458 



DR. C. CHBEE, EXPERIMENTS ON ANEROID BAROMETERS 



Considering the limited number of experiments, the irregularities in the tables are 

 by no means surprising, when we reflect that even at 15 inches pressure the average 

 fall of reading in 10 minutes was only about '07 of an inch for aneroid No. 1, 

 and '03 of an inch for aneroid No. 4. In the case of the readings after 2 or 4 minutes' 

 exposure to pressures such as 26 or 24 inches, the uncertainty is of course much 

 greater. It will be noticed that the figures for aneroids Nos. 1 and 3 are very 

 similar and are approximately double the figures for No. 4. 



17. Subsequently three experiments, Nos. 33, 34, and 35, were devoted to 

 elucidating the law connecting the fall of reading with the time elapsed since the 

 stationary pressure was reached. Pressure was reduced at the normal rate, 1 inch 

 in 5 minutes, but kept for 2|- hours at the lowest point of the range, readings 

 being taken at intervals. The lowest pressures in these three experiments were 

 respectively 24, 21, and 18 inches. It would occupy too much space to give full 

 details, but Tables XL and XII. show the falls observed at 30-minute intervals. 

 To avoid decimals the observed falls are multiplied by 10 4 /range ; so, to deduce the 

 falls in inches, the figures in the table must be multiplied by n X 10" 4 , where n is 

 the number of inches in the range. 



TABLE XI. Fall at Lowest Pressure X (I0 4 /range). 



TABLE XII. Same quantity as in Table XL 



