IMPROVEMENT OF FORCING-HOUSES. 
159 
and durable, ought to contain a larger proportion of sand than the cupidity of the 
lime-burners usually allows ; but this proportion depends greatly upon the quality 
of the sand ; if it be that of reduced gravel, or such as is dug from a pit, and com- 
monly known by the name of sharp sand, it may safely be considered siliceous, or 
flinty ; and therefore calculated to fix and consolidate a large portion of water 
in the form of hydrate of lime. But if it consist principally of reduced limestone, 
its activity as a chemical agent will be inconsiderable. We however assume, as a 
standard, that the sand employed shall be the screened scrapings or drift of a high 
road, which is repaired with gravel ; and in that case, from three to four proportions 
of such sand should be admixed with one proportion of the best slaked lime. 
Mortar so prepared will Jisc an abundance of water (that universal cement) and 
consolidate it in the form of a hydrate of silex and lime, a substance that the wear 
and tear of ages will produce little or no impression upon ; witness the solidity of 
those vestiges of Roman structures, which have withstood the pelting of the storm 
for two thousand years. Houses, pits, or walls for every process of horticulture, 
can be erected by the method proposed, which will be superior to those in common 
use, and at a greatly reduced expenditure ; they are lighter and less liable to settle, 
and yet stronger than if built solid ; they afford equal, if not better, protection to 
plants and trees, and may be heated by linings (or flues) permitting the heat of 
fermenting materials to pass through them with considerable freedom ; and the 
plate of air within, being once effectually warmed, retains its temperature for a 
considerable time. 
But it is not only in the brickwork of an erection that economy may be prac- 
tised ; timber may be purchased at the wharfs and yards ; be sawed and cut lo order 
at a price far below that which is imposed by carpenters. Many persons can 
handle the saw, plane, chisel, and other requisite tools, with a good deal of dexte- 
rity ; and we have our eye now upon a range of glass structure, where every part 
of the work has been executed by the juniors of the family, with much neatness and 
precision ; but if labour be hired, the work will still be conducted with comparatively 
hght expense, provided the materials be purchased with judgment. Glass is of 
great consequence, and till recently the panes of greenhouses, &c., werci much too 
large; oblong squares, five and a half inches long, and three and a half wide, or six 
inches long by three broad, can be obtained at the rate of about seven-pence per 
square foot of the wholesale glass merchants ; and if the laps be made not wider 
than from one-twelfth to one-eighth of an inch, the glazing will he efficient, and 
little expensive. 
If persons be deterred by the dread of incurring a considerable expenditure, 
from an enjoyment of nature's choicest beauties, these few hints, offered by one who 
is fully acquainted with the truth of the facts he has stated, may prove not only 
interesting, but very acceptable ; at all events, the motives of their writer can 
scarcely be misunderstood. 
