538 



MR OMOND ON OBSERVATIONS AT THE 



house than in the Observatory thermograph screen, while the mean of the two, 

 — — — , is higher in summer and lower in winter. Also the dry bulb temperatures 



at the Schoolhouse are higher than at the Observatory during the day and lower in the 

 morning and evening. Thus both the daily and yearly range of temperature is slightly 

 the greater at the Schoolhouse, a consequence of the more confined situation of the 

 thermometers there, and of the fact that the thermograph screen at the Observatory is 

 against a wall. Comparing the maximum and minimum temperatures in the Stevenson 

 screen at the Observatory with those at the Schoolhouse, we get the following- 

 differences on the average of the months of 1891: — 



Difference of Schoolhouse Stevenson from Observatory Stevenson Screen in 1891. 

 Schoolhouse higher in heavy type : Schoolhouse lower in italic type. 





Jan. 



Feb. 



Mar. 



April. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Year. 



Max. . 



■5 



•1 



I 



7 



12 



2-2 



1-4 



11 



•8 



■8 



■4 



■4 



•4 



Min. 



•5 



■1 



•4 



■8 



m 2 



1-0 



■8 



■6 



■o 



■4 



•1 



■9 



•3 



Max. + Min. 



■0 



■1 



•2 



•0 



•5 



•6 



•3 



•2 



•4 



•6 



•2 



•6 



1 



2 



thus showing that the differences in the large table are partly at least due to the 

 situation of the thermometers at the Observatory and Schoolhouse, and not merely to the 

 different patterns of screen employed. 



Summary for the year 1891. 



] Hfference of Schoolhouse maximum from Observatory thermograph maximum, . . . +1°'3 



„ „ minimum ,, ,, minimum, . 



„ ,, maximum from Observatory Stevenson maximum, . 



minimum 



minimum, 



-r-3 



+ 0°-4 

 -0°-3 



Barometer. — In the table the average difference for each month of the Schoolhouse 

 barometer from the Observatory barograph is given in thousandths of an inch, for each 

 of the five hours at which readings were taken at the Schoolhouse. A general mean for 

 each month and for each hour of the year 1891 appears at the side and foot of the table. 

 On the average of the whole seventeen months, the Schoolhouse is 0'0069 inch below 

 the Observatory. In August 1892 the Schoolhouse barometer was hung alongside of 

 the Observatory standard for four days, and a series of comparison readings taken by 

 the Observatory staff. On the mean of these readings the Schoolhouse barometer was 

 - 0068 inch below the Observatory one. This difference of practically 0*007 inch 

 between the barometers is due to a difference of the instrumental corrections of the two 

 instruments. 



Rainfall. — The gauge used at the Observatory is a self-recording Beckley (see 



