FI´STULA
FI´STULA (
σωλήν), a
water-pipe. Vitruvius (
8.6) distinguishes three
modes of conveying water: by channels of masonry (
per
canales
 |
|
Fistulae. (From Middleton's Rome. ）
|
structiles), by leaden pipes (
fistulis plumbeis), and by earthen pipes (
tubulis fictilibus).
1 Of these two sorts of pipes the leaden were the more commonly used
in distributing the water from aqueducts: though draining-pipes of
earthenware were extensively used, as in modern times, and many examples
have been found. The lead pipes were made by rolling thick plates, in
lengths of ten feet, round a wooden core; the edges were then brought
together and soldered with melted lead. The resulting form was not perfectly
cylindrical, but pear-shaped in section, having a sort of ridge where the
edges of the plate were somewhat roughly joined together. (See fig. D.) The
pipes were made of much thicker lead than is the custom now, as much as 20
lbs. to the square foot in existing specimens (Middleton, p. 460); at points
where there was heavy hydraulic pressure they were strengthened or replaced
by bronze pipes, and the taps and stop-cocks (
epistomia, figs. E, F) were likewise of that metal.
In the manufacture of these pipes, particular attention was paid to the bore
and to the thickness. The accounts of Vitruvius, Frontinus, and other
writers are not in perfect accordance; but it appears, from a comparison of
them, that two different systems of measurement were adopted,--namely,
either by the width of the plate of lead (
lamina or
lamna) before it was bent
into the shape of a pipe, or by the internal diameter or bore (
lumen) of the pipe when formed. The former is the
system adopted by Vitruvius (
l.c. § 4);
according to him, the leaden plates were cast of a length not less than ten
feet, and of a width containing an exact number of
digits (sixteenths of a foot), which number was of course different
for different sized pipes; and then the sizes of the pipes were named from
the number of digits in the width of the plates, as in the following table,
where the numbers on the right hand indicate the number of pounds which
Vitruvius assigns to each ten-feet length of pipe :--
| Centenaria, from a plate |
100 digits
wide: |
1200
lbs. |
| Octogenaria from a plate |
80 digits
wide: |
960
lbs. |
| Quinquagenaria from a plate |
50 digits
wide: |
600
lbs. |
| Quadragenaria from a plate |
40 digits
wide: |
480
lbs. |
| Tricenaria from a plate |
30 digits
wide: |
360
lbs. |
| Vicenaria from a plate |
20 digits
wide: |
240
lbs. |
| Quindena from a plate |
15 digits
wide: |
180
lbs. |
| Dena from a plate |
10 digits
wide: |
120
lbs. |
| Octona from a plate |
8 digits
wide: |
962 lbs. |
| Quinaria from a plate |
5 digits
wide: |
60
lbs. |
If this scale is correct, the thickness of the plates must have been the same
for pipes of all sizes; namely, such that each strip of lead, ten feet long
and one digit wide, weighed twelve pounds. The account of Vitruvius is
followed by Pliny (
Plin. Nat. 31. §
§ 57, 58) and Palladius (9.12).
Frontinus, who enters into the subject much more minutely, objects to the
system of Vitruvius as too indefinite, on account of the variation which is
made in the shape of the pipe in bending up the plate of lead; and he thinks
it more probable that the names were derived from the size of the internal
diameters, reckoned
[p. 1.863]in
quadrantes (the unit being the digit), that is,
in quarters of a digit; so that the
Quinaria had a diameter of five-fourths of a digit,
or 1 1/4 digit, and so on, up to the
Vicenaria,
above which the notation was altered, and the names were no longer taken
from the number of
linear quarters of a digit in the
diameter of the pipe, but from the number of
square quarters of a digit in its area. The usual
limits of size were from the
Quinaria, adopted
by Frontinus as the standard measure (
modulus）
of the whole system, to the
Centenaria. This
writer mentions, however, a size larger than the
centenaria, the
centum
vicenûm; and one smaller than the
quinaria, the
digitus rotundus,
or pipe of exactly a digit in bore ( “Digitus rotundus habet diametri
digitum unum; capit quinariae septuncem semunciam sextulam” ; a
roundabout way of expressing 45/72 or 5/8, Frontin. 100.26
extr.). But the largest pipes now extant exceed 300
quinariae (Middleton, p. 466. For further
details, see Frontinus,
de Aquaed. 24-63, with the notes of
Polenus). Another mode of explaining the nomenclature was by the story that
when Agrippa undertook the oversight of the aqueducts, finding the
modulus inconveniently small, he enlarged it to
five times its diameter, and hence the
origin of the
fistula quinaria (Frontin. 25).
Of these accounts, that of Frontinus is the most generally accepted.
The subject of inscriptions on lead pipes was first noticed by Marini
(
Atti de' Fratelli Arvali, Rome, 1795); but it is much
more fully treated in the magnificent work of the Commendatore Lanciani
(
I Comentarii di Frontino, Rome, 1880). Recent
excavations in Rome have unearthed immense quantities of these inscribed
pipes, many of which have unfortunately been melted down as old lead. From
those which have been preserved, Comm. Lanciani has identified 81 sites of
houses within the walls, 88 in the suburbs, and has gathered much valuable
information as to the distribution of water from the various castella, and
many collateral historical and topographical facts. The earliest existing
inscriptions date from the reign of Augustus, the latest from that of
Valentinian II., A.D. 375-392: nearly all the intervening names are
included. They are most numerous in the reigns of Domitian, Nerva, Trajan,
Severus and Caracalla ; after Decius the number steadily declines. The facts
usually recorded on them are the name of the reigning emperor, sometimes the
consuls of the year, the
Procurator Aquarum,
the plumber who made the pipe, the owner of the house, the name of the
estate, the fact of the water being an imperial concession; and many have
numerals, showing the capacity of the pipe in
quinariae (Middleton, p. 462; who adds a copious selection
illustrating the above points, pp. 463-465). Our specimen (fig. A) bears the inscription STATIONIS PROPRIAE PRIVATAE DOM. N. ALEXANDRI AUG.; indicating the
private water supply of the imperial palace under Alexander Severus.
Another, from the Palatine, has [DOM]VS AUGUSTANAE; while a pipe inscribed IMP. AUG. VESPASIANI . STATIO. VRBANA. AUG.
belonged to the public water-works of the city. Respecting the uses of pipes
in the aqueducts, see
AQUAEDUCTUS p. 154
a.
Of the earthen (terracotta) pipes we know very little. Pliny says that they
are best when their thickness is two digits (1 1/2 inch), and that each pipe
should have its end inserted in the next, and the joints should be cemented;
but that leaden pipes should be used where the water rises. The earthen
pipes were thought more wholesome than the leaden. (
Plin. Nat. 31.57; Vitruv.
l.c. § 10; Pallad. 9.11.) Water pipes were
also made of leather (
Plin. Nat. 5.128;
Vitruv.
l.c. § 8), and of wood (Pallad.
l.c.), especially of the hollowed trunks of the
pine, fir, and alder (
Plin. Nat.
16.224).
[
P.S] [
W.W]
