108 MR. W. N. SHAW ON HrGEOMETRIC METHODS. 



After Experiment 78. Saturator reading, 8 - 00. 



DINES : Water run through slowly, dew appeared at the 

 first edge (nearest to the entering water) at 9'6 ; 

 water stopped : temperature gradually sank to 9'00, 

 and dew appeared at the other end, the first deposit 

 vanishing. The second deposit was visible only in the 

 best light and vanished without any measurable altera- 

 tion of temperature. Observation repeated : Dew 

 found at first edge at 9'72, but no dew formed on 

 other parts, although the temperature was reduced 

 to 9'06. The temperature was run down to 7'78 

 before anything like a wide deposit of dew was formed. 

 An estimate of 8'3 was made as the dew-point, and 

 confirmed by repetition of the observation. 

 79. Saturator reading, 11'61. 



DINES : Dew at further end at 15'61. Thermometer went 

 down without any more cold water to 13"6, and the 

 dew extended partly over the glass. Dew at both 

 ends at 13'06; vanished from the one end without 

 alteration of temperature ; disappeared altogether, 

 although the thermometer fell to 12'67. 

 80. Saturator reading, 13'83. 



DINES : Observation taken without air being drawn 

 through, i.e., without circulation ; a deposit was 

 formed at the near end only at 9'28. 

 81. Saturator reading, 14'51. 



DINES : Temperature reduced to 1 4 0- 00 without drawing 

 any air through ; on starting the air, dew was deposited 

 at first on the edge nearest to the air inlet, and it 

 gradually extended over part of the glass surface 

 without alteration of temperature. 

 82. Saturator reading, 0'80. 



DINES dew-point, 1 0> 22. 



With ice only, the temperature of DINES could not, be 

 reduced below 1'22, at which temperature the dew 

 was just visible. Calcium chloride and sodium chloride 

 were then added to the ice, and the following observa- 

 tions made. The faintest visible deposit was at 1'2. 

 Cooling down to 0'56 increased the deposit, but not 

 very greatly. This was repeated many times, and in 

 one experiment the thermometer was taken down to 0, 



