34 BRITISH BIRDS, WITH THEIR NESTS AND EGGS. 
The House-Martin builds its nest against a wall, and immediately below and 
up to a projecting ledge; rectangular eaves of houses are preferred, but sometimes 
projecting bricks on railway- and other arches are used, or ledges of rock; the 
nest being completely closed in with the exception of a semi-circular or demi-semi- 
circular hole at the top, and usually in the centre. 
The nest is formed of mud without, and with hardly any admixture of grass 
or hair; it is consequently so much more brittle than that of the Swallow, that, 
with the greatest care, using a long sharp table-knife, I never succeeded in obtain- 
ing a perfect specimen; indeed most nests fall into fragments at the first attempt 
to detach them, leaving nothing but the lining with the eggs in the hand held 
below as a support: this lining consists of dry grass, and sometimes, but not 
invariably, a few feathers. The eggs number from four to six; in form they are 
generally elongated ovals, pure white, and immaculate, but appearing rosy when 
fresh-laid; they are smooth and thin shelled, moderately glossy, but not exactly 
shiny. 
When attempting in vain to secure a perfect nest of this species, it has often 
surprised me that the mere weight of the nestlings does not burst the fragile mud 
shell; the glutinous saliva of the bird is supposed to assist in uniting the mud pellets 
in the first instance, but one would expect a driving rain to be more than sufficient 
to counteract that slight advantage: why this species so rarely uses hay and hair to 
strengthen its walls is another puzzle, for the additional stability which it gives 
to a Swallow’s nest is so considerable; that, taking a metal dipper filled with hay 
to the top of a chimney, I have only had to lower the edge of the metal pan 
below the nest and jerk it upwards, to secure the nest uninjured. 
The food of the Martin consists wholly of insects, which it obtains on the 
wing; in confinement, however, it readily feeds upon the usual soft food. In the 
first week of July, 1891, my colleague, Mr. W. R. Ogilvie Grant obtained a nest 
of four House-Martins about a week old, and gave them to me. Following out 
the mistaken notions of many aviculturists I at first fed these young birds partly 
upon raw rump-steak finely minced; but I also gave them a mixture of carefully 
selected ants’ cocoons, and preserved yolk of egg, ground up in a mortar with 
maizena wafers, the whole carefully mixed together, and slightly damped. Upon 
this diet all four attained their full size, after which they refused the raw meat, 
but continued to eat the mixture greedily. 
I kept these birds in a basket filled with hay, and several times each day they 
were taken out and encouraged to fly about the room; but now they began to 
object to return to the close confinement of their ey therefore I purchased a 
large cage, hung up a cocoa-nut nest lined with flannel in one corner, and taught 
