DEPTH TO WHICH THE GROUND FREEZES 29 



1875. Mains for water supply are usually put 2 ft. 

 below the surface to avoid all risk, and I remember, 

 but cannot give details, that in a small Hertfordshire 

 town an engineer did the economical and put his 

 pipes at one foot. A big frost came, and every main 

 was cracked ! ' 



It is a comfort to know that our water-main is 

 tolerably safe. As to underground larvae, Mr. Symons 

 adds : " I should think that larvae in walls, etc., 

 generally get below 32, but that those that get down 

 6 in. underground very rarely do so perhaps one 

 year in five." 



So I wrote on Jan. n. The next few weeks were 

 instructive. In the first place the underground 

 temperatures of the spring of 1895 greatly extended 

 the maximum depth at which a freezing temperature 

 was ascertained. The thermometers showed that 



Frost penetrated to i ft, at 1 1 stations. 



i ft, 6 in. 3 



2 ft. i station. 



2 ft. 6 in. no station. 



While this was the story tolcl by the thermometers, 

 the water-mains indicated an even greater penetration 

 of the frost. At Maidenhead, Hatfield and Shrews- 

 bury the mains froze at 2 ft. 6 in., and at Musselburgh 

 at over 3 ft. The damage done all over the country 

 was very great. In Liverpool 27,000 houses were 

 without water at one time. In Sheffield nearly 

 170,000 persons were without proper water-supply. 

 Selkirk reported that so many bursts had occurred 

 that no attempt would be made to repair, but new 



