The Boy Tar

by Mayne Reid

About this there appeared no difficulty, and the result proved there was none; for in less than five minutes after conceiving it, I had carried the design into execution, and the measuring-rod stood inside the barrel, with one end projecting some inches on the outside.

Holding this end carefully in my hand, I caused the other to play about on the opposite side, until I felt convinced that it touched the point that was exactly vis-à-vis with the aperture; and then steadying the stick, I notched it with my knife, on a level with the outer surface of the stave. To calculate from this notch would not be correct, as it would be more than the diameter of the cask—that is, in reference to what it would contain—but I had no intention of doing so. I should make allowance for the thickness of the stave, and that would give me the measurement I wanted.

Having made my mark, I drew forth my measuring-rod, piece by piece, as it had been plunged in. I took care as I did so to notch both the splices, so that I might be able to put them together again in the exact place where they had been while making the measurement. All this attention to such minute particulars was of importance, and I knew it to be so, for the mistake of even a quarter of an inch in the length of my diameter would cause a difference of many gallons in the result. Most certainly, then, was it of consequence that I should be precise in my data.

I now had the diameter of the swell; the next thing was to get that of the head, or end. About this there was less difficulty—in fact, not any. It was obtained in a few seconds.

Though I could not myself get round either of the ends of the butt, nor even my arm, I could pass the rod around them, and in this way measure them. Even had there not been space to admit the measuring-stick, I should have found a means—by simply drilling another hole with my knife, close to either end, and gauging as before. But this would have occupied time, and it was not necessary to do so, since the stick passed along the head of the butt without any obstruction, till its end rested against the projecting rim on the opposite side. I had nothing to do but assure myself that its point was fair in the middle, and then make my mark as before.

The length of the butt was yet to be ascertained; and this, though apparently a simple operation, cost me a good deal of consideration, before I could get at it with any degree of exactness. You may fancy that it would have been easy enough to get at the length, by just placing the stick parallel to the cask, and notching it square with the ends of the latter? And so it might be easy enough, with plenty of light around you to see when it was square, and a level surface upon which to rest your measure. But as I had the advantage neither of light nor level ground, I encountered great difficulty in this operation. I could not tell when the ends lay even with each other, merely by the touch. I had to pass my fingers from one to the other, and could not grasp both at one time—that is, the rim of the cask and the end of the rod—since they must needs be several inches apart. The stick, too, lay unsteady, and by the feel I could not be sure when its end was exactly “flush” with the head of the cask. The mistake of an inch—it might be several—would falsify all my computations, and render them of no use. It would not do to proceed upon such a conjectural basis, and for a while I was puzzled, and had to pause.

This was an unexpected obstacle, for I had from the first regarded the diameters as the only difficulty; about the possibility of obtaining the length, I had never entertained a doubt.

But my wits again came to the rescue, and I soon discovered a plan that would effect the end in view. I had to make another rod—by splicing two more lengths split from the board—and with this I was able to determine the point.

I managed the matter thus: The old rod I pushed along the head of the cask quite beyond its outer edge, so that it rested at both ends against the projecting rim. Thus placed, it was exactly parallel with the plane of the barrel’s head, while a foot or more projected outward and towards me. Holding the end of the second rod against this projecting part, and at right angles, I gave it a direction along the side of the cask, and I was able to mark the point, where the middle part of the swell came in contact with the second rod. This, of course, after deducting the depth of the rim and the presumed thickness of the head, gave me half the length of the interior of the cask, and that was all I wanted, since two halves make one whole.

I was now in possession of the data of my problem; it only remained for me to seek the solution.