February 2, 1893. ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
87 
As suggested by your correspondent, the length of time the 
spawn took to run was partly accounted for by the depth it was 
buried ; and late in spring before the border was done up we had 
no fire heat, the house being naturally a cold one. We expect to 
gather Mushrooms next autumn from the same border. Even now, 
though the house is empty and has had no more heat than to keep 
out frost in severe weather, we see one or two fine Mushrooms are 
appearing. 
We are only beginners in Mushroom growing, and groping our 
way ; also like your correspondent, hunting after information and 
taking advice, and experimenting as often as we can. By another 
year we may strike on something new ; at all events, we shall 
be able to speak with more confidence and experience in this new 
way of growing what is undoubtedly the most profitable crop 
one can produce. I shall be glad to give to all interested any 
hints I can through the Journal of Horticulture. —W. Buchanan, 
Forth Vineyard, Kippen. 
EXPERIENCE IN HEATING. 
Heating glass structures by means of hot water being a matter so 
closely connected with the cultivation of flowers and fruits, it is of 
great importance in growing them successfully to know something of 
the principles by which hot water is conveyed. I will try and make 
the subject as clear and simple as possible, that it may be readily under¬ 
stood by those whom it would be most likely to benefit. Mr. Fawkes, 
in his treatise on “ Hot-water Heating,” thus describes the principle 
involved :—“ The construction and working of a low pressure hot-water 
heating apparatus is based upon the fact that water is at its greatest 
density and minimum volume at 39'2° Fahr. Upon the temperature 
being raised above this point the volume increases and the density 
decreases. In other words, a cubic inch of water at 40° weighs more 
than a cubic inch at 60°. It is obvious, therefore, that if we take 
a given quantity of hot and cold water and allow the two to inter¬ 
mingle, the immediate result of the difference in the respective 
specific gravities will be that the latter will push the former upwards, 
so that the hot water will lie at the top, the cold water at the 
bottom.” 
Thus we see that water upon being heated becomes lighter, expands, 
and rises upwards, and the colder water being of greater density lies at 
the bottom. This is sufficient for all practical purposes. It is rarely 
that a gardener is called upon to erect a hot-water apparatus ; this 
more intimately concerns hot-water engineers. Those who wish to enter 
into fuller details can do so by consulting any of the works dealing 
with the matter. So long as we know the principles upon which the 
circulation of hot water depends, it is sufficient to enable us to regulate 
the apparatus by which our structures are heated. The first thing to 
consider is the number of structures to be heated and the kind of boiler 
that is likely to suit the purpose best. Boilers are numerous, and some are 
better adapted for certain places than others. The boiler that is the 
simplest in construction, and which exposes the largest amount of sur¬ 
face immediately over the fire is the best, and in my experience I have 
never found any to surpass a good terminal-end saddle-boiler. 
Cisterns and Pipes. 
Having selected the boiler, we must decide upon the position in 
which it is to be fixed, and in this matter the stokehole should be con¬ 
structed sufficiently deep to allow of a proper rise in the pipes to be 
affixed. Due regard must also be had as to whether there is likely to be 
any danger from rising water or its ingress in any way, for this would 
be liable to extinguish the fires, perhaps when the heat was most 
wanted. A space must also be allowed for holding the fuel near at 
hand, and this is best arched over with brickwork, the ground levelled, 
and an opening left at the top, to where it may be carted and easily 
thrown in. The cisterns for supplying the boiler should be fixed several 
feet above it in the stokehole, and ought to be fitted with a ball-tap, the 
feeding pipe brought from the bottom of it and connected with the 
lower side of the boilers. For large boilers a 2-inch iron pipe would be 
required. If a pipe of smaller diameter is used it should be of lead, 
and brass fittings employed on approaching the boiler connection, for 
fear of corrosion, which might be mischievous. An expansion pipe 
should be carried up from the top of the boiler into the cistern, to guard 
against any mishap. Where cisterns have to be filled by hand, great 
care must be taken that they never become empty. The chimney should 
be built so as to create a good draught, upon which much of the 
efficiency of the apparatus will depend. Now, having seen that hot 
water rises to the highest point, we affix the flow pipe to the top of the 
boiler, add other connections, always with a gradual rise, until the 
highest point is reached that we wish to proceed to, and then, with a 
corresponding fall, the return pipes are brought back and connected 
with the bottom sides of the boiler, where the colder water is in turn 
heated and sent along its way. 
Main pipes underground should be covered with some non-conducting 
material, and be in trenches of brickwork, supported at the connections 
by piers, and upon these, under the pipes, short iron rollers, strong 
enough to carry the weight, to allow of contraction and expansion 
should be laid ; this prevents the straining of the joints which makes 
them liable to leak. Main pipes are usually 4 inches in diameter. 
These mains must be laid in the most convenient manner for connection 
to be affixed to them for the various houses which are required to be 
heated from them. 
Large and Small Boilers. 
In some establishments one powerful boiler heats the whole of the 
structures, another being erected by its side in case of requirement or 
accident. This is a good plan where the houses are close, together, 
and for convenience in stoking; but this system is faulty when the 
houses are scattered and situated a long distance from the boiler, and 
where early forcing is practised. Two powerful boilers heat the whole 
of the structures under my charge, some nearly 300 feet away and 
containing between 9000 and 10,000 feet of piping, one boiler usually 
being used. I find them anything but economical in the earlier months 
of the year. Where so many pipes are underground there is a great 
waste of heat and fuel ; in early forcing, when a cold frosty night is 
succeeded by a bright day, and the fires are stopped early, it takes 
much hard firing to get the pipes warm again by nightfall with such a 
large volume of water to heat, and wasting itself in a great measure 
underground. Again, with such a complication of valves, and various 
levels of pipes, it is extremely difficult to regulate the heat with any 
degree of precision. At times it seems inclined to rush in one direction. 
Fig. 13.—ZYGOCOLAX VEITCHI, (^SeepageU.) 
at others just the reverse, and it needs the greatest caution when going 
the last round at night to leave everything safe. Perhaps the attendant 
may find it necessary on his last journey to turn a little heat on cer¬ 
tain houses when there is prospect of a sharp frost, when a rush of 
cold water into the boiler takes place and the heat robbed from houses 
where most needed, and failing a bothy on the premises or a night 
stoker this is most inconvenient. 
Forcing houses are more satisfactorily managed when they are heated 
by boilers fixed at the back or north side of them, presuming they have 
a southern aspect, which all such houses should have. By this system 
the heat can be more quickly circulated and also shut off, than when 
it has to be conveyed a long distance by one large solitary boiler with 
numerous connections, for this entails a waste of fuel in heating a large 
volume of water, probably early in the season, for one or two houses 
only. A smaller boiler close by performs its work more efficiently and 
economically. 
Arranging Hot-water Pipes in Fruit Houses. 
In arranging hot-water pipes for fruit houses, the first thing to 
consider is what occupants are to be grown therein, and what degree of 
temperature will be required to cultivate them successfully ; whether 
the houses are required to produce ripe fruit early in the season, or at a 
later period when the sun’s rays gain more power, for according to their 
requirements so are the houses constructed for their various purposes, 
and the amount of piping regulated likewise. We will take an early 
vinery from which ripe Grapes are expected by the end of May. For 
this purpose the lean-to form is undoubtedly the best, and such houses 
are usually erected against walls. That this form is best is obvious, as it 
