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DR. C. CHREB, EXPERIMENTS ON ANEROID BAROMETERS 



latter pair, for instance, the sums of the differences of the descending and ascending 

 readings were as follows : 



In devising the earlier groups of experiments, for comparing the two rates 1 inch 

 in 10 and 1 inch in 5 minutes, I did not at the time foresee the laws of the 

 phenomena, and so allowed equal lengths to the stoppages at the lowest point in the 

 two cases. The results are notwithstanding of considerable interest. Taking the 

 experiments over the range 30-21 inches, in order to allow for alterations in the 

 aneroids, I grouped them as follows : 



Group. 



I. 



II. 



III. 



Experiments Xos. 



6, 7, 18, 19 

 36, 39 

 56, 59 



Taking Group III. for example, the differences of the descending and ascending 

 readings at each inch were summed for the aneroids Nos. 2, 3, 4, 7, 8 in experiments 

 57, 58, and the ratios taken to the corresponding sums in experiments 56, 59. The 

 preponderance thus allowed to aneroids Nos. 2 and 3, in which the after-effect was 

 largest, is of little consequence, as all the aneroids showed the same general 

 phenomena. The results appear in Table XXXIV. 



TABLE XXXIV.- 



-Ratios Differences Descending less Ascending Readings 

 (l inch in 10 : 1 inch in 5 minutes). 



