48 



March 090 inches 



June 04S „ 



September 067 ,, 



December' 07(1 „ 



Me;in for four months 0G7 „ 



T1k's(> ninnbers have tlie same relativ'e ma^nit.tule as the monthly ranges for 

 llie cnrresiiouiliiig months, except tliat June anil Sejiteml^r h:ive changed places. 

 But on June 7tli, the barometric readings for which are omitted in the reduction 

 of the hourly observations, the barometer was unusually low, and had it been 

 ]iossihle to have made use of the records for that (hiy the diurnil range; for June 

 would have been greater than that given above. 



The temperature curves show great regularity as to their ]iiiints of maxima 

 and minima. The maximum temperature occiu-s at 3 p in. in all of the moiiths 

 anil the minimum at 6 am. in March and September, at 5 am. in June and at 

 7 a.m. in December. 



From table T the mean daily r.inge is found to be as f jIIows; 



March 13°.2 



June 9°.S 



Septend.er 11°.4 



Deceudier lß°.7 



Mean for four months 12°. G 



These numbers have the same relative magnitudes as those rejiicsenting the 

 maximum daily range for the corresponding months, from the regular series. 



The two pages of chart Number 20 contain curves representing the hourly 

 means of the percentages of humidity observed (bu'ing the same four months. 

 This element is liable (o frequent and considerable disturbances from accidental 

 or non-periodic causes and the curves are, therefore, less regular than those repre- 

 senting temperature. They exhibit the same general form, however, and follow the 

 inverse movement of the thermometer very closely. The daily range is as follows; 



ÄLirch 24 per. cent. 



June IS „ „ 



September 25 „ ,, 



December 35 ,, ,, 



From mean curve 25 ,, ,, 



It will be seen that the range is greatest when the actual percentage of 

 humidity is least, and least when it is greatest. It appears from these cm-ves 

 that there is a time in the early morning, generally from 1 a. m. to 7 a. m., 

 during which the percentage of humidity does not vary greatly and that the 

 fall in the percentage of humidity lags somewhat behind the rise in the thermometer. 



