38 
IRON AND WOOD ROOFS FOR STOVES, &c. 
I remember witnessing this last summer, the destruction of the whole of a fine crop 
of grapes as well as the foliage, when nearly full swelled, in a gentleman's hothouse 
in Kent, which was erected of cast-iron about six years ago. The destruction 
occurred through the architect failing to allow a proper ventilation ; and to prevent 
the second house of grapes, which had then suffered severely, from sharing the same 
melancholy fate, the gardener, who is admitted to be as good a practical man as any 
in the kingdom, caused some holes to be made in the back wall of the house about 
one foot wide and three feet long, where he introduced shutters hung on hinges, 
by which means he fortunately succeeded in saving the second house of fruit, but 
not without great injury to the foliage. This unfortunate and unavoidable circum- 
stance was generally known in the neighbourhood of Seven Oaks, and observed by 
many practical gardeners, who can vouch for the accuracy of this statement. 
Having I think fully shown the advantage possessed by wood over cast-iron 
in these very essential points, the better growth of plants, and the saving of fuel, 
glass, and labour, I shall now give a description of my apparatus for heating by 
hot water, deferring until next month any further observations on the various 
modes of heatinp* houses. 
Figures 1,2, 3, and 4, are intended for houses of small dimensions, and the 
larger one, figure 5, for extensive houses : this boiler as well as the other is 
oval- shaped, and would be sufficient to heat seven or eight hundred feet of four inch 
pipe at a trifling expense ; for during the severest part of last winter, all the houses 
I have heated with this plan of boiler were kept up to their respective tem- 
peratures without burning one bushel of coal, the only fuel used being small coke ; 
and during the intense frosty night of January 19th of the present year, when 
at a quarter past six o'clock in the morning, the thermometer stood at 1 2 degrees 
below zero, or 42 degrees of frost, we had not the least difficulty in keeping the 
whole of the stoves and greenhouses at their respective temperatures. I have devoted 
much time and attention to heating houses with hot water for several years, but more 
particularly last season, and this winter up to the present time ; and from accurate 
calculations made of the number of superficial feet of glass exposed to the action of the 
weather, I am enabled, from watching the thermometers both out of doors and in the 
houses with all extremes of weather, to calculate most correctly the number of superfi- 
cial feet of pipe required to command (even with 42 degrees of frost) any given degree 
of heat requisite for stoves, greenhouses, or other buildings ; and the want of this 
practical knowledge and attention to this highly important part (the radiating 
surface) has been the cause of so many complaints against the system of heating 
by the circumvolution of hot water, all of which would have been prevented had 
the hot- water fixer devoted a few nights during severe frosty weather to these in- 
dispensably necessary calculations ; but then his remarks should not have rested on 
the observations made during a calm night of severe frost, for I have proved, by 
sitting up and watching the thermometers for whole nights together, that 16 
degrees of frost with a strong wind is more trying to a house, than a severe night's 
