as machines, are, in
principle, practical necessities, without which nothing can be
unattended with difficulties.

4. All machinery is derived from nature, and is founded on the teaching
and instruction of the revolution of the firmament. Let us but consider
the connected revolutions of the sun, the moon, and the five planets,
without the revolution of which, due to mechanism, we should not have
had the alternation of day and night, nor the ripening of fruits. Thus,
when our ancestors had seen that this was so, they took their models
from nature, and by imitating them were led on by divine facts, until
they perfected the contrivances which are so serviceable in our life.
Some things, with a view to greater convenience, they worked out by
means of machines and their revolutions, others by means of engines, and
so, whatever they found to be useful for investigations, for the arts,
and for established practices, they took care to improve step by step on
scientific principles.

5. Let us take first a necessary invention, such as clothing, and see
how the combination of warp and woof on the loom, which does its work on
the principle of an engine, not only protects the body by covering it,
but also gives it honourable apparel. We should not have had food in
abundance unless yokes and ploughs for oxen, and for all draught
animals, had been invented. If there had been no provision of
windlasses, pressbeams, and levers for presses, we could not have had
the shining oil, nor the fruit of the vine to give us pleasure, and
these things could not be transported on land without the invention of
the mechanism of carts or waggons, nor on the sea without that of ships.

6. The discovery of the method of testing weights by steelyards and
balances saves us from fraud, by introducing honest practices into life.
There are also innumerable ways of employing machinery about which it
seems unnecessary to speak, since they are at hand every day; such as
mills, blacksmiths' bellows, carriages, gigs, turning lathes, and other
things which are habitually used as general conveniences. Hence, we
shall begin by explaining those that rarely come to hand, so that they
may be understood.

CHAPTER II

HOISTING MACHINES

1. First we shall treat of those machines which are of necessity made
ready when temples and public buildings are to be constructed. Two
timbers are provided, strong enough for the weight of the load. They are
fastened tog