^36 



Explanations — Column 5 contains corrections for change of 

 temperature obtained by multiplying 0*004 by the number 

 which the degrees in column 4 exceed 32. From an inspec- 

 tion of columns 2, 3, and 4 it appears, that the readings of 

 the Aneroid compared, are more in excess of the Standard in 

 an elevated than in a low temperature, and that the variation 

 from this cause equals about 0'004 inch for one degree of 

 Fahrenheit. It also appears that the readings of the Aneroid 

 are more in excess of the Standard with a high Barometer 

 than they are with a low Barometer, and that the variation for 

 one inch arising from this cause is equal to about 0*15 inch. 



Column 6 contains corrections for change in the height of 

 the Barometer, obtained by multiplying 0*16 by the number 

 which the readings of the Aneroid in column 2 are above or 

 below 30'00 inches. 



It will be seen that the change of temperature to which the 

 Aneroid was exposed during the trial was 50°, and that the 

 range of the Barometer was 1'58 inch. The extreme error of 

 the Aneroid produced by these changes was about half an 

 inch, when uncorrected for change of temperature and error of 

 scale. When corrected for change of temperature and error of 

 scale, as above described, the extreme error in the readings of 

 the Aneroid did not exceed a twentieth of an inch, an amount 

 scarcely exceeding the probable error from the reading of the 

 scale. The smallest division on the scale was one-twentieth 

 of an inch, but I read to the nearest hundredth of an inch by 

 estimation. 



J. H. 



Thus closed the public meetings of the Society. 



