38 NATURAL HISTORY OF KERGUELEN ISLAND. 



The force of the wind is figured on the scale usually employed on sea- 

 going vessels, according to which the maximum is 12, representing the 

 strongest possible wind, such as is experienced in a typhoon or hurri- 

 cane. According to this scale the force of the wind was three times 

 estimated to equal 11, and fourteen times 10, in violence. Such estimates 

 are of course liable to a certain personal error on the part of the observer ; 

 but it is not probable that in this case the error lies on the side of excess. 

 The average daily rain-fall for November was 0.205, and for December 

 0.252 inch, no rain-gauge having been set up previous to Ijfovember. 

 Both the rain and tide gauges were extemporaneous contrivances, con- 

 structed by Commander Eyan as soon as opportunity and leisure offered. 

 By the latter the rise and fall of the tide were measured with consider- 

 able accuracy, and were found to vary from 3 feet to 7 feet, according 

 to the season of the month, and partly to the direction and force of the 

 wind. The average rise of the tide was about 5 feet. 



MAMMALS. 



The only land-mammal found on the island is the common mouse 

 {Mus musculus), which abounds everywhere; doubtless imported by one 

 of the earlier sealers. It builds its nest in holes in sand-banks (in one 

 instance in the brain-cavity of the skull of a sea-elephant), lining it 

 with dried grass-stems or bits of oakum. From the husks of grass- 

 seeds scattered about the entrances to its burrows, I suppose these to 

 be its principal food. 



Upon Cat Island, one of those bounding Three Island Harbor, the 

 wintering-place of the sealers, the domestic cat has, for many years, 

 existed in a wild state. It lives in holes in the ground, preying upon 

 sea-birds and their young, and is said to have developed extraordinary 

 ferocity. Recent attempts to retame individuals, even when taken 

 quite young, have always, as I am informed, failed. I was not able to 

 visit Cat Island during the stay of the transit expedition, and therefore 

 am unable to say whether any obvious structural signs of reversion 

 were presented by these animals. 



Eabbits, swine, and goats have been introduced upon the Crozet and 

 some of the Kerguelen Islands from time to time, and have always 

 thriven well. Hog Island, the westernmost of the Crozet group, is 

 overrun with rabbits, which have also been introduced into Kerguelen 

 by the English transit party. 



