OF ARTS AND SCIENCES. 329 



As a check upon the observations with 0, a Centigrade thermometer, 

 marked No. 1, was read in connection with it. The corrections to 

 No. 1 were found from a comparison with to be as follows : — 



T No. 1 T No. 1 T No. 1 



o o o o o o 



—0.50 12 —0.94 21 —0.72 



3 —0.67 15 —0.97 24 —0.50 



6 —0.78 18 —0.90 • 27 —0.63 



9 —0.90 



The standard designated T 61 was received from Dr. Waldo in 

 October, 1882. Since this date all comparisons have been made with 

 reference to this standard. The following Report accompanied the 

 standard : — 



"The Obsekvatort of Yale College. — Thermometkic Bcreau. 



"Examination of the Y. 0. S. Thermometer, No. 61, made by Tonnelot. 



"1st. This thermometer has been examined in a vertical position 

 with the metallic scale and tube immersed in water having the tem- 

 perature of the bulb. 



" 2d. When the correction is + it must be added to the thermometer 

 reading, and when — it must be subtracted. For example, suppose 

 the thermometer to register 81°.0 and the respective tabular correc- 

 tions at 72° and 92° to be — 0°.5 and — 0°.7, then the corrected read- 

 ing of the thermometer would be 81°.0 — 0°.6 = 80°.4. 



" The theoretical mercurial standard thermometer to which this in- 

 strument has been referred, is graduated by equal volumes upon a glass 

 stem of the same dimensions and chemical constitution as the Ivew 

 standards 578 and 584. The permanent freezing point is determined 

 by an exposure of not less than forty-eight hours to melting ice, suji- 



