y for use
as water, seeing that any living creature can, if deprived of grain or
fruit or meat or fish, or any one of them, support life by using other
foodstuffs; but without water no animal nor any proper food can be
produced, kept in good condition, or prepared. Consequently we must
take great care and pains in searching for springs and selecting them,
keeping in view the health of mankind.

CHAPTER IV

TESTS OF GOOD WATER

1. Springs should be tested and proved in advance in the following ways.
If they run free and open, inspect and observe the physique of the
people who dwell in the vicinity before beginning to conduct the water,
and if their frames are strong, their complexions fresh, legs sound, and
eyes clear, the springs deserve complete approval. If it is a spring
just dug out, its water is excellent if it can be sprinkled into a
Corinthian vase or into any other sort made of good bronze without
leaving a spot on it. Again, if such water is boiled in a bronze
cauldron, afterwards left for a time, and then poured off without sand
or mud being found at the bottom of the cauldron, that water also will
have proved its excellence.

2. And if green vegetables cook quickly when put into a vessel of such
water and set over a fire, it will be a proof that the water is good and
wholesome. Likewise if the water in the spring is itself limpid and
clear, if there is no growth of moss or reeds where it spreads and
flows, and if its bed is not polluted by filth of any sort but has a
clean appearance, these signs indicate that the water is light and
wholesome in the highest degree.

CHAPTER V

LEVELLING AND LEVELLING INSTRUMENTS

1. I shall now treat of the ways in which water should be conducted to
dwellings and cities. First comes the method of taking the level.
Levelling is done either with dioptrae, or with water levels, or with
the chorobates, but it is done with greater accuracy by means of the
chorobates, because dioptrae and levels are deceptive. The chorobates is
a straightedge about twenty feet long. At the extremities it has legs,
made exactly alike and jointed on perpendicularly to the extremities of
the straightedge, and also crosspieces, fastened by tenons, connecting
the straightedge and the legs. These crosspieces have vertical lines
drawn upon them, and there are plumblines hanging from the straightedge
over each of the lines. When the straightedge is in position, and the
plumblines