CLASS II. AVES: ORDER 2. PASSERES. 
89 
tlie numerous individuals of tliis tribe tliat flit before him, fix his eye on a particular one, and fol- 
low, for a while, all its circuitous labyrinths — its extensive sweeps — its sudden, rapidly reiterated 
zigzag excursions, little inferior to the lightning itself — and then attempt, by the powers of math- 
ematics, to calculate the length of the various lines it describes. Alas! even his omnipotent flux- 
ions would avail him little here, and he would soon abandon the task in despair. Yet, that some 
definite conception may be formed of this extent, let us suj)pose that this little bird flies, in his 
usual way, at the rate of one mile in a minute, which, from the many experiments I have made, 
I believe to be within the truth ; and that he is so engaged for ten hours every day ; and further, 
that this active life is extended to ten years — many of our small birds being known to live much 
longer, even in a state of domestication — the amount of all these, allowing three hundred and 
sixty-five days to a year, would give us two million one hundred and ninety thousand miles — up- 
ward of eighty-seven times the circumference of the globe !" 
These birds commonly build in barns, often attaching their nests to the rafters. They are cup- 
shaped, and consist of mud, laid in regular strata, mixed with hay, and lined with feathers. It 
usually requires a week for them to construct one of these, during which period they manifest the 
most industrious activity. The eggs are usually four in number, and there are two broods in a 
season. Two popular errors in regard to this bird have extensively prevailed : one was, that if a 
swallow was killed by any one about the barn, the cows would give bloody milk; another, that 
they buried themselves in deep, miry ground, and lay in a torpid state during the winter. These 
fallacies are now wholly discarded. 
THE BANK-SWALLOW OK SAND-MARTIN. 
The Bank-Swallow or Sand-Martix, H. riparian is common to Eui'ope, Asia, and America ; 
its length is five inches ; the upper parts are grayish-brown ; under parts white. It appears to be 
the most sociable with its kind, and the least intimate with man, of all our swallows, living 
together in large communities of sometimes three or four hundred. On the high, sandy bank of 
a river, quarry, or gravel-pit, at a foot or two from the surface, they commonly scratch out holes 
for their nests, running them in a horizontal direction to the depth of two and sometimes three 
feet. Several of these holes are often within a few inches of each other, and extend in various 
strata along the front of the precipice, sometimes for eighty or one hundred yards. At the ex- 
tremity of this hole a little fine dry grass, with a few large downy feathers, form the bed on 
which their eggs, generally five in number, and pure white, are deposited. The young are hatched 
late in May, and then the common crow, in parties of four or five, may sometimes be seen watch- 
ing at the entrance of these holes, to seize the first straggling young one that should make its ap- 
pearance. From the clouds of swallows that usually play round these breeding-places, they 
remind one at a distance of a swarm of bees. 
Other American species are the Republican or Cliff-Swallow, H. opifex, noted for associa- 
VoL. II.— 12 
