552 THE HOT-HOUSE. [Oct. 
A frame for this purpose should be made about nine or ten feet 
long, four to five wide, three and a half high in front, and five in the 
back part, with sashes well glazed and fitted as close and neat as 
possible, so as to slide up and down freely. This frame should be 
placed in a dry well sheltered situation, exposed fully to the south, 
and where it can have the benefit of the sun during the whole day. 
It should be filled with fresh well prepared tan, to the depth of 
three feet when settled, and the pots plunged therein to their rims, 
he smallest sized plants in front, the largest towards the back 
part. 
The frame should be entirely surrounded with a large quantity 
of the fallen leaves of trees to its full height, having still more in 
reserve to add, as the others sink and contract in bulk, in conse- 
quence of fermentation and pressure; always keeping them full up 
to the top of the frame on every side; the leaves will soon heat and 
cause the tan to ferment, and between both a fine glow of warmth 
will be kept up in the frame during the whole winter; this with the 
assistance of a suitable covering of mats, boards, &c. at night and 
in severe weather, will keep the most tender plants in health and 
good condition. 
Linings of hot horse-dung may be substituted in place of leaves, 
but the latter is preferable, on account of its slow, steady and long 
continued heat. 
Oak Leaves used as a substitute for Tan. 
As oak leaves abound in almost every part of the United States, 
it is of some importance to know that they may be used in forcing 
pits of every kind, in place of tanner's bark; and with advantage, 
their heat being constant, regular, and continuing for a long time, 
often for an entire year; whereas bark generally turns cold soon after 
its violent heat is gone off, which obliges the gardener to fork it up 
frequently, in order to revive the heat. 
The sooner the leaves are raked up after they fall from the trees, 
the better, as the quality and fermenting substance, will naturally 
decrease during the time they are exposed to the weather. 
When raked up they should be carried immediately into some 
open shed, and there thrown into a heap to settle and ferment.— 
In this place tread them well, and water them a little if you find 
they are rather dry. The heap should be at least six or seven 
feet in thickness, and covered with old mats as well to promote a 
general fermentation as to prevent the upper leaves from being 
blown away by the wind. They should be suffered to remain in this 
state for four or five weeks, by which time they will be properly 
prepared for the pits, and will not settle down much after. In put- 
ting them into the pits, if they appear dry, water them a little and 
tread them in layers, exceedingly well, till the pits are quite full: then 
cover the whole with tan to the thickness of two inches, and tread 
it weli till the surface becomes smooth and even. On this place your 
pots of pines or other tender plants in the manner they are to stand, 
filling up the spaces between them with tan as you proceed, row by 
row. 
