82 C. BAILLAIEGÉ ON A PAETICULAR CASE OP 



sediment and cause some of it to come oiat, with the effect produced on the wood and 

 iron as related ? or whether the water alone, without any gritty matter and under such 

 pressure, could eat through an inch of iron in less than a year ? 



This wearing away of the iron and wood may also be accounted for in another 

 manner, and the explanation is more rational. The pipe under the river is not only boxed 

 in, as inferred from what has just been stated, but the box is filled in around the pipe 

 with puddled clay. Now this clay may, and probably does, contain a quantity of gritty 

 matter. In like manner, where the pipe was buried in earth, when leakages have from 

 time to time been discovered and repaired, the iron was invariably worn away in the 

 faucet to some extent, as also in the spigot, and this wearing away may be attributed to 

 the attrition or friction caused not only and solely by the water, but by the siiperjacent 

 and adjoining sand falling constantly from above, as the hole in the filling or embank- 

 ment around the pipe increased ; or by the grit being drawn into the eddy of the 

 issuing jet in a way to produce the effect stated. 



The defective pipe was in consecj^uence of this taken out and a new piece inserted ; 

 and, to guard against a similar occurrence a bridge was built over the river, and a new and 

 additional main was laid as a siding to the other. 



This new main forms the siibject of the present paper. It is at an elevation of say, 

 some twenty feet above that imbedded in the river and therefore under a head of 466 

 feet of water or of 200 lbs. to the square inch, and like the other, is of eighteen-inch 

 bore or inside diameter, in twelve feet lengths, with spigot and. faucet joints, five inches 

 deep, run with lead, on gasket bed and staved. It was laid in 18Y3, with a ten-feet rise 

 at the centre of the span, which is 120 feet between the piers. The conduit is supported 

 on cast-iron chairs a foot high, to allow space for repairs to joints and for replacing a 

 broken pipe when recjuired. The object of throwing the pipe up at the centre into a 

 syphon or arch was two-fold : that room might be given for the passage of river crafts 

 beneath it, and that it might be self-sustaining in case of the destruction by fire of the 

 wooden tube which surrounds it on all sides ; this tube being in cross-section, eight feet 

 inside, six feet high, with double walls of three-inch plank, and eighteen inches of saw- 

 dust between the two to guard against the effects of frost. It rests on a flooring of beams 

 supported by the trusses which constitute the framework of the structure. 



For many years past in Quebec, in fact, in the upper wards of the city ever since the 

 laying of the new conduit, owing to the pressure falling off, it has been necessary to 

 have recourse to the intermittent system of siipply. This necessitates the turning on and 

 off of the water every day at certain hoiirs. The stop-gates are all supplied with gearing 

 to prevent their shutting off too rapidly, and creating in consequence what is known as 

 a water-hammer or water-ram. Some years ago, owing to the too rapid working of the 

 gearing of a gate near the summit level in the city, some 300 feet above the level of the 

 conduit in the bridge, one of the twelve-feet pipes, one inch and a quarter thick, and 

 previously tested to stand a pressure equal to that of a column of water, 1,000 feet high 

 or, say, 430 lbs. to the sc[uare inch, burst under the force of the ram due to the cause 

 just mentioned. The pij^e was split along the top through almost its entire length, and 

 the city had to be supplied by the pipe under the river while the other was being 

 repaired. 



This pipe merely rests on the flooring of the tube, as already explained, and is not 



