PERKIN^S BOILER. 



45 



From the end of the top course of pipes the water ascends into tubes 

 arranged for its conduction through the house, and the same water, when 

 it] has given out its heat in the course of its journey, re-enters the coil 

 again by the lowest tier of pipes, and is in its turn heated to arise again, 

 and so on in regular order. In order to guard against the pipes exploding, 

 which they would be apt to do if filled quite full of water, on account of the 

 expansion to which it is hable when heated, and the tubes being securely 

 closed at the ends, the precaution is taken to fiU them only to a certain extent, 

 and also by the use of an expansion tube, which allows of the expansion of 

 the water in the way of high pressure steam. It would appear that this is the 

 most powerfid of aU modes of heating by means of hot water, and that it 

 may be applied to heat structures of a capacity which no other medium, 

 steam only excepted, could accompUsh. The smaUness of the pipes admits 

 of theii" being introduced into situations where the larger pipes of other 

 engineers could not conyeniently be admitted, and as the velocity with 

 which the water travels is so great, it may be carried to almost the same 

 distance as steam. 



Apprehensions are entertained that the pipes used in this mode are habie 

 to biurst from a variety of causes, but ^Ir. Perkins asserts that aU his 

 tubes are now proved prior to beiug used, and capable of bearing three 

 thousand pounds to the square inch, which appears sufficient allowance 

 for extraordinary pressure, when we reflect that sixty pounds or seventy 

 pounds is only necessary to be the resisting power when three hundred 

 degrees of heat is required. 



A variety of other methods of heating by hot water have been pubhshed, 

 but as there are none of them so effectual for general piu^oses as those above 

 alluded to, we wiU now proceed to consider the merits of one or two 

 modes adapted for particular circumstances. 



Busby's method of circulating water by the aid of machinery- is described 

 in Repertory of Patent Inventions, Vol. IY.,p. 137, its principal difference 

 from aU others being in its capabihty of circulating water by means of 

 an apparatus which may be compared to the wheel of a winnowing machine, 

 this is fixed within the boiler to a perpendicular axis, which must be 

 placed exactly over the end of a pipe which reaches from the circiunference 

 to the centre of the boiler. There is also a second pipe which reaches no 

 farther than the circumference. These pipes are united at the end farthest 

 from the fire, and may be made to descend or be carried to any distance and 

 in any form. The boiler and pipes being filled ^ith water, the circidation 

 commences in consequence of a rotatory motion being commimicated to 

 it by the fan or circulator, wliich is made to revolve by the action of the 



