382 Miscellanies. 



according to Mr. Oersted, must be accounted for by the circumstance, 

 that in Mr. Perkin's experiments, the compression was produced by 

 percussion, the force of which cannot be calculated. — Idem. 



8. Proportion betiveen the metre and English yard. — M. Fran- 

 coeur, in an elaborate memoir "on the proportion between French 

 and English measure" has found that the metre is equal to 39.37079 

 English inches, and the English imperial yard equal to 0"*. 9 1438348 

 numbers which may be relied on whh the utmost confidence. 



9. Dip of the magnetic needle at St. Petersburgh. 

 Observed by M. Hansteen in June 1828, 71° 17.3' 



By M. de Humboldt, (applying an instrumental cor- 

 rection) in May ] 829, - - - - - - 71° 14.5' 



By M. de Humboldt in December 1829, - 71° 11.5' 



" M. KupfFer in May, 1830. - - - - 71° 11.3' 



It would appear from these observations, that the annual decrease 

 of the dip at St. Petersburgh is about 3'. 



NATURAL HISTORY. 



On habits of cleanliness in birds ; by W. Ainsworth. — It is 

 a fact, not generally known, that the claws of birds are used as combs 

 to rid the plumage of vermin ; whence birds which have short legs 

 are most infested by insects. The expedients, which birds, charac- 

 terized by short feet, — the waders which, from the inflexible nature of 

 their legs, and the geese tribe, from the opposition to scratching, of- 

 fered by the membrane between the toes, are put to, in order to get 

 rid of their vermin, are well dserving of attention, as illustrating the 

 ingenuity of animals, and the curious provisions made by nature for 

 their cleanliness. When birds, by accident or imprisonment, are 

 deprived of the natural means of ridding themselves of vermin, they 

 often fall victims to their attacks. The author, walking on the coast 

 of Northumberland, disturbed a bird which flew heedlessly, as if inju- 

 red. On shooting it, he found it was covered vs^ith vermin, especially 

 about the head, and on further examination ascertained that it had lost 

 one leg, and was thus deprived of the means of ridding itself of these 

 insects. A nest of young swallows had been hatched and they had 

 attained considerai)le size when a change was made in the window, 

 which frightened the parents ; from that time they continued to feed 

 their offspring, but never entered the nest. The young ones soon 



