SMELL. 247 



has been commonly asserted of vultures, and also 

 of the goose. In a case of this sort, observation is 

 always better than the most ingenious and plausible 

 theoretical reasoning ; and fortunately we possess, 

 with respect to the vulture and some other birds, 

 the remarks of Dr. James Johnson, which we have 

 already partially referred to. " It has always," 

 says the doctor, " appeared to us most extraordi- 

 nary, indeed unaccountable, that birds of prey could 

 scent carcasses at such a distance as they are said 

 to do. We were led to skepticism on this subject 

 some twenty years ago, while observing the con- 

 course of birds of prey from every point of the hor- 

 izon to a corpse floating down the river Ganges, 

 and that during the northeast monsoon, when the 

 wind blew steadily from one point of the compass 

 for months in succession. It was extremely diffi- 

 cult to imagine that the effluvia from a putrefying 

 body in the water could emanate in direct opposi- 

 tion to the current of air, and impinge on the olfac- 

 tories of birds many miles distant. Such, however, 

 were the dicta of natural history, and we could only 

 submit to the general opinion. We have no doubt, 

 now that we know the general opinion to be some- 

 thing wrong, that it was by means of the optic 

 rather than the olfactory nerve, that these birds 

 found out their quarry. 



"It has been ascertained by direct experiments, 

 that where any putrid carrion was enclosed in a 

 basket, from which effluvia could freely emanate, 

 but which concealed the offal from sight, it attract- 

 ed no attention from vultures and other birds of 

 prey till it was exposed to their view, when they 

 immediately recognised their object, and others 

 came rapidty from different quarters of the horizon, 

 where they were invisible a few minutes before. 

 This sudden appearance of birds of prey, from im- 

 mense distances and in every direction, however the 

 wind may blow, can only be accounted for by their 



