Micrographia: Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries ThereuponHooke, Robert
History
Micrographia: Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries Thereupon
Hooke, Robert
Magnifying glasses -- Early works to 1800; Microscopy -- Early works to 1800; Natural history -- Pre-Linnean works
_Take Lead out of the Pig what quantity you please, melt it down, stir and
clear it with an iron Ladle, gathering together the blackish parts that
swim at top like scum, and when you see the colour of the clear Lead to be
greenish, but no sooner, strew upon it _Auripigmentum_ powdered according
to the quantity of Lead, about as much as will lye upon a half Crown piece
will serve for eighteen or twenty pound weight of some sorts of Lead;
others will require more, or less. After the _Auripigmentum_ is put in,
stir the Lead well, and the _Auripigmentum_ will flame: when the flame is
over, take out some of the Lead in a Ladle having a lip or notch in the
brim for convenient pouring out of the Lead, and being well warmed amongst
the melted Lead, and with a stick make some single drops of Lead trickle
out of the Ladle into water in a Glass, which if they fall to be round and
without tails, there is _Auripigmentum_ enough put in, and the temper of
the heat is right, otherwise put in more. Then lay two bars of Iron (or
some more proper Iron-tool made on purpose) upon a Pail of water, and place
upon them a round Plate of Copper, of the size and figure of an ordinary
large Pewter or Silver Trencher, the hollow whereof is to be about three
inches over, the bottom lower then the brims about half an inch, pierced
with thirty, forty, or more small holes; the smaller the holes are, the
smaller the shot will be; and the brim is to be thicker then the bottom, to
conserve the heat the better._
_The bottom of the Trencher being some four inches distant from the water
in the Pail, lay upon it some burning Coles, to keep the Lead melted upon
it. Then with the hot Ladle take Lead off the Pot where it stands melted,
and pour it softly upon the burning Coles over the bottom of the Trencher,
and it will immediately run through the holes into the water in small round
drops. Thus pour on new Lead still as fast as it runs through the Trencher
till all be done; blowing now and then the Coles with hand-Bellows, when
the Lead in the Trencher cools so as to stop from running._
_Whilst one pours on the Lead, another must, with another Ladle, thrusted
four or five inches under water in the Pail, catch from time to time some
of the shot, as it drops down, to see the size of it, and whether there be
any faults in it. The greatest care is to keep the Lead upon the Trencher
in the right degree of heat; if it be too cool, it will not run through the
Trencher, though it stand melted upon it; and this is to be helped by
blowing the Coals a little, or pouring on new Lead that is hotter: but the
cooler the Lead, the larger the Shot; and the hotter, the smaller; when it
is too hot, the drops will crack and fly; then you must stop pouring on new
Lead, and let it cool; and so long as you observe the right temper of the
heat, the Lead will constantly drop into very round Shot, without so much
as one with a tail in many pounds._
Public-domain text, read in full here on John Shaqi.
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