"I'll tell you what it is, sir," said he. "You'll hexcuse me sayin' of it, but it's no easy job to get at the true depth of water in a ship's bottom when she's tumblin' about like this here."
"I think I got correct soundings."
"Suppose," he continued, "you drop the rod when she's on her beam ends. Where's the water? Why, the water lies all on one side, and the rod 'll come up pretty near dry."
"I waited until the ship was level."
"Ah, you did, because you knows your work. But it's astonishin' what few persons there are as really does know how to sound the pumps. You'll hexcuse me, sir, but I should like to drop the rod myself."
"Certainly," I replied, "and I hope you'll make it less than I."
In order to render my description clear to readers not acquainted with such details, I may state that in most large ships there is a pipe that leads from the upper deck, alongside the pumps, down to the bottom or within a few inches of the bottom of the vessel. The water in the hold necessarily rises to the height of its own level in this pipe; and in order to gauge the depth of water, a dry rod of iron, usually graduated in feet and inches, is attached to the end of a line and dropped down the tube, and when drawn up the depth of water is ascertained by the height of the water on the rod.
It is not too much to say that no method for determining this essential point in a ship's safety could well be more susceptible of inaccuracy than this.
The immersed rod, on being withdrawn from the tube, wets the sides of the tube; hence, though the rod be dry when it is dropped a second time, it is wetted in its passage down the tube; and as the accuracy of its indication is dependent on its exhibiting the mark of the level of water, it is manifest that if it becomes wetted before reaching the water, the result it shows on being withdrawn must be erroneous.
Secondly, as the boatswain remarked to me, if the well be sounded at any moment when the vessel is inclined at any angle on one side or the other, the water must necessarily roll to the side to which the vessel inclines, by which the height of the water in the well is depressed, so that the rod will not report the true depth.