The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1852-02-03 00:00:00

HORTICULTURE.

The exciting topic of the horticultural world at present
is certainly the proposition of Mr. Ewing, gardener at
Bodorgan Castle, to erect hollow glass walls for fruit
trees, as a substitute for those of brick, in use at present.
So feasible does this plan appear, that a patent has been
secured, and gardeners are all eager to try the expe-
riment. Where the means are plentiful, this is desirable;
but if economy is sought for, we should certainly
advise a little delay. It must be confessed that a more
captivating idea has hardly ever been promulgated in the
gardening world ; and that it will have many advantages
there can be no doubt —tor instance, the ease with which
glass walls may be removed, and their decidedly orna-
mental appearance. But though these points are desira-
ble, they are not the principal objects sought for. Shel-
ter, warmth, and support for the trees, and protection for
the garden, are the uses of ordinary walls : if all these are
found in the Patent Glass Walls of Mr. Ewing, there is
the strongest reason why they should be adopted, for they
would add to this their elegant appearance. We, how-
ever, very much doubt their utility. As shelter to the
enclosed garden and the trained trees, they would proba-
bly he equal to brick walls ; but we doubt their warmth.
Even if fire-heat be used to increase the interior tempera-
ture, the exposure of such a large surface of elass to the
cooling effects of the wind would tend to the injury of the
enclosed espalier trees ; besides which, the walls being per-
fectly upright, they would not receive so much heat from
the sun, and the bad-conducting power of glass would be
a poor substitute for the heat-absorbing properties of
dark-coloured brick walls. There seems to be one point
entirely lost sight of in all calculations respecting the
erection of horticultural structures, and it is this: the
heat of the sun's rays does not pass, like light, directly
through glass, and even if it did, upright walls would be
unphilosophical, because even the light ray is refracted in
passin;, through the denser medium ; hence it is that roofs
sloping so as to receive the rays of the sun at a moderate
angle of incidence, have been found to succeed hest.
But the heat which passes through glass is transmitted,
that is to say, it acts first by heating the surface which
communicates by conduction the heat so acquired to the
under surface, from which it radiates through the enclosed
atmosphere of the structure. in ordinary glass plant•
houses, the largest possible amount of surface is exposed
to the influence of the sun's rays, by giving a considerable
pitch to the root ; consequently, the radiation from the
internal surface is correspondingly large ; besides which,
the back wall and soil receives anti retains by absorption
very much of the heat. so transmitted. In the class walls
these advantages cannot be secured ; no sooner will the
hat be transmitted through one side, than by the same
process it will be lost, through the other; while the sur-
face of soil exposed to its influence is so small that it will
not counterbalance the effect of external dampness. All
these points should be well considered before any great
outlay is incurred ; as to the protection afforded to pro-
perty, glass walls have no claim to the least consideration.