50 Transactions of the South African Philosopldcal Society. 



would have a temperature curve vibrating in opposite phases to that 

 of the humidity curve ; and might therefore be antecedently expected 

 to show high temperature numbers, shows no very great departure 

 from the mean. 



Such a fact is worth looking into somewhat more closely. So let 

 us take in turn the highest mean temperature of the day during each 

 month, the lowest mean humidity, and the greatest daily wind move- 

 ment (each is obtained from hourly observations), and compare them 

 separately with the respective evaporation on the same day from the 

 different gauges. The results, in positive departures from the mean, 

 are given below : — 



1900 



January * 



January 



February 



March ! + 



April 



May 



June 



July 



August 



September 



October 



November 



December 



Temp. 



Excess. 









+ 



5 



+ 



5 



+ 



(> 



+ 



4 



+ 



9 



+ 



5 



+ 



9 



+ 



9 



+ 



8 



+ 



11 



+ 



11 



+ 



7 



+ 



6 



8-incli 

 Copper Pan. 



Screened 

 Tub. 



Inches. 

 + -147) 

 + -127) 

 + -038 

 + -065 

 + -112 

 + -005 

 + -035 

 + -055 

 — -023 

 + -056 

 + -097 

 + -164 

 + -019 



Inches. 

 + -121) 

 + -0711 

 + -030 

 •000 

 + -063 

 + -001 

 + -032 

 + -047 



— -036 

 + -072 

 + -070 

 H- -128 



— -022 



Tank. 



Inches. 

 + -129) 

 + -083) 



— -018 

 + -025 

 + -053 

 + -007 

 4- -012 

 + -017 



— -040 



— -001 

 + -002 

 + -064 

 + -013 



Piclie 

 Tube. 



Inches. 



+ 



033 



+ 



103 



+ 



032 



+ 



060 



+ 



0()4 



+ 



005 



+ 



059 



+ 



091 





005 



+ 



114 



+ 



107 



+ 



125 







026 



Humidity 



Excess. 



1900 



January 



February 



March 



April 



May 



June 



July 



August 



September . . . 



October 



November 



December 



— 20 



— 17 



— 21 



— 15 



— 9 



— 14 



— 19 



— 17 



— 11 



— 13 



— 14 



— 22 



8-inch 

 Copper Pan. 



Inches. 

 + -147 

 + -158 

 + -155 

 + -112 

 + -035 

 + -045 

 + -065 

 + -117 

 + -150 

 + -157 

 + -074 

 + -179 



Screened 



Tub. 



Inches. 



+ 



071 



+ 



140 



+ 



090 



+ 



063 



+ 



021 



+ 



032 



+ 



027 



+ 



064 



+ 



152 



+ 



140 



+ 



098 



+ 



128 



Tank. 



Inches. 



+ 

 + 

 + 

 + 



+ 

 + 

 + 

 + 

 + 

 + 

 + 



•044 

 •057 

 •079 

 •053 

 •002 

 •016 

 •012 

 •069 

 •097 

 •111 

 •083 

 •102 



Piche 

 Tube. 



Inches. 



+ 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 



•153 

 •152 

 •120 

 •074 

 •045 

 •089 

 •111 

 •105 

 •174 

 •147 

 •135 

 •144 



* There chanced to be two days in January each with the highest mean tempera- 

 ture of the day for the month. 



