The materials which will be wanted are these:—a glass phial,—one that is broad at the base in proportion to its height, so as to stand firm, is desirable,—a glass tube of small bore, six or eight inches long,—a cork to fit the mouth of the phial,—a little sealing-wax, a lamp, and a small pitcher of water. The work may be safely done upon the parlour-table, provided that the materials are all placed upon a large tea-tray, with an old newspaper, or a sheet of wrapping-paper spread over it. The paper will then intercept any drops of hot sealing-wax which may chance to fall, and which might otherwise injure the tray, and the tray itself will receive whatever may be spilt.
The only article of the above materials in regard to which the reader will have any difficulty, is the tube. Such a tube, however, can usually be procured at an apothecary’s, at a very trifling expense. One about the dimensions of a pipe-stem will be best. In constructing the instrument, this tube is to be passed down through the cord, which is to be placed in the neck of the phial, the lower end to go below the surface of a little water, which is to be put in the bottom of the phial.
The appearance of the instrument, when completed and fitted with a scale, as will be explained hereafter, is represented in the annexed wood-cut. In constructing the instrument, the operations, or the manipulations, as the philosophers call them, are,
First, to bore a hole through the cork, to receive the tube.
Second, to cement the tube into the cork.
Third, to cement the cork into the phial.
1. The first thing is to bore a hole through the cork, and this must be just large enough to admit the glass tube.—After turning in the gimlet a little way, it should be drawn out straight, by which means the chips will be drawn out, and then it should be put in again. For a gimlet will not clear its own way in cork, as it will in wood. By drawing it out, however, in the manner above described, taking care to operate gently, so as not to split the cork, and to guide the gimlet straight through the centre of the cork, the hole may be bored without much difficulty. If the hole is not quite large enough, it may be widened by a penknife which has a narrow blade, or it may be burnt out to a proper size with a hot knitting-needle, or a piece of iron wire. And thus the hole is bored through the cork.
2. The next thing is to cement the tube to the cork. In order to do this, the water is first to be poured into the phial. About one quarter or one fifth as much as the phial will contain, will be sufficient. When this is done, the neck of the phial inside should be wiped dry, for the cork is to be sealed into it, and unless the glass is dry, the sealing-wax will not adhere. Then the tube is to be passed through the cork, and the cork put into its place, and the tube slipped down until the lower end reaches below the surface of the water, and nearly touches the bottom of the phial. Observe, then, at what part of the tube the cork comes, for this part is to be heated, and covered with sealing-wax, in order to seal it into the cork. It may be marked with a touch of ink from a pen, at a point just above where it issues from the cork. Then take out the cork with the tube from the phial, and slip the cork along down towards the lower end of the tube, so that you can put the wax upon the glass.