22 Mr. \V. Galbraith on Experiments of the Pendulum. 



making 86235"98 oscillations in a mean solar day at London, 

 at the temperature of 62° Fahrenheit, made SGlOrS^ oscilla- 

 tions at the Galapagos Isles, at the temperature of 68° Fah- 

 renheit. 



Number of oscillations at London 86235"98 



Correction for 68°, or 6° more than 62° 



= •4312x6° formula (6) — 2-59 



Number of oscillations at 68° 86333-39 



Number at Galapagos at 68° 86101-34 



Difference less 132-05 



Hence the seconds pendulum must be shorter than that at 

 London. 



"Whence by formula (1), as before, 



, .y 3913929 X 132-05 r^.nnccoTn 



we have AL= r^-rrr^ = — 0'11986870 



43110-7 



Correction from table, col. 2, for 130°*- —8830 



Prop, part for 2-05°^', col. 3, . . . — 289 



Equation, second difference . . . + 8 



Correction, col. 4, — 5 



Amount —9106 9 106 



Total correction — 0-11977764 



Length of pendulum at London . . . . 39-13929 



Length at Galapagos 39-01951 



At the temperature of 62°, or that at which the length of the 

 pendulum at London =39-13929 was obtained; and so on in 

 similar cases. 



Appendix. 



The French mathematicians generally give the length of 

 the pendulum according to their new system of weights and 

 measures. In this case the day is supposed to be divided into 

 100,000 seconds, instead of the 86,400 seconds according to 

 old custom. 



Now, since the lengths of pendulums are inversely as the 

 squares of the number of oscillations in the same time ; and 

 the length of the standard metre at the freezing point, com- 

 pared with Sir George Shuckburgh's standard scale at 62° 

 Fahrenheit, is, according to the accurate determination of 

 Capt. Kater, 39-37079 inches ; we can convert the French 

 measures readily into ours by the following formula : 



L= (^^y X I X 39-37079 = 52-74079/ (8) 



of Sir George Shuckburgh's scale; or 



L= 52-740564/ (9) 



of Bird's parliamentary standard of 1758, which is equal to 



36-00016 



