— 3 — 



For the sake of convenience ±he dimensions of the peudnlums are given 

 in the following tabular form. 



Pexdulum. 



B. 



C. 



E. 



Total lenrth 



122.0 cm. 



111.0 „ 



12.5 „ 



4.2 „ 



2.5 „ 



3574. gr. 



122.2 cm. 



115.1 „ 



12.3 „ 



4.1 „ 



2.5 „ 



4356. gr. 



111.0 cm. 



110.0 „ 

 12.0 „ 



4.0 „ 



2.1 » 

 2834. gr. 



Distance between knife-edge 

 and end of pendulum 





Diameter of cylindrical stem 





CORRECTIONS. 



Corrections for the arc of oscillation, temjDerature, and chrono- 

 meter rate, were applied as on the previous occasions. For the arc, Basevi's 

 formula — t/ö4. {CL+ ß — |a — /i ) was employed. To savo the labours of com- 

 putation, tables of corrections for each pendulum were made with two 

 arguments, the mean arc of oscillation and the difference of the arcs 

 of oscillation. Temperature correction was applied so as to reduce all the 

 observations to that at 20° C which was about the mean for all the experi- 

 ments, the coefficient of expansion of brass being taken as 0.0000187 per 

 degree. With regard to the chronometer correction as only the average rate 

 betw^eja the two times of observation could be obtained, care was taken to dis- 

 tribute, as far as possible, the pendulum experiments throughout the full period 

 for which this average rate was applied. Observations were made twice 

 every 24 hours when feasible ; and from these observations the average rates 

 for night aJid day were determined. Gauss's metliod of determining the 

 azimuth, coUimation, and clock error from G to 12 star observations was follow- 

 ed. 



AVc began experiments at 'J'okio in the middle of July in the Pendulum 

 Room of tlio Physical Ijaboratory of Tokio University, and having completed 

 our preparations, wc loft Tokio ou the 5th of August reaching the island on 

 the 10th of the same month. As the ship was expected to stay only for about 

 10 days, we took with us a prepared set of masonry and wooden piles to lose as 

 little time us possible in building stuno piers for pendulum, transit ijistrumcnt, 

 magnetometer and declinometer. 



Through the kindness of Mr. T. Minaiui the Governor of the Island, wo 

 wero furnished with a building, in the village of Ogiura, for our experimental 



