CRACKING OF TIMBER DURING INTENSE FROST. 329 



thing of the kind it is not easy to convey an adequate 

 idea of it. Strange to say, contrary to all that might 

 be expected, it bears a close resemblance, in many of 

 its leading conditions, to those produced by great heat. 

 Woodwork and all articles of horn, bone, or ivory 

 will shrink and crack for instance, during an arctic 

 winter, * exactly as when exposed to a hot sun or to 

 intense dry heat, and the fittings of cabins, etc., on 

 board ships, will open and warp, quite as much as, or 

 even more than, during a voyage to the tropics. 

 Beams and other heavy scantlings of timber will also 

 frequently suddenly crack, with a loud report, resembling 

 a rifle shot, especially if in a green state, as for 

 instance in the case of logs used in the construction 

 of houses. Even growing trees will often be heard 

 to crack (or explode) in a similar manner, during the 

 prevalence of intense frost, such as occurs periodically 

 in the forests of Canada, and in other localities with an 

 extreme rang'e of temperature. These facts are so 

 well known to all travellers and settlers in North America, 

 that it seems hardly necessary to do more than state 

 them. Mr. Rowan for example in his well-known 

 book, written for emigrants and sportsmen in Canada, 

 when giving a description of a hunter's winter camp 

 in the forest, says : " Suddenly a loud sharp report, 

 close by, wakes him. What is it? A rifle shot? No 

 simply a tree, cracking with the frost. " These noises 

 he thinks " are not caused by the freezing of the sap, 

 for " (he adds) " I have heard the same cracks in dry 

 seasoned timber, in the wall of a house." f 



* See Sir John Richardson's Boat Voyage through Ruperts Land, 

 1851, Vol. ii, p. 101. 



f The Emigrant and Sportsman in Canada Experiences of an Old 

 Settler, by John J. Rowan, 1876, p. 294. 



