158 
IMPROVEMENT OF PORCING-HOUSES. 
third of the materials, great strength of building, and increased security as respects 
e<iuable temperature. The mode of structure was, years ago, described in the 
Horticultural Transactions, and in Loudon's Encyclopaedia of Gardening; but 
either prejudice or misconception has operated against its adoption, for we never 
meet with it in any of the gardens. It is therefore to be hoped that the notice now 
taken of it, will excite the attention of many of the readers of the Magazine of 
Botany, and induce some persons to give it a fair trial; in that case its merits 
cannot fail to become apparent. 
In the ordinary way of building walls it is calculated that one hundred bricks 
will form a square yard of nine-inch work; but in the structure which it is our 
object to recommend, a saving of about one brick in three may be effected. The 
passages to which we refer in the Encyclopaedia by Loudon, are to be found at 
par. 1361, page 305, edit. 4th, 1826. The following is a correct and sufficient 
extract : — " The cellular wall is a recent invention, (^Horticultural Transactions ^ 
vol. IV.), the essential part of the construction of which is, that the wall is built 
hollow, or at least with communicating vacuities, equally distributed from the sur- 
face of the ground to the coping. If the height does not exceed ten or twelve feet, 
these walls may be formed of bricks set on edge, each course or layer consisting of 
alternate series of cells, nine inches in the length of the wall, by three inches broad. 
The second course being laid in the same way, but the bricks alternating or breaking 
joints with the first. 
Figs. 1 and 2 exhibit bird's- 
eye views of two single courses of 
the cellular work, looking down 
upon them from above ; all the 
bricks are set on edge, the two ^ J"^^ ^^"j 
stretchers being met by an ender, n ' I LL — L^^J_.--_JJlZI1^3-lZ-J^ 
thus forming the cells c, a succes- e e e e e e e e 
sion of which is made by every three bricks. Fig. 2'*shows the enders, e, e, e, 
which cross the two stretchers of everyj inferior course, thus binding the work in a 
way far more secure than that commonly practised in solid walls. 
Fig. 3 shows the face of the wall. 
^^^^^^ 
II ..11 ! 
11-11 ir i-i II 1! 
11 1111- li 11 1 1 1 1 
■11 II II 11 II li II- h T 
the stretchers and enders lying in 
alternate order, c, h, a—f are the 
foundation solid courses, a and h 
being of fourteen and c of nine-inch c 
work. Iw forcing houses their con- ^ 
struction possesses the peculiar ad- 
vantage of interposing a plate of air throughout its whole surface ; and as air is a 
bad conductor of heat, equabihty of temperature is provided for. In common garden 
walls — one of which the writer has just caused to be erected — every convenience 
of a solid wall is secured ; and it is understood that the structure will act perfectly 
as a flued wall. The bricks and mortar ought, however, to be of the best quahty, 
and the workman should lay his bricks with great precision. Mortar, to be good 
