148 Pohnaise Method of Heating Hothouses. 



showed them the reality of the broken reed upon which 

 they had rehed. Numerous instances have come under my 

 own observation, and a large orange house in the gardens 

 where I am this moment writing, presents a notable example 

 of this fact ; while the plants within it, sufficiently attests its 

 effects. 



In conversing on the subject of heating, I have often been 

 asked, what is Polmaise ? Before I say any thing more about 

 it, therefore, it may be proper for me to describe what Pol- 

 maise really is, and wherein it differs from other systems of 

 heating with hot air, which are more ancient than England 

 itself, and were in use long before the christian era. 



When this method w^as first brought before the public, un- 

 der its new fangled name, I went to Polmaise to examine 

 its working, and learn its details, with the determination of 

 adopting it ; I found the whole apparatus exactly as follows : — 

 A hot air furnace, (i. e., a furnace where the air is heated in 

 its passage over a red-hot plate with which the furnace is cov- 

 ered) was placed behind the back wall, about the centre of the 

 house ; immediately opposite the furnace, there was an aper- 

 ture in the wall, for the admission of the heated air into the 

 house ; directly in front and above this aperture, a woollen 

 cloth was suspended, which was kept constantly moist, by 

 a number of woollen skeins or threads, depending from a 

 small gutter, or naiTow trough, containing water, which is 

 fixed on a frame of wood, supporting both the gutter and the 

 cloth, the lower edge of the latter reaching the ground : the 

 cloth is made thicker in the middle, in order to equalize the 

 heat, an arrangement which was indispensable ; for if the 

 cloth was of an equal thickness all over, the centre of the 

 house would have been heated to a scorching degree, while 

 the ends were comparatively cold. By means of drains un- 

 der the floor, the fireplace was supplied with air, from inside 

 the house, part of which is used for the combustion of fuel ; 

 the rest passes over the heated plate, and enters the house 

 through the aperture above mentioned. 



Such then, is the real system of Polmaise heating, as ori- 

 ginally applied at Polmaise, and which sprung out of the fol- 



