79 
MODIFICATION OF POLMAISE HEATING. 
It is contrary to our adopted rule to make any allusion to former articles ; yet, 
1 the present instance, it has become necessary to deviate, in order to convey a 
brrect idea of what, upon conviction, appears to offer a great improvement in the 
instruction of propagation-houses, and indeed of every glazed erection designed for 
pe purposes of forcing. 
We refer the reader who possesses the back numbers of this Magazine, to page 
53, No. 143, of December 1845, for the mere ground outline of a vinery and its 
ue, which at the first slight inspection struck us as being the most complete mode 
f any simple erection that had ever met our notice. At that period the flue had 
I ot been tried ; the party who planned the arrangements had proceeded in detail, 
is first object being to amuse himself with a few flowering plants, and at the same 
ime to procure, by simple protection, a superior crop of grapes. The house, therefore, 
ms without a flue at its first erection ; it was lofty, with back and front moveable, 
wing lights, fixed roof, side-sashes, and rather low walls, so that in fact it was 
s light and airy as the best glass and the first order of workmanship could render 
t. It was, however, soon discovered that a flue was essential, and the one which 
ormed the subject of the plan alluded to, was erected. Since then a further 
ddition of two extra lights has been made, and as the building is now 
lerfected in all its parts, and that portion of the flue and its appliances which bear 
ipon the proprietor’s immediate objects are in full operation, we must enter into a 
flore minute description of its capabilities ; and, in the first place, recur to the 
dan : — 
ch 
By the annexed simple outline, we hope to prove the legitimacy of our title, 
md thus to demonstrate that every available principle of the “ Polmaise System ” 
)f excitation may be brought into practice in a manner equally safe and beneficial, 
livested of all the risks which must arise from masses of brick-work containing 
hel in a state of intense combustion, with their appendages of iron plates and 
