248 



HEATING AS APPLIED IN HORTICULTURE. 



bolts, as will be seen by a glance at our 

 diagram. 



" The allowance made for the expan- 

 sion in cast-iron pipes is, in practice, 

 l-8th inch in 10 feet, or l-960th of their 

 length. When heated from 32° to 212°, 

 cast-iron expands 1 -900th of its length, 

 bar iron 1-819, copper 1-581, brass 

 1-535, tin 1-462, lead 1-351, zinc 

 1-933." — Bernan, in Hist, of Heat- 

 ing, &c. 



M'lntosh's (of Glasgow) patent elastic 

 washer may be used with much advan- 

 tage for packing hot-water pipes ; it is 

 about a quarter of an inch thick, is much 

 cleaner than ordinary plugging, and 

 forms a much more certain and durable 

 joint. 



Most excellent and minute directions 

 are given in " Buchanan on the Economy 

 of Fuel," for the various modes of con- 

 necting cast-iron pipes — a work which 

 should be consulted by all who are inte- 

 rested in the subject. 



" Care must be taken, in joining cast- 

 iron pipes, to allow room for expansion. 

 This is sometimes done in the thimble- 

 joint, fig 330, in which the adjoining 

 ends of the pipes a b are turned true 

 on the outside, and have a thimble, or 

 short cylinder of wrought iron, to enclose 

 them, leaving only a small place for the 

 current. A piece of tin, c, or inner 

 thimble, is interposed, and made to fit 

 well to the turned parts of the pipes, 

 which, under the influence of heat or 

 cold, work forwards or backwards, like 

 a piston in a cylinder. A similar expan- 

 sion-joint, applied to spigot-and-faucet 

 connection, fig. 326, answers very well. 

 Lead cannot be substituted for tin or 

 iron cements in joints, for, by frequent 

 heating, it becomes permanently expand- 

 ed; while the iron pipes, always contract- 

 ing in cooling, and the lead not partici- 

 pating in the contraction, the joints soon 

 get loose. Count Rumford introduced 

 an expansion-drum, b in fig. 329, of thin 

 copper, between the extremities of two 

 pipes, a i, which, in elongating, pressed 

 the sides of the drum inwards, and, in 

 cooling, drew them outwards. The pipes 

 should not be connected with any part 

 of the building, but be quite independent 

 thereof: all the horizontal branches 

 should be supported on rollers, and 

 nothing done to interfere with the expan- 



sion of the different parts." — Tomlinson, 

 on Warming and Ventilating. 



However excellent these internal pro- 

 visions may be for making a secure 

 joint, and they are no doubt well 

 fitted for steam-pipes — for those in 

 which hot water is to circulate — the 

 impediment caused in the circulation 

 by the obstruction must have its objec- 

 tions. Lead has, no doubt, the fault 

 imputed to it above ; but when used 

 in the case of pipes having a bead cast 

 on the end of the spigot, we think it one 

 of the best materials for joinings, as, 

 when it contracts, it leaves the beaded 

 part of the spigot, and thus forms an 

 internal cavity, in which the spigot end 

 of the pipe works backwards and for- 

 wards, as it becomes heated or cooled — 

 providing, by this property of contrac- 

 tion, a joint such as the art of man could 

 scarcely, if ever, imitate. 



Perkins's improved hot-water pipes— 

 of which we have lately seen some excel- 

 lent examples in the new Commercial 

 Bank, Edinburgh — are fitted together 

 with screw-joints and couplings of a 

 peculiar kind, which renders stuffing 

 and cement wholly unnecessary. To 

 this we may add, that these pipes may 

 be taken to pieces, for the purpose of 

 cleaning or removal, with very little 

 trouble— a circumstance which is not the 

 case with others, and which, it must 

 be admitted, is a serious deficiency. 

 The joints to which we have alluded are 

 also more elegant in appearance. For 

 a detail of the principle, vide " Repertory 

 of Patent Inventions, 1841," p. 216. 



The heat given out by hot-water pipes 

 is just as dry as that from smoke flues : 

 it has the advantage, however, of being 

 much purer, and free from the smoke or 

 deleterious gases which accompany flues, 

 unless they are built with great care, 

 and kept in good order. . To obviate 

 this, or rather to supply the air in the 

 house with an amount of humidity equal 

 to that it has been robbed of by the heat 

 from the pipes, various contrivances — 

 some of which we have already noticed— 

 have been recommended. The most 

 sensible of these is that proposed by 

 Mr Ainger, in his valuable essays on 

 " The Production, Distribution, and Pre- 

 servation of Heat," published in " The 

 Gardeners' Chronicle." After alluding to 



