First you must prepare two glasses, the fashion whereof let be like unto the figures marked with the letters A, B, and C, D. The glasse C, D, is open at both the ends, also in the middle there is a neck comming up of sufficient widenesse to receiue the shank end of the glasse marked with the letters A, B. Then fill the glasse C, D, a third part, with either of the waters, and diuide the glasse into so many equall parts as you would haue degrees; rarifie the ayre in the head of the glasse A, B, by holding it to the fire, which being yet warme, reuerse the shank of it into the neck of the glasse C, D. Note that if the water do not ascend high enough, you must take the glasse A, B, out againe, and heat it hotter; if it ascend too high, heat it not so hot. If it be in the dog-dayes, and extreme heat of summer, 1 and 2 are good degrees; if the weather be most temperate, then 3 and 4 are best; if a frost, 9 or 10. When you haue hit an indifferent degree, lute the joynts very close, and fasten a ribben unto the top of the glasse to hang it by. In this glasse the water will with cold ascend the glasse A, B, with heat it will descend the glasse A, B, and ascend the hornes of the glasse C, D. [Illustration] _How to make the single perpendicular glasse, whose water ascendeth with cold, and descendeth with heat._ 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. [Illustration] _The powder for the rock._