404 Reviews and Extracts. — Horticulturey Sfc. 
dung instead of fire heat. This we are perfectly satisfied will answer well. 
Nutiibers of gardeners in small places introduce a little spawn into their 
cucumber and melon beds, and after the cucumbers and melons are over, by 
putting a little new lining, abundant crops of Mushrooms are produced 
throughout autumn and winter. 
Mr. Callow's observations and descriptions are explicit and satisfactory: 
he introduces the subject, by stating that the Mushroom has been culti- 
vated along time with various success, he proceeds to observe, that in 
autumn the Mushroom is produced in greater abundance and vwth more cer- 
tainty than at any other period. This he very justly attributes to the humid 
state of the atmosphere at that period. On the system Mr. Callow has recom- 
mended, we are satisfied excellent crops may be obtained, but we conceive the 
expense will be greater than on the system of fire heat, as in the first place, 
there must always be a regular supply of hot dung, which is very often diffi- 
cult to be met with; and secondly, the price of dung, and the consequent 
labour of turning &c. of the linings, will eventually be found to over-balance 
the expense of coal, and trouble of attendance on the fire. 
Mr. Callow lays great stress on the undue exhalations which beds heated 
by fire are subject to. This might be remedied by a canal of water placed 
on each side of the flue, or a simple hot-water apparatus might be adjusted, 
and the pipes left open in various parts, which would keep the air of the house 
as damp as would be necessary. 
" The uncertainty in the produce from dung ridges made in the open ground, 
and front beds made in cold sheds, arises froju a deficiency of bottom heat, and 
from damp, and from other causes; whilst the loss of crops, which often occurs in 
forcing Mushrooms in houses warmed by fire, may be attributed to the arid state 
of the atmosphere, which the fire necessarily creates, and this being uncongenial 
to the habits of the vegetable, it consequently does not flourish in such situations. 
The fire-heat also causes too great an evaporation from the bed, which renders it 
so dry that it soon ceases to produce ; and if water should not he supplied in the 
most careful manner it will destroy the spawn. This difficulty often occurs, and 
from it, with a fire heat, there is no possibility of escape Nor is to be denied, 
that Mushrooms, forced with the aid of fire are nuich tougher, and also less juicy, 
than those which are produced on ridges of very warm dung." 
" The atmosphere, which, at first view may notseem to he of much consequence, 
and has escaped the notice of vpriters who have treated on the subject of Mushroom 
growing, is nevertheless of the first importance ', and a damp, heated air, seems 
in fact, to he the desideratum so long required to insure luxuriant crops through- 
out the year ; for while this moist air is congenial to the habits of the plants, so 
at the same lime it remedies the evil of undue evaporation, from tiie bed on which 
they grow." 
"When a large supply of Mushrooms is required, two houses at least are neces- 
sary. These should he so situated that the one for sunnner use, should slope 
towards the north, or north-east ; and the other for winter use, should slope 
towards the south, or south-west. If the ground on vphich the houses are built be 
wet or damp, the earth uiust be removed two feet deep, and the space filled up with 
loose stones or rubbish, [fig. 65 & 66, iy] for it is absolutely necessary that the 
floor of the bed should be dry. The back, and end walls, {Jj) are built of stone 
or brick. The front (') is to be hoarded up with inch boards, and plastered on 
the inside with a thin coat of mortar. The roof (^) shoidd be covered with a thick 
coat of thatch. An aperture with a door i? to he left at each end of ihe house, 
