OP ARTS AND SCIENCES. 



117 



Appendix to Thermometry. 



The last of January, 1879, Mr. S. W. Ilolman, of the Massachusetts 

 Institute of Technology, came to Baltimore to compare some ther- 

 mometers with the air thermometer; and by his kindness I will give 

 here the results of the comparison which we then made together. 



As in this comparison some thermometers made by Fastre in 1851 

 were used, the results are of the greatest interest. 



The tables are calculated with the newest value for the coefficient 

 of expansion of glass. The calibration of all the thermometers, except 

 the two by Casella, has been examined, and found good. The Casella 

 thermometers had no reservoir at the top, and could not thus be readily 

 calibrated after being made. The Geissler also had none, but I suc- 

 ceeded in separating a column. 



The absence of a reservoir at the top should immediately condemn 

 a standard, for there is no certainty in the work done with it. 



TABLE XXII. — Seventh Series. 



* The original readings in ice were 58.68 and 58 45, to which .15 was added 

 to allow for the pressure of water in the comparator. This, of course, gives 

 the same final result as if .15 were subtracted from each of the other tempera- 

 tures. No correction was made to the others. 



t Probably some error of reading. 



