POTSDAM I. 



OBSERVATIONS BY PROFESSOR HAASEMAXX ix MAY. 1910, IN EAST CELLAR. 



Latitude, 52 22' 9 N. Lout/ ;/<!<>. 1 3 03' 9 E. 

 Height above sea-level. 83 metres. 



Clock rate. For the initial observations at Potsdam, one of the Observatory clocks 

 (Riefler 96) was used in comparing the time of swing of the pendulums. The rates of 

 this clock were determined in the usual way by comparison with the standard clock 

 of the Observatory, and were given as 



May 18th and 19th .. .. -0- 05 daily. 



19th 20th .. .. -0-02 



20th .. 21st .. -0-02 



23rd -0-05 



24th -0-02 



The probable error may be taken as less than 0-01 sec. daily. 



Temperature. The temperature, given by a thermometer divided in fifths, was 

 read by an auxiliary telescope and estimated to hundredths of a degree. The corrections 

 to be applied to the thermometer are given below : 



P.T.R. 1. ',!>.->.-, at C., correction -0-04C. 



10 C., -0-04C. 



20 C., ... -0-04C. 



30 C., -0-04C. 



40 C., -0-04C. 



The total range of temperature during the series of observations was from 13 -22 C. 

 to 13 -74 C., a variation of 0-52 C. 



liarometer. For a calculation of the barometric reductions, the readings of aneroid 

 barometer Bohne 937 were taken and the correction 5-6 mm. applied. The total 

 range during the observations was from 752 to 758 mm. 



Hygrometer. A Koppe's hair hygrometer was used in this series. 



Flexure. Observations for flexure were made as under : 



May 16th .. .. Xos. 5 and 7, 42 10~ ; ; No. 21, 52 10~ ; . 



16th .. ., 44; 49. 



28th .. 44; 51. 



The corrections applied are 43xlO~ 7 sec. for 5 and 7, and 51 xlO~ 7 sec. for No. 21. 

 The analysis of Professor Haasemann's results is given in Table I. 



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