Besults of Some Expcriinents upon the Bate of Evaporation. 51 



1900 

 -January ... 

 February . . . 



March , 



April 



May 



June 



Ji^iy 



August , 



.September . . 



October 



November . . . . 

 December . . . , 



Wind 

 Excess. 



M. per clay. 

 + 80 

 + 113 

 + 113 

 + 50 

 + 95 

 + 71 

 + 77 

 + 198 

 + 145 

 + 229 

 + 93 

 + 89 



8-incli 

 Copper Pan, 



Inches. 



+ 



+ 



+ 

 + 

 + 

 + 



+ 



•067 

 •102 

 •055 

 •022 

 •005 

 •025 

 •065 

 •067 

 •156 

 •023 

 •246 

 •069 



Screened 

 Tub. 



Tank. 



Inches. 

 + -071 

 + -010 



— ^050 



— -013 



— ^019 

 + -002 

 + ^017 

 + ^044 

 + ^152 

 + ^020 



— ^222 

 + ^078 



Inches. 



Picbe 

 Tube. 



+ 



•017 



+ • 



— 



043 



+ • 



— 



030 



+ • 



— 



005 



+ • 



— 



008 



+ • 



+ 



008 



+ • 



+ 



027 



+ • 



+ 



•035 



4- • 



+ 



097 



+ • 



— 



019 



+ • 



— 



•152 



— • 



+ 



•006 



+ • 



Inches. 

 •023 

 •012 

 •020 

 •034 

 •005 

 •059 

 •091 

 •105 

 •174 

 •067 

 •235 

 •024 



That is, if we average the monthly numbers : — 



1. When the mean temperature of the day rises 7°*3 above the 

 monthly mean, the respective increases of evaporation are : — 



Inches. 



8-inch Copper pan + ^069 



Screened Tub + -044 



Tank + -027 



Piche Tube + ^059 



2. When the mean humidity of the day falls below the mean of 

 the month by 16 per cent, the respective increases of evaporation 

 are : — - 



Inches. 



8-inch Copper pan -\- ^117 



Screened Tub -f '086 



Tank + ^060 



Piche Tube +•121 



3. When the velocity of the wind for the day rises above the 

 mean daily velocity for the month by 113 miles per day, the respec- 

 tive increases of evaporation are : — 



Inches. 



8-inch Copper pan + •OOo 



Screened Tub + ^007 



Tank — -006 



Piche Tube + ^032 



These conclusions are not altogether satisfactory. The second 

 would seem rational enough ; but the numbers suggest that the first 

 is merely a sort of undercurrent of the second. And a hasty 

 inference from the third would be that the wind has no effect at all 

 upon the rate of evaporation, which, of course, is not in agreement 

 with what all reason and observation have assented to for many 



