Sh(rt't Commmiications : — Mammifera. 455 



While on this subject, I may observe, in regard to high, 

 exposed, and sloping grounds escaping the effects of hoar- 

 frost, while low grounds suffer, that, in addition to the causes 

 that have been assigned, it may be the case that the cold 

 stratum, as fast as it is formed in such situations, may, from its 

 increased density, slide down to the lower levels, and be 

 replaced by a warmer stratum, and so on ; thus helping to 

 produce the destructive effects of frost in low situations, so 

 often noticed. 



Vale of Alford^ Aberdeenshire, Nov. 20. 1834. 



Art. XII. Short Communications, 



Mammtferous Animals. — Perforation of a Leaden Pipe 

 by Rats. — The sharpness of the incisory teeth of the Glires, 

 and the power with which these animals can employ them, are 

 well known to those who have unfortunately allowed a finger 

 to come within the range of those of any one of the species. 

 How readily will a squirrel penetrate the hardest shells of a 

 nut; and how do we hear, night after night, the patient and 

 persevering grinding of a rat's teeth, working its way through 

 some particular plank or joist below a skirting-board, forming 

 a barrier interrupting the intruder in its progress towards a 

 larder, storeroom, or closet, wherein its instinctive shrewd- 

 ness assures it that its labour will meet with a plentiful 

 reward ! It was not, however, till very lately, that I had 

 learned to what extent rats will employ their teeth, when bent 

 on making their way towards a desired point, whatever be the 

 nature of the intervening obstacle. 



The facts of the case which informed me of this are the 

 following : — The kitchen and scullery, &c., of a gentleman's 

 house, were supplied with water from a pool at some distance, 

 by means of a leaden pipe about I J in. in external diameter, 

 with a bore of about | in. in diameter ; thus leaving a solid 

 circumference of metal varying from J in. to f in. in thickness. 

 This pipe, on reaching to the building, was carried under a 

 flagged pavement, and embedded in brickwork, till it termin- 

 ated in a cock, at a convenient height, for the purpose of 

 affording the supply of water. For some months in the sum- 

 mer the pool of water had been intentionally lowered while 

 some improvements near its banks had been carried on, and 

 the pipe had, in consequence, never been used. I know not 

 how far this circumstance influenced the operations of the 

 rats, whose avidity for water, more especially in dry weather, 

 is such as to induce them to lay aside their usual shy and 



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