34 
THE BONES. 
spawn, worms, or other soft water insects. One other beak 
only shall he mentioned, — namely, that of the Spoonbill, which, 
in its food, partaking of the nature of the Heron and Duck 
tribes, is provided accordingly ; its interior part being fur- 
nished with rough projections which prevent the escape of 
such slippery things as small fish, while its wide spoon- 
shaped end enables it to crush and sift mud and weeds for 
worms or soft vegetable matter. 
The hones of birds, like those of animals, are for the 
most part white, hut in other respects, they differ materially 
from those of four-footed animals, being composed of a thin, 
firm, and partly elastic substance, formed in layers ap- 
parently fastened together, and almost always hollow ; the 
cavities never containing marrow, hut air, and communi- 
cating with the lungs by considerable openings ; whereby 
they are rendered buoyant and light to a much greater 
degree than is generally supposed. Thus a portion of the 
leg of a Goose, about two inches in length, weighed about 
forty grains, while a piece of the leg of a rabbit (the marrow 
having been extracted, and both being perfectly dry, and as 
nearly as possible of the same thickness and length,) weighed 
seventy- five grains, or nearly twice the weight of the 
similarly- sized hone of the goose, and yet so firm and strong 
was this latter, that although in diameter it was less than 
one-eighth of an inch, and the solid tubular part not more 
than one -hundredth part of an inch in thickness, it could not 
he broken asunder by the hand. 
It is upon this principle mechanics and engineers act 
in constructing strong supports, knowing that if any quan- 
tity of material is to he fabricated into a rod of a certain 
length, the rod will he strong in proportion to its thickness ; 
and that if the figure remains the same, that thickness 
can only he increased by making it hollow. Therefore 
hollow rods or tubes of the same length and quantity of 
matter have more strength than solid ones of less dia- 
meter. This is hut one out of the hundreds of instances 
in which the wisdom of man has been perfected by studying 
the mode by which the great Creator accomplishes His 
purposes. 
