Page:Micrographia - or some physiological descriptions of minute bodies made by magnifying glasses with observations and inquiries thereupon.djvu/88

Rh This is very manifest by the sealed Thermometers, which I have, by several tryals, at last brought to a great certainty and tenderness: for I have made some with stems above four foot long, in which the expanding Liquor would so far vary, as to be very neer the very top in the heat of Summer, and prety neer the bottom at the coldest time of the Winter. The Stems I use for them are very thick, straight, and even Pipes of Glass, with a very small perforation, and both the head and body I have made on purpose at the Glass-house, of the same metal whereof the Pipes are drawn: these I can easily in the flame of a Lamp, urged with the blast of a pair of Bellows, seal and close together, so as to remain very firm, close and even; by this means I joyn on the body first, and then fill both it and a part of the stem, proportionate to the length of the stem and the warmth of the season I fill it in with the best rectified Spirit of Wine highly ting'd with the lovely colour of Cocheneel, which I deepen the more by pouring some drops of common Spirit of Urine, which must not be too well rectified, because it will be apt to make the Liquor to curdle and stick in the small perforation of the stem. This Liquor I have upon tryal found the most tender of any spirituous Liquor, and those are much more sensibly affected with the variations of heat and cold then other more flegmatick and ponderous Liquors, and as capable of receiving a deep tincture, and keeping it, as any Liquor whatsoever; and (which makes it yet more acceptable) is not subject to be frozen by any cold yet known. When I have thus filled it, I can very easily in the forementioned flame of a Lamp seal and joyn on the head of it.

Then, for graduating the stem, I fix that for the beginning of my division where the surface of the liquor in the stem remains when the ball is placed in common distilled water, that is so cold that it just begins to freeze and shoot into flakes; and that mark I fix at a convenient place of the stem, to make it capable of exhibiting very many degrees of cold, below that which is requisite to freeze water: the rest of my divisions, both above and below this (which I mark with a [0] or nought) I place according to the Degrees of Expansion, or Contraction of the Liquor in proportion to the bulk it had when it indur'd the newly mention'd freezing cold. And this may be very easily and accurately enough done by this following way; Prepare a Cylindrical vessel of very thin plate Brass or Silver, ABCD of the figure Z; the Diameter {{{{nowrap|A B}} of whose cavity let be about two inches, and the depth {{nowrap|B C}} the same; let each end be cover'd with a flat and smooth plate of the same substance, closely soder'd on, and in the midst of the upper cover make a pretty large hole {{nowrap|E F}}, about the bigness of a fifth part of the Diameter of the other; into this fasten very well with cement a straight and even Cylindrical pipe of Glass, {{nowrap|E F G H}}, the Diameter of whose cavity let be exactly one tenth of the Diameter of the greater Cylinder. Let this pipe be mark'd at {{nowrap|G H}} with a Diamant, so that G from E may be distant just two inches, or the same height with that of the cavity of the greater Cylinder, then divide the length {{nowrap|E G}} exactly into 10 parts, so the capacity of the hollow of each of these divisions will be {{fs70|$1⁄1000$}} part of the capacity of the greater {{hws|Cylin|Cylinder}} {{rh| |  |der.}}