319 SCIENTIFIC NEWS. 



After the pipes are filled one or more openings will be ne-" 

 cessary, to allow a small portion of steam constantly to 

 escape, to keep up the heat of the pipes. If this be not 

 done, air will accumulate, and occupy the place of the 

 steam. It is best to make the condensed water run in the di- 

 rection of the steam, which will driv6 the water before it in a 

 horizontal pipe, or even in one with a considerable acclivity. 

 Great care must be taken however, that no water lodges in 

 the pipes: for, the water remaining in the pipes after they 

 become cool keeps one part of them cold ; the next time the 

 steam is let into the pipes the regular expansion is prevented, 

 some part of the pipe cracks, and a violent explosion takes 

 place, racking the joints to a considerable distance in every 

 direction. The common arrangement is to have a hori- 

 zontal pipe going off separately from each vertical pipe<r 

 Tbis requires an opening for letting out the air at the end 

 of each horizontal pipe. A great improvement is first to 

 carry the steam to the upper story in a vertical pipe, and 

 close under the ceiling in a horizontal one nearly to the op- 

 posite end of the building; thence in a vertical pipe to the 

 story beneath, and again horizontally under the cieling ; 

 and thus from story to story till it corner to the bottom j 

 ■where the condensed water may be allowed to run off by an 

 inverted siphon, which will allow the water to escape, 

 while its pressure confines the steam. The air may be 

 allowed to escape by a stopcock at the same place. 

 Mode of cou- 5. When the joints are formed by bolted flanches, these 

 neaing them, are liable to be broken from inequality of expansion, 

 or to leak at the bolt-holes. Spigot and faucet joints 

 do very well in some cases, but sometimes the faucets burst 

 from the greater expansion of the spigots. If the ends of 

 both pipes be included in thimbles, though these are equally 

 liable to break, the expense is trifling compared with that 

 of a whole pipe. For branch pipes the joinings should be 

 made by saddles and hoops embracing the main pipe. 

 Where there is much silk of unequal expansion, the joints 

 should be secured by a soft stuffing of hemp, or cotton, and 

 tallow ; but in most cases they may be made with iroil ce- 

 ment, composed of ion borings 40lbs, sal ammoniac lib, 

 sulphur |ib, well mixed together and beaten like putty. 



The 



