MECHANICS AND USEFUL ARTS. 59 



He adopts a peculiar and novel flange-joint, flexible only in a perpen- 

 dicular plane, but so secure as not to need a wooden frame to accom- 

 pany the pipe. The adaptation of this joint to the purpose, and its 

 strength, are quite admirable. The distance between the joints is 31 

 feet 4 inches, and each section consists of three pieces of twenty-inch 

 pipe, one inch and a half thick, and with flanges two inches thick, se- 

 curely bolted together. These three pieces of pipe weigh together 

 3,300 pounds, and each joint weighs 3,800 pounds, the size of the 

 pipe being considerably enlarged at the joint. The opposite sections 

 of the joint meet on a perpendicular plane, parallel with the axes of 

 the portions of pipe on each side of the joint, and move upon a 

 leather packing, which is placed in a groove between the two flanges. 

 One of these flanges is so much wider than the other as to have a cap 

 or ring bolted to it, which incloses and holds the other, and thus con- 

 stitutes the joint. The strength of this arrangement is obvious, and 

 its tightness has been tested by trial, under a pressure of 250 pounds 

 to the inch. The pipe when lowered is to be placed in a trench, 

 which has been dredged in the bottom, and then covered with clay 

 and gravel. About 500 feet of the channel is to be crossed in this 

 way, and for the remainder, which is about 1,100 feet across the flats, 

 the pipe is to be inclosed between rows of piles, so low as to pass be- 

 neath the wharves, when they come to be built. Boston Chronotype. 



APPARATUS FOR PREVENTING THE BURSTING OF WATER-PIPES 



FROM FROST. 



MR. ALEXANDER MACPHERSON, of Leith, read a paper to the Brit- 

 ish Association, on the bursting of water-pipes from frost. After re- 

 ferring to the various plans which have been adopted for preventing 

 this inconvenience, he says that the only really practical means of so 

 doing is to keep the pipe empty, and the means at present of effecting 

 this is to place two cocks on a low part of the supply-pipe, and by 

 the one to shut off the water, and by the other to empty the pipes. 

 But to render this plan of any avail, great watchfulness is necessary ; 

 and the consequence is, that even where the cocks exist, they are rarely 

 used in time. " Reasoning on this," Mr. Macpherson goes on to say, 

 " I have conceived the possibility of employing some self-acting ap- 

 paratus, which, on the approach of a low degree of temperature, would 

 of itself shut off the water and empty the pipe ; or, in other words, of 

 having a machine so constructed and regulated, that it would shut a 

 cock before the freezing-point of water is reached, and open it when 

 the temperature assumed its normal state." This requisite motive- 

 power was first considered attainable by mercury confined in a bul- 

 bous glass vessel, acting as a barometer, with the difference of having 

 a cylinder and piston. The next was suggested to Mr. Macpherson 

 by Sir David Brewster, and consisted of employing the expansion of 

 metallic rods, on the principle of the pyrometer. But his experiments 

 led him to the result, that the freezing of pipes depends on their ca- 

 pacity for conducting heat. Thus, copper, as a conductor, is to lead 

 as five to one ; and therefore a determinate quantity of pure distilled 



