28 FORM AND PECULIARITIES 
One of the peculiarities of the sperm whale, which strikes 
at first sight every beholder, is the apparently dispropor- 
tionate and unwieldy bulk of the head; but this peculiarity, 
instead of being, as might be supposed, an impediment 
to the freedom of the animahs motion in his native ele- 
ment, is. in fact, on the contrary in some respects very 
conducive to his lightness and agility, if such a term can 
with propriety be applied to such an enormous creature ; 
for a great part of the bulk of the head is made up of a 
large thin membranous case, containing, during life, a 
thin oil of much less specific gravity than water; below 
which again is the junk, which, although heavier than the 
spermaceti, is still lighter than the element in which the 
w T hale moves ; consequently the head taken as a whole, 
is lighter specifically than any other part of the body, 
and will always have a tendency to rise at least so far 
above the surface as to elevate the nostril or “ blow- 
hole" sufficiently for all purposes of respiration, and more 
than this, a very slight effort on the part of the fish would 
only be necessary to raise the whole of the anterior fiat 
surface of the nose out of the water ; in case the animal 
should wish to increase his speed to the utmost, the 
narrow inferior surface, which has been before stated to 
bear some resemblance to the cutwater of a ship, and 
w r hich would in fact answer the same purpose to the 
whale, would be the only part exposed to the pressure of 
the water in front, enabling him thus to pass with the 
greatest celerity and ease through the boundless track of 
his wide domain. 
It is in this shape of the head that the sperm whale 
