462 



DR. .0. CHREE, EXPERIMENTS ON ANEROID BAROMETERS 



TABLE XVI. Recovery after Conclusion of Pressure Cycle, Values of D,/D . 



In dealing with Table XVI. one must bear in mind the smallness of D in the 

 shorter ranges, especially in the case of aneroid No. 4. The law of variation of a 

 quantity of the size '03 or '04 of an inch is difficult to ascertain with great exactitude 

 unless one can read to much less than '01. The figures, as they stand, certainly 

 suggest that in its early stage the recovery was distinctly more rapid in the case of 

 the shortest range than in any other. Since, however, there is no trace of a like 

 phenomenon in the next shortest range, its reality is at least doubtful, and I should 

 be disposed to attribute it to experimental errors. 



Over the other ranges the law of recovery is unquestionably almost, if not exactly, 

 identical ; and if, instead of grouping the results under pressure ranges, one had 

 grouped them under the several aneroids, one would have found that the mean 

 results were almost identical for the four. Thus, in deducing the law of variation, I 

 combined the results from all the aneroids, utilising all the ranges except the shortest. 

 The mean values thus obtained are compared in Table XVII. with values calculated 

 from the formula 



D,/D = (1 + t X -1357)- 



(9), 



