Read it through once

[11] It will be seen in some other place of what a very light substance the entire interior of the sperm whale’s enormous head consists. Though apparently the most massive, it is by far the most buoyant part about him. So that with ease he elevates it in the air, and invariably does so when going at his utmost speed. Besides, such is the breadth of the upper part of the front of his head, and such the tapering cut-water formation of the lower part, that by obliquely elevating his head, he thereby may be said to transform himself from a bluff-bowed sluggish galliot into a sharp-pointed New York pilot-boat.