THE ENTOMOLOGIST. 57 
islands, we have become impressed with the fact that the 
largest flights of birds occur there during the period of great 
atmospheric disturbance. From the latter end of September 
to that of October, violent revolving gales are prevalent 
throughout the region which comprises the east coast of the 
Southern and Middle* States and the North Atlantic in those 
latitudes, for some 600 or 800 miles from land. At this par- 
ticular period vast flights of birds of all kinds are proceeding 
southward along the coast for their winter resorts in Florida, 
West Indies and South America, and must often meet with 
the violent gales we have alluded to. Now the observations 
of scientific aéronauts, like Glaisher and others, teach us 
that the upper atmosphere is composed of currents of air 
differing in their courses as elevation proceeds, and some 
cases are on record in which balloons at a great height have 
suddenly come in contact with violent direct gales, which 
carried them onward with such velocity as to render their 
course one of extreme peril, only escaping destruction by 
the superior manceuvring of those in charge. Let us suppose 
a violent revolving gale passing along the coast of the 
Southern States, about the latitude of the Bermudas, during 
the period of the autumnal migration of birds and butterflies, 
engulfing some of those great flights which are then proceed- 
ing along in a southerly direction. Drawing them up high 
in its vortex, a direct westerly gale is met with, blowing with 
great force out to sea. Hurled with amazing rapidity along 
this cool aérial current, in the course of about three or four 
hours the heated vapour arising from the Gulf Stream would 
be met with; and would it be considered as too imaginative 
to grant that the ascending warmth of that stream has power 
sufficient to ameliorate the condition of the cool current, to 
stay its rapid course and allow the animal freight to descend, 
which, then within a comparatively short distance of the 
Bermudas, would seek the nearest land by that instinctive 
impulse so characteristic of these tribes, and aided perhaps 
by perfect calm or favouring breeze, arrive at those distant 
isles, without encountering the dangers which—in the form 
of contrary winds—would most certainly accompany an 
* Terias Lisa occurs along the Atlantic Coast from New Hampshire to 
Cuba. It is excessively rare north of Cape Cod, common from New Jersey to 
Cape Hatteras, and extremely abundant farther south.—S. H. S. 
I 
