From the foregoing observation an inference may be drawn, that the incrustation on the internal surface of iron pipes will, in the course of fifty years, so contract the orifices, that it will be absolutely necessary for the pipes to be taken up, cleaned and relaid, during which process some of them may be injured. It had long been discovered, in the instance of the pipe which supplies the Reservoir in Kensington Gardens from the Chelsea water works main, that great difficulty had arisen in making the service, and the cause was unknown until the pipe was examined, so that the incrustation had, it must be presumed, originated some years before that period. It is necessary to observe, that by the progressive incrustation and consequent contraction of the orifices of the pipes, the friction of the water passing through them will be increased, and either a greater power or longer time will be required to force the same quantity of water through iron pipes at the end of fifty years, than was originally allowed. Upon this computation it may be stated, that the progressive requisite increase of power or of time, will occasion a corresponding increase of expense, which in the fiftieth year may amount to fifty per cent. more than was found sufficient in the first year. It is also necessary to observe, that this process of incrustation in iron pipes is calculated upon a supposition that the River Thames water only is used in the pipes. (Signed) THOMAS SIMPSON, Inspector General to Chelsea Water Works. February 24th, 1821. Q. Thomas Simpson, Esq., continued. You were the inventor of the spigot and fosset joint? A. I was. How long ago did you lay them down? I tried some experiments six or seven and thirty years ago, and then I laid a long main for Chelsea water works. And you have never found them want repair? Those that were laid down for the Chelsea water works were taken up and relaid after twenty-seven years, but the first that I laid down, had been laid down six or seven and thirty years, and I never knew them fail yet. Was this experiment on a large scale? No; the first I tried was with some joints we could not make stand in any other way; and we run them in lead and it has not failed. Is it upon a large scale? No, it was one joint I tried. You still use the oakum behind the lead? Yes. You tried one joint at first? Yes; it answered for seven years and never leaked; and then I ventured on laying a main, perhaps 1,500 or 1,600 yards, for the Chelsea water works. How long ago was that? They had been down twenty-seven years; they were taken up two years ago, and relaid in Pall Mall. This main was down about twenty-seven years? Yes; about 1,500 yards long. New joints were put to them when they were relaid ? They were relaid in Pall Mall, then they were joined in the same manner with lead. When you took them up you found no defects in the joints? None whatever. And they had been down twenty-seven years? Yes. Your experiment of thirty-seven years does not go beyond one joint? Two or three joints, perhaps, I tried the experiment on. William Anderson, Esq., Engineer to Grand Junction Company. Q. You have spoken of the decay of a particular pipe which had begun to oxydate or rust; was it owing to its being in calcareous or siliceous earth? A. No, I think not; but it was the inside of the pipe that oxydated. It is probable that iron pipes might not decay in argillaceous earth; have you ascertained how it will be in calcareous earth? No, I have not; it is more from the interior of the pipe that we expect decay. Have you had many instances of the bursting of a pipe? We have had a few. That is an accident which occasionally happens to iron pipes? Yes; but it is occasioned by frost when it does take place, from the contraction. In point of fact, have you had many pipes burst? We have had a few. (Note by Commissioners.) The expense of relaying, will not probably exceed 20 per cent. on the whole first cost of the pipes, laid, and as this will not require to be done, according to the above evidence, under at least 40 years, it is too inconsiderable to form any serious objection to iron pipes. The President and Directors of the Middlesex Canal have considered your communication, dated August 22d, in which this question is proposed: "What sum of money will be taken by the proprietors of the Canal, as a compensation for all damage they may sustain from the Water of Long Pond being diverted from its present course?" This pond is the main source of Concord River; the river is the source of the canal throughout its length. The total diversion of the water of the pond would probably deprive the canal of nearly all its water. A partial diversion would sometimes produce nearly the same effect, that is, in dry seasons, when there is not a drop to spare, if the canal be kept in use. One of your number is, perhaps, better informed than this board is, on this subject. As the inquiry goes to the full extent of the whole value of the canal, in some views, it would be exceedingly difficult to state a sum as a compensation. It wonld be, first, necessary to know precisely, what quantity of water your proposed object would divert; and then to know what effect that diversion might have on the canal's interest. Acting only representatively, this board cannot speak with any authority as to the views of the proprietors, this subject not being within the commonly delegated powers. But speaking individually, the members beg leave to say, that anything within their power, tending to accomplish the valuable purpose of your commission, would be most willingly undertaken by them. Most respectfully, gentlemen, Your obedient servant, PETER O. THACHER, President of the Corporation of Middlesex Canal. 11 ESTIMATES MARKED J. Cost of supply from Long Pond. Acqueduct from Long Pond to Corey's Hill in Brookline. Acqueduct of brick, as shown fig. 1 on plan, Iron pipe across Charles River and Brighton valleys. Open Canal next Pond, 2000 feet 18,518 cu bic yards, a 20 cts., Earth work in the 25 sections, exclusive of mud cutting for base of embankments, all the embankments and excavation for pipes as follows. Price. Earth cutting, at 10 cts. Cubic Yards. Cost. 149 30 $3,703 60 1,493 Mud cutting for base of Embankments, the Embankments and excavations for pipes, as follows, Mud cutting, &c. at 15 cts. 56,013 8,401 95 Form, cylindrical, thickness 8 inches, interior diameter, 4.60 feet-14.44 ft. circumference on inside mean circumference 16.54 27,250 -- bricks to 100 feet lineal. Open area of cross section 16 feet. Bricks delivered at Worcester rail 400 00 19,274 10 Brick Work. Whole cost per 1,000 bricks, 7 90 $3 33 15 22 3 70 $20 60 Equal to -$561 36 per 100 feet, which multiplied by 52.8-$29,640 per mile, 15 miles and 1,600 feet, 2 sections of pipe across the valleys, 30 inch diameter, 2,470 feet= (including slopes and laps) 2,692 feet, at 11 30 per foot, Lead for 299 joints, at 127 lbs. each=37,973 lbs. lead at 63 cts. Laying and leading 299 joints at $2,00= Guard Gates and Strainer, Bridge over Charles river, $30,433 00 2,468 24 598 00 $183,319 86 $453,581 00 33,499 24 1,200 00 11,108 00 15 Ventilating Pipes, at $20, Whole cost of Brick Aqueduct from Long Pond If built of stone as shown at fig. 2 on plan. Open Canal next pond, 2,000 feet, 18,518 cubic yards, at 20 cents, Amount carried forward, 3,703 60 $3,703 60 |