Prepare two glasses after the fashion of these figures underset, F, G, I, I. Alwayes chuse those upper glasses that haue the least heads, else they will draw the water too fast, and presse it too low: also let not the shank of the glasse bee too wide: it is no matter to bee curious in chusing the lower glasse. Hauing prouided both these glasses, make a frame for them about one inch longer than the shank of the glasse F, G, hauing a hole at the top to put the same thorow. There ought to be a great deale of care had in making the frame so, that the foot thereof may bee of a greater compasse than the top, to the end that it may stand firm, and not be subject to be turned down, which will distemper the whole work. After you have provided the frame, proceed to the making of it after this manner. Put both the glasses into the frame, and then divide the shank of the glasse F, G, into so many equall parts as you would haue it haue degrees; write figures upon paper, and paste them on (with gum tragagant dissolued in faire water;) then fill the bottom glasse 2 thirds with the water, and rarifie the ayre in the glasse F, G, so often untill you haue hit such a degree as is most fitting for the temper of the weather, put in a little crooked hollow cane for the ayre to passe in and out at, but let it not touch the water: then stop it about the joynts of the glasse with good cement, that nothing may come out. Make an artificiall rock about it, with peeces of cork dipt in glew, and rowled in this following powder, and it is done.
The powder for the rock.
Take mother of Pearle 2 pound, small red Corall di. pound, Antimony crude 4 ounces, and make a grosse powder of them.
To make the single perpendicular glasse, ascending with heat, and descending with cold.
Prepare two glasses after the fashion of the figure A, B, and C, D: let the glasse A, B, haue a small pinhole at or about the top of all, and let the glasse C, D, haue besides the hole at the top, another hole at the bottom with a short pipe. Prouide such a frame for this as you did before for the other; then put the glasses into it, fasten the bottom glasse to the bottom of the frame, hauing a hole at the bottom, thorow which the pipe of the glasse C, D, may passe, fit a cork unto it: then lute the two glasses together, so that no ayre may passe between the joyning; divide then the shank into so many degrees as you please, and figure it as before I taught you, then with the heat of a candle, rarifie the ayre in the glasse C, D, and fill it a third part full of water, and then put the cork fast in. Note that if the first heating of the glasse rayse not the water unto your content, you must repeat it over and over, untill it doe: when it is sufficient, then stop the cork in very firm, that no water may come out, and it is made.
How to make the double perpendicular glasse.
Prepare two glasses like unto the figure marked with the letters A, B, the one of them must have a small hole in or about the head thereof. Prepare likewise for the bottom a vessell of the fashion of the figure G, H, having two mouthes, at each end one, also a cocke in the middle, as K: divide then the shank of the glasse without the hole in the top, into equall parts, and set figures upon it: next lute them both fast into the necks of the bottom vessell. (But first remember to put them in a frame:) when the cement is dry turn the cock of the bottom vessell, and rarify the ayre in the glasse that hath no hole at the top; then set the bottom vessell a little way into a vessell filled with water, and it will suck up the water as it cooleth, when the bottom vessell is full, also the water mounted in that top glasse without a vent, up to a fitting degree; (the temper of the weather regarded) then depresse (but gently) the glasses into the vessell of water, untill the water be come up into the glasse with the vent at the top sufficiently, that is, so that in both the glasses may bee contained so much water as will fill the shank of one, and about 2 or 3 degrees of the other; then turne the cock, and take away the vessell of water from under them, let them down, and fasten the bottom vessell unto the bottom of the frame, and make a rock about it, or else what other works you please, that the art may not be discerned. Lastly, set figures upon both, but first upon that without the vent, beginning from the bottom, and proceeding upwards, then lay your hand upon the head of it, which will depresse the water, which when it commeth equall to the degrees, paste the same degree on the place of the water in the other glasse with the vent, and it is done.
