cxxviii LIFE OF WILSON. 



The " Memoir on the Migration and Torpidity of Swallows," wherein Dr. 

 Barton was confident he should be able to convince every candid philosopher 

 of the truth of his hypothesis concerning these birds, never issued from the 

 press, although so publicly announced. And who will venture to say that he 

 did not, by this suppression, manifest his discretion ? When Wilson's volume, 

 wherein the swallows are given, appeared, it is probable that the author of the 

 "Fragments" was made sensible that he had been writing upon subjects of 

 which he had little personal knowledge ; and therefore he wisely relinquished 

 the task of instructing philosophers, in these matters, to those more capable 

 than himself of such discussions. 



Naturalists have not been sufficiently precise when they have had occasion 

 to speak of torpidity. They have employed the term to express that torpor or 

 numbness, which is induced by a sudden change from heat to cold, such as is 

 annually experienced in our climate in the month of March, and which fre- 

 quently affects swallows to so great a degree as to render them incapable of 

 flight. From the number of instances on record of these birds having been 

 found in this state, the presumption has been that they were capable of passing 

 into a state of torpidity, similar to that of the Marmots, and other hybernating 

 animals. ^ 



Smellie, though an advocate for migration, yet admits that swallows may 

 become torpid. " That swallows," says he, " in the winter months, have 

 sometimes, though very rarely, been found in a torpid state, is unquestionably 

 true. Mr. Collinson gives the evidence of three gentlemen who were eye-wit- 

 nesses to a number of sand-martins being drawn out of a cliff on the Rhine, 

 in the month of March, 1762." * One should suppose that Smellie was too 

 good a logician to infer that, because swallows had been found in the state de- 

 scribed, they had remained in that state all winter. A little more knowledge 

 of the subject would have taught the three gentlemen observers, that the poor 

 swallows had been driven to their retreat by cold weather, which had surprised 

 them in their vernal migration ; and that this state of numbness, falsely called 

 torpidity, if continued for a few days, would for ever have destroyed them. 



It is now time to resume the subject of Wilson's Ornithology, as the reader 

 will, probably, consider that we have transgressed the limits which our digres- 

 sion required. 



Dr. Drake, in his observations upon the descriptive abilities of the poet 

 Bloomfield, thus expresses himself: " Milton and Thomson have both intro- 

 duced the flight of the sky-lark, the first with his accustomed spirit and 

 sublimity; but probably no poet has surpassed, either in fancy or expression, 

 the following prose narrative of Dr. Goldsmith. ' Nothing,' observes he, 

 ' can be more pleasing than to see the Lark warbling upon the wing; raising 

 its note as it soars, until it seems lost in the immense heights above us ; the 

 note continuing, the bird itself unseen ; to see it then descending with a swell 

 as it comes from the clouds, yet sinking by degrees as it approaches its nest; 

 the spot where all its affections are centred ; the spot that has prompted all 



* Philosophy of Natural History, chap. 20. 



