I 



Tin; ACCIi LHRATK )X 



DUE TO 



THE FORCE OF GRAVITY 



AT 



TOKIO-JAPAX. 



Experiments for determining the value of tlie aeeeleration due to tlie force 

 of "Tiivity at Tokio were liegiui in tlie Physical Lahoratory iif the Iiii[ierial L'ni- 

 versity in the montli of Febniary 1880 and were continned at intervals during 

 the succeeding two or three months. The task of making tiie pendnlum vibra- 

 tions and the necessary measurements was assigned to Jlessrs. Tanakadate 

 and Tanaka, two sixjcial students in the Dei)artment of Physics. I\Iuch time 

 was given to preliminary experiments and time determinations in order to 

 familiarize these students with the use of the apparatus and also to develop 

 the most desirable method of reaching accurate results. 



A considerable series of experiments was made in the beginning with a 

 Kater's reversible pendulum belonging to the physical laboratory, the results of 

 which were only useful as furnishing an approximate value. Indeed the inve.s- 

 tigation by this method was not carried to any degree of accuracy on accoimt nf 

 the im[)0ssibility of obtaining an accurate measure of the length of the pendulum, 

 as the University [assessed no stiindard measure with which it could be compared, 

 as well as ou accmnit of the difficulty of iletermining certain corrections for the 

 influence of the atmosphere. It was resolveil, however, to attempt a more pre- 

 cise detennination by means of a so-calleil simple pendulum which had been 

 ordered from Salleron in I'ari.s and whicli arrived in time for tlie comi)letion of 

 the experiments in May. 



