REN 



[ 771 ] 



REN 



requires to be kept lighted for two 

 hours at night, and again for the same 

 period in the morning ; the water, when 

 once heated, retaining its temperature 

 for a long time. In a small house, the 

 apparatus can he constructed for 5, 

 and in all, for less than half the cost of 

 hot-water pipes. The saving in tan 

 and lahour is also very great ; in some 

 places tan costs 19s. per cart-load, and 

 where it is cheaper, the trouble and 

 litter incident to its employment, and 

 the dangers of loss from fungi and in- 

 sects, of which it is the peculiarly fer- 

 tile foster-parent, render it objection- 

 able as a source of heat ; and when- 

 ever the tan has to be renewed, the 

 trouble and destruction of plants is 

 always great. 



"In my new propagating house," 

 says Mr. Rendle, " the tank or cistern 

 is placed in the centre, with a walk 

 surrounding it, so as to enable the pro- 

 pagator with greater ease to attend to 

 the plants, c. 



" On the outside of the house is a 

 fire-shed, in which the boiler is fixed. 

 The tank, made of wood, one-and-a- 

 half or two inches thick, which I find 

 the cheapest material (it also prevents 

 the water cooling so fast as it does 

 either in stone or iron), may be lined 

 with lead or zinc. Exactly in the cen- 

 tre of the tank is a partition, serving 

 the double purpose of causing the 

 water to circulate, as well as to sup- 

 port the edges of the slates, an aper- 

 ture being left in the partition, of about 

 two inches in breadth, to allow the 

 water a free passage. The flow-pipe 

 enters near the appendage of the tank, 

 at the mouth of which pipe a piece of 

 perforated copper is placed, as also at 

 the return-pipe, to prevent dirt and 

 sediment from finding its way into the 

 boiler. After everything is properly 

 fixed, the tank is filled with water, 

 which, of course, at the same time fills 



the boiler The tank is about four 



inches deep. Across it, and resting on 

 its sides, are placed slate stones about 

 an inch-and-a-half thick, cut square at 

 the edges. These are fastened to each 

 other by Roman cement, or Aberthaw 

 lime, to prevent a superfluity of steam 

 (torn escaping into the houses, >.. 



Around the edges of the slates a piece 

 of inch-board, about nine inches deep, 

 should be placed to enclose the saw- 

 dust, sand, moss, or other plunging 

 material." 



In the following sketch, for which, as 

 well as for the next, we are indebted 

 to Mr. Rendle, A is a transverse sec- 

 tion of Roger's conical boiler ; B is the 

 fireplace ; g, the tank ; c, the flow-pipe ; 

 (I, the pipe by which the water returns 

 to the boiler ; c, is the hole for the 

 smoke, which, joined to a flue, /, can 

 be made either to ascend the chimney 

 at once, or to pass round the house. 



The next sketch is a Pinery, fitted 

 up with Mr. Rendle's tank. 



It is described as " a very useful and 

 most desirable structure for the growth 

 of the Pine Apple, with a hollow wall, 

 recommended by all garden architects 

 in preference to a solid wall the heat 

 or cold being not so readily conducted 

 as through a solid mass of masonry." 

 Mr. Rendle might have added, that 

 hollow walls are also much drier. 

 Rendle's Treatise on the Tank System. 

 See Stove and Hotbed. 



RENEA'LMIA. The following should 

 be added to Alpi'nia, instead of forming 

 this genus. 



R, grandMa'ra (large.flowered), 1$, White, 

 New Zealand, (823, 



