80 
MODIFICATION OF POLMAISE HEATING. 
other radiating surfaces of dry heat, which require the qualification of wet blankets. 
What we, and every cultivator of ornamental or fruit-bearing plants require, is an 
atmosphere equable in its temperature, and rendered moveable, not by currents of 
cold air, but by the interchange of air from without (warmed in its approaches) with 
that within, which has already been brought to the desired heat by the operation of 
the flues or hot- water machinery of the erection. 
Eeferring to the ground-plan, it is seen that the portion which terminates at the 
mark 18/, represents the original extent of the house as we described and figured 
it in December, 1845 : — No. 1 is a part separated now by a glazed partition (G-.P.) 
put up last Christmas, with the object of forcing the plants contained therein by 
the whole power of the flue ; and therefore, in conformity with that object, 
the course of the heat is cut off from the left division of the flue, and passes 
around the right-hand pit exclusively, as indicated by the two darts near o. 
No. 2 includes the addition lately made, and also that part of the original building, 
which with about two-thirds of the left-hand pit (2) is separated by the dotted line 
marked G. D. Thus the house comprises two departments ; one, the smaller, that 
can with facility be brought up to full pine temperature, or if devoted to ornamental 
purposes, to that degree of heat which will be suitable to the cinnamon (Cinnamomum 
verum) and other tenderest plants of the tropics ; while the other and larger may 
be either used as a simple greenhouse, or otherwise so warmed as to favour the 
culture of the hardier subjects which we meet with in ordinary plant-houses. 
These arrangements, desirable as they always are, especially when effected with 
the chaste elegance which has been displayed in the present instance, would not 
have elicited our remarks, since it is by no means uncommon to meet with graperies 
and plant-houses so divided by glazed partitions. But here we find that by the 
ingenuity and happy forethought of the proprietor, the very essence of the 
" Polmaise System " has been exemplified, and its principles reduced to practice by 
the simplest contrivances, while the house has also been supplied with rain-water in 
a way equally novel and convenient. 
F, in the plan indicates, as before stated, the position of the furnace and stoke- 
hole. It was described in the former article, and comprises all that is and was the 
object of the talented projector, as to the surfaces radiating heat. The furnace, 
which is nothing more than a well-built common brick oven, is provided with a 
close-fitting ash-pit door. From the furnace there passes a diagonal neck (en) a 
little more contracted at its outlet from the fire, and it enters the flue proper at the 
angle marked by the first curved dart ; this flue is built of three bricks on edge 
pargeted within ; it is elevated by a wall of bricks underneath it, and forms two 
pits, which are fully a yard deep, and therefore prepared to receive a mass of leaves, 
dung, tan, or other material, which may suit the purposes of the gardener. As the 
flue enters, so also in like manner it carries its smoke by a corresponding diagonal 
return channel (marked ex) into the chimney, which is erected at the north-east 
corner of the building. 
