64 



earth. The following table gives the mean temperature for the ten- 

 day periods ending on the dates given in column 1 and at a depth 

 of 1 foot below the surface of the ground. Temperatures are given 

 by them for other depths, as also for the air ; the total rain and snow 

 is also given. An investigation of the connection betw'een earth 

 temperature and the development of vegetation is being carried on 

 by them, but as no results have as yet been published I give merely 

 their soil temperatures at a depth of 1 foot, which usually agree, 

 within a degree centigrade, with the average temperature of the air 

 for ten days. 



.yean ioiiiicniturc of the soil at a depth of 1 foot for periods of ten days at 

 Montreal, Canada. 



This series seems to show the powerful influence of a snow covering 



to keep the ground from cooling to very Ioav temperatures during the 



'inter. The minimum temperatures at 1 foot depth were —0.5° F. 



u, ring the twenty days March 22 to April 10, 1889, and +0.-!° F. 



during tlie ten days March 17 to 2G, 1890. 



