MR. W. N. SHAW ON HYGROMETRIC METHODS. 



105 



No. 55. 



In this case no reason can be readily assigned for the difference. It must be 

 attributed to mere errors of observation, but the rapid and unusual variation of the 

 temperature of the saturator may account for part of the difficulty of obtaining 

 concordant dew-points. 



The other noteworthy cases are those in which the dew-point was higher than the 

 saturator temperature, Nos. 80, 73, 81, 67, and 48. In the first four of these experi- 

 ments I was paying special attention to the very faintest indications of the presence 

 of dew. I had come to the conclusion, from observations with DINES'S hygrometer 

 conducted in the manner detailed below, that it was possible to get a dew deposit 

 upon a glass surface at a temperature above the theoretical dew-point, and I was 

 endeavouring to ascertain if the same occurred with the REGNAULT instrument. It 

 would appear that to a certain extent that is the case. I give my observations 

 and notes for Experiment 81 : 



MDCocuutrvm. A. 



