VALUE OF ACCELERATION OF GRAVITY— MENDENHALL. 



21 



In the present ease it will be safe to assume: 



and 



So that 



Sn_Tn_£n 

 *i _ Tx -«, 



= 1 



— — = ratio of thicknesses, 



111! 



_ 14.2 



l.vi 



A T„ = s . (1000136. 



For the determination of T the pendulums were allowed to vibrate uninterruptedly for from 

 six to nine hours, according to circumstances, a few coincidences being noted at the beginning 

 and end of this period, from which the coincidence interval and the period could be calculated in 

 the usual wa}'. Each ring was vibrated in eight different "positions," that is, with the. knife 

 edge bearing on eight different elements of the internal surface, corresponding to the eight 

 etched lines above referred to. The following tables summarize all the determinations of T for 

 both ring's, together with the corrections and reductions. 



King I. — Mori mum ruriutioiis of opjioxU,x about 0.0000^6. 

 [Radius=14 cm .409044. Thiekness = 15 ,mu .40.] 



Duration of 



swills;. 



5 l_'«i 28 



S 44 III) 



4 11 00 



5 33 00 

 ii 53 mi 



8 15 00 



4 29 411 



9 59 00 

 9 44 00 

 9 16 00 



3 56 00 

 9 42 12 



5 33 00 



7 03 00 



4 03 00 



6 31 00 

 9 50 00 

 9 53 00 



10 06 00 

 6 35 00 

 9 49 00 

 6 31 00 



8 37 00 



Temper- 

 ature. 



23. 15 

 23. 80 



2:;. 45 



23.70 

 23. 13 

 23. 10 

 23. 60 

 23. 30 

 22.70 

 2.".. 10 

 23. 30 

 27.90 

 23. 20 

 22. 50 



22. 50 

 2:;. 65 



23. 10 

 23. 40 

 23.20 

 23.60 

 23.05 

 23.80 

 22.85 



Mean for ! 

 eachposi- op] 



2507 

 2507 



2502 



2476 



2493 



2483 



2479 



247!) 



2480 



2460 



245D 



~24S3" 



Mean of all 

 positions. 



1. 002483 



Corrected 



for clock 



rate. 



1.002432 



Final corrected period=l s .0024165. 



