VISION. 227 



We have not a doubt it is by the eye alone that 

 the carrier pigeon (Columba tabellaria, RAY) per- 

 forms those extraordinary aerial journeys which 

 have from the earliest ages excited astonishment. 

 We have frequently witnessed the experiment made 

 with other pigeons , of taking them to a distance from 

 the dovecot, expressly to observe their manner of 

 finding their way back, and we feel satisfied that 

 their proceedings are uniformly the same. On be- 

 ing let go from the bag in which they have been 

 carried, in order to conceal from their notice the ob- 

 jects on the road, they dart off on an irregular 

 excursion, as if it were more to ascertain the 

 reality of their freedom than to make an effort to 

 return. When they find themselves at full liberty, 

 they direct their flight in circles round the spot 

 whence they have been liberated, not only increas- 

 ing the diameter of the circle at every round, but 

 rising at the same time gradually higher. This is 

 continued as long as the eye can discern the birds, 

 and hence we conclude that it is also continued 

 after we lose sight of them, a constantly increasing 

 circle being made till they ascertain some known 

 object enabling them to shape a direct course. 



It is not a little interesting to contrast the pro- 

 ceedings just described with those of a pigeon let 

 off from a balloon elevated above the clouds. In- 

 stead of rising in circles like the former, the balloon 

 pigeon drops perpendicularly down like a plummet, 

 till it is able to recognise some indications of the 

 earth below, when it begins to wheel round in a de- 

 scending spiral, increasing in diameter for the evi- 

 dent purpose of surveying its locality, and discover- 

 ing some object previously known by which to direct 

 its flight. 



The rapidity with which the carrier pigeon per- 

 forms long journeys may, perhaps, be adduced as 

 an objection to this explanation. M. Antoine, for 

 example, tells us that a gentleman of Cologne, hav- 



