The Notebooks of Leonardo Da Vinci

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HOW CASTS OUGHT TO BE POLISHED.

Make a bunch of iron wire as thick as thread, and scrub them with
[this and] water; hold a bowl underneath that it may not make a mud
below.

HOW TO REMOVE THE ROUGH EDGES FROM BRONZE.

Make an iron rod, after the manner of a large chisel, and with this
rub over those seams on the bronze which remain on the casts of the
guns, and which are caused by the joins in the mould; but make the
tool heavy enough, and let the strokes be long and broad.

TO FACILITATE MELTING.

First alloy part of the metal in the crucible, then put it in the
furnace, and this being in a molten state will assist in beginning
to melt the copper.

TO PREVENT THE COPPER COOLING IN THE FURNACE.

When the copper cools in the furnace, be ready, as soon as you
perceive it, to cut it with a long stick while it is still in a
paste; or if it is quite cold cut it as lead is cut with broad and
large chisels.

IF YOU HAVE TO MAKE A LARGE CAST.

If you have to make a cast of a hundred thousand pounds do it with
two furnaces and with 2000 pounds in each, or as much as 3000 pounds
at most.

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