Micrographia - Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries Thereupon by Robert Hooke
page 26 of 465 (05%)
page 26 of 465 (05%)
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Window, on a Table, I place my _Microscope_, and then so place either a
round Globe of Water, or a very deep clear_ plano convex_ Glass (whose convex side is turn'd towards the Window) that there is a great quantity of Rayes collected and thrown upon the Object: Or if the Sun shine, I place a small piece of oyly Paper very near the Object, between that and the light; then with a good large Burning-Glass I so collect and throw the Rayes on the Paper, that there may be a very great quantity of light pass through it to the Object; yet I so proportion that light, that it may not singe or burn the Paper. Instead of which Paper there may be made use of a small piece of Looking-glass plate, one of whose sides is made rough by being rubb'd on a flat Tool with very find sand, this will, if the heat be leisurely cast on it, indure a much greater degree of heat, and consequently very much augment a convenient light. By all which means the light of the Sun, or of a Window, may be so cast on an Object, as to make it twice as light as it would otherwise be without it, and that without any inconvenience of glaring, which the immediate light of the Sun is very apt to create in most Objects; for by this means the light is so equally diffused, that all parts are alike inlightned; but when the immediate light of the Sun falls on it, the reflexions from some few parts are so vivid, that they drown the appearance of all the other, and are themselves also, by reason of the inequality of light, indistinct, and appear only radiant spots. But because the light of the Sun, and also that of a Window, is in a continual variation, and so many Objects cannot be view'd long enough by them to be throughly examin'd; besides that, oftentimes the Weather is so dark and cloudy, that for many dayes together nothing can be view'd: And because also there are many Objects to be met with in the night, which cannot so conveniently be kept perhaps till the day, |
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