MECHANICS AND USEFUL ARTS. 67 



hole to hole. It is then opened out, and between rollers a perfect tyre is made, 

 without a weld. They have a tyre on exhibition at the works, which, after 

 running 30,000 miles, presents scarcely any appearance of wear on its surface. 



IMPROVED TUYRE FOR SMITHS' HEARTHS. 



The following improvements in the construction of tuyres for smiths' fur- 

 naces, has been made by John Fernie of England. Mr. F., having observed 

 the defects in the common water tuyeres, which in large fires were sometimes 

 burned out in a day, found that, from the smallness of the water-space, steam 

 was formed at the end, which drove the water back into the cistern, and it 

 struck him, as an improvement, to make the space sufficiently large to allow 

 a free circulation of the fluid, and thus prevent the formation of steam. The 

 entire annular space round the nozzle of the blast-pipe, instead of being sup- 

 plied with water from a tube only, is placed hi communication with a large 

 body of fluid by opening direct into the water cistern, which insures in all cases 

 a good supply of water, and as that portion nearest the fire gets hot, it circu- 

 lates, and prevents the metal getting too high a temperature. The first one 

 on this principle was put to work hi 1846, and proved eminently successful; 

 it was a single casting, with the inner pipe for the blast, carried straight 

 through to the back of the water reservoir. A modification was suggested, in 

 which the tuyere was cast in two pieces the one nearest the heat being fixed 

 on a conical joint with bolts and nuts, which can thus be removed when 

 burned out, and a new one supplied. 



IIMPROVEMEXTS IN HEATING APPARATUS. 



General Dembinski, of Paris, has recently patented some novel and ingenious 

 arrangements for obtaining heat, to be applied to heating or warming rooms 

 and large buildings, hot-houses, and to cooking and other purposes. The 

 general principle adopted by the patentee, is such an arrangement of fluted or 

 plain tubes, with tufts of wire passing through them, to be heated in any 

 convenient manner, as, while hot, can have water continually to flow over or 

 through them. The heated surface being extensive, in proportion to the 

 water to be heated, keeps the latter in a constant state of ebullition, and by 

 passing in that state through other pipes, so as to recirculate over the heated 

 surface, great economy of fuel is estimated by the patentee to be the result. 

 A large square or circular flattened vessel is connected with a smaller one by 

 a tube of small diameter at their upper part, and by one of large caliber be- 

 low ; the steam and water, in a state of ebullition, pass along the upper pipe, 

 and the water through the larger tube below, keeping up a constant circula- 

 tion. In such case a single gas-burner only is employed, and the heated pro- 

 ducts of combustion so confined by a tube, as to heat the whole apparatus. 

 There are various modifications of the arrangement, by which a whole suite 

 of apartments can be heated with great facility. Ornamental vases, pillars, 

 plinth?, and other architectural and fanciful designs, may be made the heating 

 medium in halls, staircases, single apartments, etc. 



