OP ARTS AND SCIENCES. 



101 



TABLE I. — Comparison of Tait Gauge, No. 0, and Bourdon Gauge. 

 Aq = .27 cm. ; A^ = .50 cm. ; L — 100 cm. ; p = .034 cm. 



15. The table contains five series of observations made at the times 

 (minutes) stated. In the first four series, I went up to the maximum 

 (1,000 atm.) and down again gradually, but not slowly. In the 

 last, I operated as fast as the experiment would permit. To deter- 

 mine the degree of accuracy, the rates at the bottom of the table may 

 be consulted. These show that a mean displacement of .0171 cm. of 

 the meniscus takes place in the pressure increasing series, for each 

 atmosphere. Considering data on the same horizontal row, it appears 

 that the differences of reading of the new gauge corresponding to a 

 given reading of the Bourdon gauge are greatest in the region of 

 low pressures. At zero the maximum difference observed is .40 cm., 

 equivalent to an error of 24 atm. Again, comparing the two zero 

 readings of the last column, the difference of reading is .56 cm., corre- 

 sponding to 33 atm. This, therefore, is a maximum index of the 

 inaccuracy of the new gauge, due to the thermal effects of compres- 



* Break in the measurements. 



