POTSDAM II. 



At the conclusion of the whole programme of work in October, 1913, the pendulums 

 were again swung in Potsdam. ( )n t his occasion, they were observed in the middle cellar 

 on a " Feldpj'ailer " fixed with plaster of Paris to the solid cement floor of the cellar. 



Time. The break circuit clock used throughout this series was the same one as 

 used in the first series. The rate was determined in the ordinary way by 

 Professor Wanach and, after correction for barometer, this may be taken 



as : 



TABLE VIII. 



Sec. 



Oct. 43-05-5 p.m. ... 0-14 sec. daily. 



5 9-0 A-ll-5a.m. 0-13 



5 5-OP-7-Op.m. -0-U 



69-0 A-ll-5 a.m. -0-15 



6 4-OP-7-Op.m. -0-15 



79-0 A-7-Op.m -0-16 



M 7 4-OP-7-Op.m.... -0-17 



8 8-5 o-ll-O a.m -0-18 



Temperature. The temperature was given by thermometer 29110, reading to one- 

 fifth of a degree Centigrade, and was estimated by telescope to hundredths of 

 a degree. The errors were redetermlned by the Physikalische Technische 

 Reichsanstalt and found to be as follows : 



at 0C. .. .. 0-12C. 



,10C. 0-06 C. 



> too high. 

 20 C 0-08 C. 



30 C . . 0-10 C. j 



The total range of temperature during the observations was from 14 -47 C. to 

 14 -74 C. a difference of only 0-27 C. 



The greatest temperature change during the course of observations on any single 

 pendulum was 0-03 C., corresponding to a rate of change of 0-05 per hour. In this 

 series, the dummy pendulum rested, not on the brass block provided with the apparatus, 

 but on a cork disc of the same size a procedure which had been followed in all observa- 

 tions subsequent to those of July, 1911. 



Barometer. The barometric pressure was read by Aneroid Bohne 937, and a 

 correction applied to reduce to the true barometric height. The total 

 range of pressure was from 747-9 to 754-1 mm. Percentage humidity was 

 measured by a Koppe's hygrometer. 



19 B 2 



