Chapter 30 - The Boy Tar by Mayne Reid
My Measuring-Rule
The details of my plan suggested themselves in the following order:—
While examining the cask, to find if there was not some means of ascertaining its different diameters, I discovered the very way itself. All I wanted was a straight rod or stick, of sufficient length to reach quite across the butt at its thickest part. It was plain to me, that by inserting such a stick into a hole in one side of the cask, and passing it on till it touched the staves on the other side, at a point diametrically opposite, I could thus obtain the exact measurement of the diameter of that part of the vessel, since the portion of the rod reaching from side to side would be the diameter itself. The diameter once obtained, it needed only to multiply by three to get the circumference. But in the calculation which I was desirous of making, it was the diameter itself I wanted to find, and not the circumference. I only thought of the latter, because, under ordinary circumstances, when a cask is bunged up, it is easier to measure the circumference of the swell than its diameter. In no case does it signify which, as the figure three will always reduce the one to the other, near enough for most practical purposes, though not mathematically exact.
Now, it so chanced that one of the holes I had cut through the staves had been made in the very middle of the swell, where the butt was thickest. Therefore a straight stick passed into this hole, and pushed on till it touched the opposite side, would give the greatest diameter of the cask.
You may imagine that this might have been obtained by simply planting the stick in a vertical position outside the butt, and notching it at a point on a level with the top of the vessel. True, this might have been done had I been operating with a barrel lying upon a plain surface, with nothing around it to obstruct me, and plenty of light to observe the true level. Even thus it would have been rough guess work, and not to be depended on when a calculation was to be made involving life or death in its consequences—for such it really did involve—at least, I supposed so. But the butt was so placed, resting upon the timbers of the ship, with its swollen side sunk between them, that I could not have measured it in this manner. Even though I might have marked a rod on a line with its top, I could not have planted the other end so as to be on a level with its base.
There seemed no other way to get at the thing than by inserting a straight stick into the hole, and thus measure the diameter; nor did I trouble myself about any other, as this appeared to be the best plan I could adopt.
Where was I to find my stick—my measuring-rule? That is your question, is it not?
It is easily answered. The deal board that had formed part of the biscuit-box would supply me with the material, and out of that I could soon make one. No sooner thought of than I set about it.
The board was but a little over two feet in length, and of course not long enough to reach across the great cask, which at its thickest part appeared four or five. But a very little ingenuity sufficed to overcome this obstacle. I should only have to split off three thin pieces, and by splicing their ends together, I should get a stick of length sufficient.
I did so. Fortunately, the deal was cut nicely with the grain of the wood; and in splitting it, I guided the blade of my knife so as not to let it run out at the edges.
I succeeded in getting three pieces of the thickness I wanted; and, after shaving off their angles, and making them clean and trim, I cut their ends with a slant for the splice.
The next thing was to obtain two pieces of string, and this was the easiest thing in the world. I wore upon my feet a pair of little “buskins” that laced up to the very ankle. The laces were thongs of calfskin, each of them a full yard long. They were just the thing; and, drawing them out of the holes, I completed the splicing, and now held in my hands a straight stick full five feet in length—quite long enough, I conceived, to reach across the thickest part of the butt, and slender enough to go into the hole—which I had already widened a little to receive it.
“So far good,” thought I; “I shall now insert the measuring-stick, and find my diameter.”
I rose to my feet to carry out this design, but I need not describe the mortification I felt on perceiving that the first of these operations, which would appear to be the simplest of all, could not be performed. At the first trial I saw that it was quite impossible. It was not because the hole was too small, or the stick too large. I had made no mistake about this; but my miscalculation was in regard to the space in which I had to work. Lengthways my little chamber was nearly six feet, but crossways little more than two; and up where the hole was—in which I intended to insert the measuring-rod—it was still less. Of course to get the stiff piece of stick into the cask was plainly impossible—without bending it, so that it must break—for the dry deal would have snapped through like the shank of a clay pipe.
I was a good deal chagrined at not having thought of this before; but I was still more vexed at the idea of being obliged to abandon the design of making the measurement I had intended, for before reflecting I believed that this was to be the result. A little further consideration, however, helped to a new plan, proving the importance of not arriving too hastily at conclusions. I discovered a way of getting in the stick to its full length, without either breaking or bending it.
This could be effected by taking it to pieces again, then first inserting one of the pieces, and holding it till the second could be spliced on to its end, and then pushing both into the cask, and joining the third piece in a similar fashion.
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.