258 ON AERONAUTIC SPIDERS. 
levity of the lines of those animals, which are repre- 
sented, by some writers on the subject, to be of less 
specific gravity than atmospheric air*: but that each 
of these hypotheses is unfounded, and in direct oppo- 
sition to facts, will be rendered evident by the fol- 
lowing observations and experiments, from which I 
have endeavoured to elicit a satisfactory solution of 
the difficulty. 
That gossamer, which usually abounds most in the 
months of September and October, is perceived to 
ascend into the atmosphere only in serene, bright 
weather, is, I believe, generally allowed: it is also 
admitted that gossamer in the air is invariably pre- 
ceded by gossamer on the ground. These, as will 
appear in the sequel, are circumstances of much im- 
portance in the present investigation, every method 
of accounting for the ascent of gossamer-webs and 
spiders, however plausible, which does not imply their 
concurrence being necessarily erroneous. 
But to proceed to my own researches. A little 
before noon, on the Ist of October, 1826, which was 
a remarkably calm, sunny day, the thermometer in 
the shade ranging from 55°:5’to 64°, I observed that 
the fields and hedges in the neighbourhood of Man- 
chester were covered over, by the united labours of 
an immense multitude of spiders, with a profusion of 
* For a more detailed statement of the above conjectures, see 
the ‘ Introduction to Entomology,’ by Messrs. Kirby and Spence, 
Letter xxiii. 
