68 FACULTIES OF BIRDS. 



Apuleius compares a glutton smelling out a good 

 dinner as superior in such sagacity to the dog or the 

 vulture. 



It may well be disputed, however, that the smell 

 of the vulture or any other bird extends to the dis- 

 tances alleged by these writers, for, as was long ago 

 remarked by Caelius Rhodiginus, odorous effluvia 

 cannot be distinguished at any considerable distance, 

 as they are not only diluted by being diffused in the 

 air, but may even be thereby wholly changed in their 

 qualities*. The observations of Avicenna are still 

 more to the point. " Odours," he says, " arise from 

 most animals as well as from man ; and in a similar 

 way things are rendered visible at a considerable 

 distance, even beyond high mountains. I have myself 

 indeed observed vultures wheeling about in the air, 

 and of course their vision must be extensive, to 

 enable them to see from a higher elevation than the 

 highest mountains, since they can in such circum- 

 stances discern a piece of carrion in the plains below 

 them. But if it is denied, that colours can be per- 

 ceived at such distances, much more ought the same 

 to be affirmed of odours, whose power is weaker 

 than that of colours ; and since it is not indispensable 

 for every animal to move the eyelids or the eyes in 

 order to see, neither is it indispensable for every 

 animal to smell to a thing in order to perceive the 

 scent thereof f. 



From all these various facts we think Dr. John- 

 son's remarks are decidedly the most plausible ; and 

 even those authors who speak in the most unhesi- 

 tating manner of the powers of smell, furnish from 

 their own accounts circumstances to prove their opi- 

 nions doubtful. Wilson, for example, speaking of 

 the turkey -vulture (Caihartes aura, ILLTGER), says, 



* Lect. Antiq. viii. 18. 

 f Apud Aldrovandi Ornithol. i. 12G. 



