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 p538  Fistula

on p538‑539 of

William Smith, D.C.L., LL.D.:

FI′STULA (σωλήν), a water-pipe. Vitruvius (VIII.7 s.6 §1, ed. Schn.) distinguishes three modes of conveying water: by channels of masonry (per canales structiles), by leaden pipes (fistulis plumbeis), and by earthen pipes (tubulis fictilibus); but to these two sorts of pipes the leaden were the more commonly used.1   [Aquaeductus.] They were made by bending up cast plates of lead into a form not perfectly cylindrical, but having a sort of ridge at the junction of the edges of the plate, as represented in the following engraving, taken from antique specimens (Frontin. de Aquaed. p73, fig. 15, 16, ed. Polen.; Hirt, Lehre d. Gebäude, pl. XXXII fig. 8).

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	] 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‑foot length of pipe:

Centenaria from a plate 100 digits wide 1200 lbs.
Octogenaria   80   960  
Quinquagenaria   50   600  
 p539  Quadragenaria   40   480  
Tricenaria   30   360  
Vicenaria   20   240  
Quindena   15   180  
Dena   10   120  
Octona   8   96 2
Quinaria   5   60  

From this scale it is evident, at a mere glance, that the thickness of the plates was 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 (H. N. XXXI.6 s.31) and Palladius (IX.12; cf. the notes of Schneider and Gesner).

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 length of the internal diameters, reckoned 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 1¼ 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, and this system prevailed up to the Centumvicena, which was the largest size in use, as the Quinaria was the smallest; the latter is adopted by Frontinus as the standard measure (modulus) of the whole system. (For further details see Frontinus, de Aquaed. 20‑63, pp70‑112, with the Notes of Polenus.) Another mode of explaining the nomenclature was by the story that when Agrippa undertook the oversight of the aquaeducts, finding the modulus inconveniently small, he enlarged it to five times its diameter, and hence the origin of the fistula quinaria (Frontin. 25, pp80, 81). Of these accounts that of Vitruvius appears at once the most simple and the most correct: indeed it would seem that the plan of measurement was very probably the invention of Vitruvius himself (Frontin. l.c.) Respecting the uses of pipes in the aqueducts, see Aquaeductus.

Of the earthen (terra-cotta) pipes we know very little. Pliny says that they are best when their thickness is two digits (1½ 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. H. N. XXXI.6 s.31; Vitruv. l.c. § 10; Pallad. IX.11). Water pipes were also made of leather (Plin. H. N. V.31 s.34; Vitruv. l.c. § 8); and of wood (Pallad. l.c.), especially of the hollowed trunks of the pine, fir, and alder (Plin. H. N. XVI.42 s.81).

The Author's Notes:

1 The etymological distinction between fistula and tubus seems to be that the former, which originally signified a flute, was a small pipe, the latter a large one; but, in usage, at least so far as water-pipes are concerned, it seems that fistula is applied to a leaden pipe, tubus and tubulus to one of any other material, especially of terra-cotta, as in the above and the following passages (Varro, R. R. I.8; Colum. I.5; Plin. V.31 s.34, XVI.42 s.81, XXXV.12 s.46; Frontinus, see below.)

2 Pliny and Palladius, and even the ancient MSS. of Vitruvius, give here C, which, however, is clearly the error of a transcriber who did not perceive the law of the proportion, but who had a fancy for the round number.

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Page updated: 10 Oct 07