222 



HEATING AS APPLIED TO HORTICULTURE. 



also, of course, divided. This may be fur- 

 nished with a tap by which to empty it, 

 or at which the gardener may always ob- 

 tain water with the chill taken off. The 

 roof of the hot-air chamber is formed of 

 double slating, with a layer of M'Neil's 

 hair felt, and 2 or 3 inches of sawdust be- 

 tween, and the upper surface is never 

 warm. From these arrangements it is 

 evident that the entire air of the hothouse 

 must flow over the plating through the 

 chamber, and back over the tank of water, 

 (as shown by the direction of the arrows 

 in plan and section,) and be returned back 

 into the hothouse in a heated form through 

 the upper opening. Here it is received 

 into a large brick pit, (as shown by inner 

 lines in plan,) and it is allowed to escape 

 through slate ventilators from the sides 

 and ends of the pit. Iron bars extend 

 across this pit, and on these slates (thick 

 duchesses) are laid : upon these some peb- 

 bles and a few inches of tan as plunging 

 material. Those who have been ac- 

 customed to hot water," Mr Meek says, 

 " may regard the cold-air main drain as 

 the return-pipe, the chamber as an air 

 boiler, the brick pit as a hot-air tank. 

 They can be at no loss to understand 

 either the arrangement or the principle, 

 and to perceive that there is no difficulty 

 whatever in reducing those principles to 

 practice." 



Such was Mr Meek's description of his 

 Polmaise stove, considered to have been 

 the perfection of the principle. Its advan- 

 tages are stated by him to be — economy 

 in erection and maintenance. "Com- 

 pared with hot water," he is assured " that 

 the first cost does not exceed one-half 

 what the cost of the latter would be, to se- 

 cure the same amount of bottom and 

 atmospheric heat in the same house and 

 in the same locality ; that a healthy at- 

 mosphere will be produced by it; an equal 

 distribution of heat secured, entirely inde- 

 pendent of external circumstances; and 

 that constant motion of atmosphere within 

 the house maintained, which is so much 

 wished for by cultivators in general." 



In regard to the economy in the first 

 erection, when compared with hot water, 

 he is perfectly correct ; but then a hot- 

 water apparatus will last for probably a 

 century ; the bars in the grate will burn 

 out in the one case in about the same 

 time as in the other; a boiler will last 



for twenty years, in which time as many 

 Polmaise plates will be cracked and burnt 

 out as will replace half-a-dozen boilers. 

 The wear and tear of fire-bricks, be they 

 Stourbridge lumps or any other, will be 

 the same in both cases. The hot-water 

 pipes, as we have already stated, will not 

 be worn out in a century. How many 

 cold-air drains, and hot-air drains, and 

 duchess slates for covers will be broken 

 or worn out in the same space of time ? 

 As many, we confidently assert, as will 

 very nearly reverse Mr Meek's hasty 

 calculation. Nor do we take into this 

 calculation the many losses of crops of 

 fruit, or collections of plants, which will 

 fall a sacrifice to the economy of a Pol- 

 maise system of heating. In regard to 

 the expense of maintenance — we mean 

 fuel as well as hot plates and cold drains 

 — a very slight knowledge of the proper- 

 ties and operations of heat must lead to 

 the fullest conviction that double the 

 amount of fuel requisite to heat a given 

 space by a well-appointed hot-water appa- 

 ratus, will not heat the same space if 

 burnt under the most perfect Polmaise ap- 

 paratus that has hitherto been constructed. 

 Thus much for the economy of the prin- 

 ciple, without taking into calculation the 

 sleepless nights of the unfortunate wight 

 who has to watch the hot and cold drains 

 and cracked plates of a Polmaise stove, 

 when the thermometer is. travelling to- 

 wards zero. It is rather singular that 

 Mr Meek should enumerate, amongst the 

 catalogue of previous errors in heating, 

 that of placing the " stove in a separate 

 building," and yet have fallen into the 

 same error himself, as will be seen by the 

 plan of his stove previously given. We 

 think it scarcely possible for Mr Meek, 

 or any one else, to heat a house of the 

 same size for less money than has been 

 done by both Mr Toy and D. T. F., as 

 shown in their respective plans given in 

 this work. As for the healthy atmosphere 

 to be produced by this mode of heating, 

 there is something anomalous in the very 

 idea. Air is first passed over very highly 

 heated metallic plates — this rendering it 

 not only unfit for, but actually fatal to, 

 vegetable life ; and when, by this means, 

 its utility has been destroyed, the attempt 

 is made to restore it, to a certain extent, 

 by causing it to pass over a cistern of 

 water. Mr Meek says, in a foot-note, 



