"This harpoon which is made of brass or iron, or steel, is morticed from a to b for the reception of the withers, in the same manner as the hand-harpoon, and the lockings of the withers are on the same principle; but the springs for opening the withers are attached to the wither (c,) instead of to the mark of the harpoon, as in the former instruments; from the point b to a the instrument is sharp, but the outer edges of the withers are blunt and square, as they occupy only the same breadth as the cutting part of the mouth. To the opening d is attached a rope platted of raw hide, or wire to prevent injury in the firing, and of about a yard in length; with this is connected the usual foreganger and line. The novelty of application in this harpoon consists in its being fired with the part d foremost: in effecting the discharge, a cylindrical cap a, of wood, three inches long and two inches in diameter is fitted on the point of the harpoon, the cap being scooped out for its reception. The harpoon is then thrust, point first, in the state represented by figure 7, into the gun.
"The re-action of the line in the heel of the harpoon inverts it soon after it leaves the muzzle of the gun, and keeps its point foremost in the flight. The harpoon, which is cylindrical at the middle, and nine inches long by two inches in diameter, weighs about 512lbs. Captain Manby thinks it capable of carrying a line direct, or point blank, twenty-five yards, while, in the experiments he made, the common gun-harpoon only went nine yards point blank before it struck the ground with the point, and twenty-nine yards, when elevated 15° or 17°. The advantages of this harpoon, therefore appear, to be, its point
