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