550 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



engine, and the paddle wheels rose out of the water, there would of course 

 be a great increase of speed, which would suddenly close the throttle valve; 

 but in this apparatus it would open just as sudden. If the valve could be 

 kept closed until the wheels had again entered the water, there would be 

 an advantage in its use, as it appears to act very suddenly. This improve- 

 ment I have no doubt can be made. 



The Chairman. — The Watt governor, so called, was not invented by Watt, 

 but was in use long before the steam engine was known, for the purpose of. 

 regulating the speed of water wheels. 



Water Pipes. 



Mr. Benjamin Garvey read the following report on the use of various me- 

 tallic pipes, for conveying water, which was accepted: 



The committee appointed by the Polytechnic Association of the American 

 Institute to examine and report upon '.' Various kinds of pipes for convey- 

 ing water," with a view to determining their relative mechanical and eco- 

 nomical advantages, respectfully report: That they have deemed it unne- 

 cessary to report on any pipes but those of iron, lead, tin, and tin-lined 

 lead, as these are the only materials which have been made available to 

 any great extent, for conveying water to and through dwellings. 



1st. They find that iron is the best material for pipes of considerable 

 diameter, combining, as it does, strength, cheaptiess and durability with 

 facility of manufacture and emplojMuent; but that the mode of making 

 joints by couplings or cement is far inferior to soldering for the plumber's 

 use, and that the rigidity of iron pipe which prevents it accommodating 

 itself to the change of form produced in the place where it is employed, 

 (by settlement, swagging of timbers, &c.,) unfits it for plumber's work,' 

 Its liability to rust, by the deposition of hygrometric moisture on the out- 

 side, and the liability of this deposition to drip and give rust stains in ceil- 

 ings and walls, is another serious objection to its i;se in dwellings. Iron 

 pipe is also difficult of repair, requiring generally a whole length to be re- 

 moved for a slight defect in any part. The liability to rust is, however, 

 well counteracted by enamelling, galvanizing or tinning, processes which 

 are applicable to large pipes more especially, and which add considerably 

 to the cost. Iron seems to be the best material for large pipes embedded 

 in the earth, or used in continuous and rigid lengths well supported. 



2d. Lead they find to be the most easily manufactured and worked of 

 any metal yet introduced for conveying water through houses, so that it 

 has come to be the almost universal material employed thr'oughout the 

 world, and has given its name to the mechanical art of conveying water 

 into and through houses. Lead readily accommodates itself to the place 

 where it is employed; joints can be made in lead more readily than in any 

 of the other metals named, and defects in lead pipe are more readily obvi- 

 ated, or breaks repaired, than in pipes of any other metal, and for small 

 pipes, such as are required for plumber's work, no material in use is cheaper 

 or more easily employed. If lead were not injurious to health it would be 

 the best material for water-pipes, and is now the most generally employed 

 material for that purpose. 

 3d, Block tin presented more difficulty to your committee. They have 



