 



Amplitude, or complete swing back- \ 



wards and forwards J 



Value of g, pendulum being assumed Y 



a simple mathematical one (no > 980*06 



corrections) J 



Value of g, pendulum regarded as a 



compound one (uncorrected other 



wise) 



Correction for arc .... 

 Correction for buoyancy 

 Correction for air-resistance 

 Correction for air-inertia . 

 Final value of g experimentally ob 



tained for Tokio, Japan , . . 



centims. 



centim. 



grams. 



centims. 



grams. 

 4 centims. 



1 centim. 



0-5 

 7*8 grams. 



6-1496 seconds. 



30 



} 



} 



{ 



979-58 



0-00 

 + 0-16 



0-00 

 + 0-08 



979-82 



centims. 



cent, per 

 sec. per 

 sec. 





