HYDEAULIC-RAM OE WATER-HAipiEE. 83 



bound to it or triissed to prevent any lateral motion. It mtist be stated that the pipe 

 thus laid and not tied or loaded down, except by its own weight and that of the Avater 

 within it, was, when the burst occurred as above related, only 140 feet from embanktnent 

 to embankment on either side the river. What has just happened and I am now about 

 to relate, might have happened at the time the pipe burst in the bridge, had the unloaded 

 portion of the condviit been of greater extent. It was at that time, as just stated, but 140 

 feet ; all beyond that, on both sides of the river, being imbedded and weighed down by 

 some six to seA'en feet of earth embankment. 



We are now engaged in putting in a new thirty-inch main, side by side, and at five- 

 feet centres from the old eighteen-inch main, which is to extend the whole distance from 

 the fountain head to Quebec, to increase the siipply. Having had a lawsuit, on accou.nt 

 of the pretended obstruction to river navigation by the first (or present) bridge's being 

 built over it to carry the eighteen-inch main, it was not considered prudent to erect a 

 similar structure side by side with the former, and I determined to recommend that the 

 new iron tubular bridge to i-ontain both pipes should be erected on the very site of 

 the present structure and this, of course, without in any way interfering with the present 

 supply through the eighteen-inch main. 



To effect this it was, of course, necessary, as well as being in other respects advan- 

 tageous, as giving the hitherto confined stream greater water-way at this point, to erect the 

 piers or abutments of the proposed new bridge in the rear (or land-ward) of the old piers, 

 thus of course increasing the span by so much. Now to do this, some forty feet of the 

 embankment at each end of the present conduit had to be removed, to make room for the 

 new piers, and the unburied, and therefore unloaded, portion of the main was thereby 

 increased from 140 feet to be about 220 feet. 



Just now the pressure in the pipes, due to the sjiriug freshets, is at its maximum or 

 nearly so, though the qiiantity of water passing into the city is but slightly affected by the 

 variation in the head at Lorette over the centre of pressure of the conduit. The intermit- 

 tent system continues, the pipe passing over the summit level in the city and thence 

 downward to the high levels to be supplied, while for the lower districts it is drawn 

 from a point some eighty feet below the summit level ; and this pipe is every night 

 shut off from the iutra-mural city at T P.M., to increase the pressure on the summit 

 levels. 



On the 18th of April last, just about this hour, it was found that the city was withoiit 

 water. Upon proceeding with men and implements to visit the line of acjueduct some 

 nine miles or less in extent between the fountain head and city, it was discovered that the 

 leakage had again occurred within the bridge, but the water-ram had this time exerted and 

 manifested itself in cjuite another manner, — and this may give some clue to the projection 

 of boilers from their moorings, and to the varying distances to which these are carried on the 

 occasion of their bursting under steam-pressvire. This accident to the Quebec aqueduct 

 might possibly happen elsewhere under like circumstances ; and it is to enable engineers 

 to guard against an occurrence which, in certain situations, might be frai\ght with danger 

 to life and limb and give rise to heavy damages, and also, as already stated, on account of 

 its scientific bearings on practical hydraulics, that I consider it important that the occur- 

 rence should be made known to the scientific and professional world. 



The water was, of course, shut oft' from the bridge, or over-head conduit, and allowed 



