f,0 
IRON AND WOOD ROOFS FOR STONES, &c. 
which amounted to about seven or eight lengths altogether, one third of the joints 
burst after it had been used only three or four times. At intervals they continue 
to crack to this hour, and will do so until room be allowed for the expansion of the 
pipes where they pass through the stone. Having thus given a few brief instruc- 
tions for the management of hot-water apparatus, and knowing that there exists a great 
diversity of opinion relative to the quantity of water a boiler should contain, and 
of the dimensions of the water way both in pipes and boiler, so as to secure a 
regular and lasting temperature, I hope it will not be considered presumptuous 
in me to offer a few observations on that subject, and leave the impartial reader to 
decide the question. It is natural that every constructor of hot-water apparatus 
should be prejudiced in favour of his own peculiar plan — the child of his own mind. 
Hence it is that the prescribed dimensions of the conducting pipes vary from half 
an inch to five or six inches in diameter, according to the particular plans of different 
individuals. I shall merely give my own judgment on the proper sizes, without 
commenting upon any peculiar plan. It is my opinion then that a hot-water 
apparatus, to answer all desired purposes, should be so constructed as to avoid 
either objectionable extremes, since pipes of too large or too small dimensions are 
equally to be avoided, and this for reasons which I could easily adduce, were it not 
that I desire on this occasion to confine my remarks to boilers formed of series of 
pipes varying from half an inch to two inches, which I admit have a great 
advantage over boilers containing large bodies of water, inasmuch as they become 
hot much quicker. Then it must be recollected, that the larger body when once 
heated will remain hot twice or three times longer than the other ; and I have 
proved by observation, that a four-inch pipe, which contains double the quantity 
of water which a two-inch pipe is capable of receiving in a house of the same 
temperature, will retain its heat for more than double the length of time. 
When boilers are used that have such small water ways and small pipes, they 
require more attention, and cannot be left at night with the same safety as boilers 
and pipes containing larger bodies of water, seeing that the former cools so much 
more rapidly than the latter. Nevertheless, to err in the other extreme, by having 
boilers and pipes to contain very large quantities of water, would be a great waste 
of fuel, and by no means calculated to answer to the satisfaction of all parties so 
well as a boiler and pipes of a medium size : it is my opinion, therefore, that in 
neither boiler nor pipes should the water way be less than three inches, nor more 
than four inches, and the boiler should be so constructed without complication as 
to expose the greatest possible surface to the action of the fire. This would be 
found the most economic boiler for fuel and effect ; for I have always remarked that 
the greatest object of persons who heat their houses with hot water is the saving 
of fuel, &c, which is very considerable when compared with the expense attendant 
on a badly-constructed flue. Besides, an opportunity is afforded of heating 
several houses at the same or very little more expense ; this I have always con- 
sidered of the greatest importance, particularly when a gentleman's establishment 
