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.—Jdem. 
8. Proportion between the metre and English yard.—M. Fran- 
ceur, 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”.91438348 
numbers which may be relied on with 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 1829, - - - - - - 71° 14.5 
By M. de Humboldt in December 1829, - 719 11.5 
“ M. Kupffer in May,1830. - += - = 7911.3 
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. ArnswortH.—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 with vermin, especl"Y 
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 considerable 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 
