230 Canadian Record of Science. 



galvanometer and a couple similar to those in the ground, 

 to make counection with the other wires at the switch- 

 board. The galvanometer is made to read zero on the circle 

 when the circuit is open, If now the circuit be closed at 

 the switch-board the needle will be found to deflect, but may 

 be brought back by bringing the inside couple to the same 

 temperature as that in the ground. For this purpose the 

 inside couple is immersed in water, or in winter, in a 

 mixture of snow and watar. "When the balance is 

 established, the temperature of the water is the same as that 

 of the ground at the depth of the outside couple. 



In this the first report upon the work of the committee, 

 it is proposed simply to place on record the results thus far 

 obtained, leaving to the future, such deductions as it may 

 be possible to draw. The temperatures in degrees centi- 

 grade — as given — are averages of ten-day periods, while 

 the figures for snow and rainfall express the total precipi- 

 tation for the same periods. The accompanying chart of 

 curves will exhibit the relations thus far established. 



The soil terminals of the thermometer are located at a 

 distance of about fifty feet from the air terminal, and about 

 twenty feet from the observatory. The depths thus far 

 operated upon are one, two, three and four feet from the 

 surface, a limitation imposed by the formation of the local- 

 ity — which is at present. the only one available within work- 

 ing limits of the instrument. 



The soil in which the instrument is placed, is a well- 

 drained and rather gravelly loam for a depth of four feet 

 three inches, at which point the bed rock is reached. It 

 will, therefore, be observed that the lowest point of obser- 

 vation is only about three inches from the rock. Grass 

 has been allowed to grow freely about the instrument, 

 though kept rather short, thus establishing the conditions 

 of land in sod. 



The observations recorded below have been taken by Mr. 

 E. H. Hamilton, B.A.Sc, assistant in the McGill College 

 Observatory. 



