20 



then described the human voice, and its affinity to wind 

 instruments ; demonstrated the variations of tone, according 

 to the vibratory motions of sounding bodies, as contained in 

 the old theory, with some remarks on the new ; and dwelt 

 on the separation of the general from the particular motion 

 effected, in order to prove the dependence of sound on 

 their union. He next treated of the motion of sound; its 

 different velocity through different mediums ; the causes of 

 echo ; the organs of hearing, exhibiting a representation of 

 their internal structure ; the labyrinth, internal fluid, au- 

 ditory nerve, and explained the action of sound on the ear; 

 and concluded with a summary of the subject. 



June 9. — The Kev. H. Lacey delivered a Lecture on 

 the Hibernation of Animals. In the introduction to his 

 subject he noticed particularly the purposes for which hi- 

 bernatins: animals chang-e their abode. He then considered 

 those animals whose hibernation consists in repose, which 

 he stated as one only of their several wintry conditions to 

 which their habits and instincts impelled them ; and observed 

 that the phenomenon of torpidity difl"ered according to the 

 difference of class to which the animals belong, and that it 

 was conformable to the effect which climate and other causes 

 produced. He then gave examples of hibernating animals 

 which do not fall into habitual torpidity, and of those torpid 

 and quiescent animals which, regulated by circumstances, 

 periodically undergo torpidity alike in cold and warm cli- 

 mates, observing that the latter admitted equally of torpidity, 

 though with some variety of circumstance, dependent on the 

 diversity of latitude in the diff"erent quarters of the globe. 

 The lecturer then treated of the hibernation of birds, parti- 

 cularly noticing the apparently well authenticated hy- 

 pothesis, that swallows during the winter season submerge 

 in ponds and lakes, and the leading modern authorities in 

 support of it, which, though advanced by persons of great 

 weight and veracity, was supported by very inconclusive 

 evidence. On many of the circumstances adduced to es- 

 tablish the hypothesis he commented with abilitj', observing 

 that, if true, they must be considered only as exceptions to 

 the general rule of migration, and as the aberrations of 

 nature; and shewed that by the construction of their organs 

 of respiration, by their specific gravity, &c. it was contrary 

 to physiological deduction. The inquiry as to the period 

 and country of their migration was reserved for a future 

 occasion. Mr. L. next took a hasty glance of reptiles, 

 worms, and insects — noted the circumstances of some of 



