my own experience of this
instrument, though favourable to its use, is still but limited, I cannot
do better than introduce here the following remarks of Mr. Beck, of
Isleworth, a very successful cultivator of plants, and one who has had
considerable experience in the use of these instruments. It will be
observed that Mr. Beck's standard for the orchid-house will be about
suitable for cucumbers.[4] Mr. Beck observes,--"The skilful gardener,
observing the pointer to advance with dryness and return with moisture,
will soon form a standard for himself, by which to regulate his stove,
greenhouse, &c.; still some general scale is desirable. Two conditions
must be carefully observed:--1. The instrument must neither be hung in the
sun, nor where it will be liable to get wetted or saturated. 2. It must
not be subjected to greater heat than is suited to vegetable life. For the
six months commencing with August and ending with January, 40 deg. in,
the morning, increasing to 60 deg. about noon, and declining again to 40
deg. at night, is about the right scale for the orchid-house; whilst a
range from 50 deg. to 80 deg. would be suitable for both the stove and
greenhouse in those months. In the other half year, February and July
inclusive, 30 deg. to 40 deg., morning and evening, running up to 80 deg.
in the middle of the day for the orchid-house; 40 deg. and 50 deg., and up
to 70 deg. for the stove; and 50 deg. to 80 deg. for the greenhouse, will
prove very suitable. The above scale is desirable, but I do not say it is
always attainable. Ours is an uncertain climate; sometimes a dry east wind
will almost parch us up; at other times a southerly one, with wet, will
cause a superabundance, which will have to be corrected, possibly by a
gentle fire, and a free admission of air. The alteration hereby effected
in the atmosphere of the houses will soon be evidenced by the hygrometer,
and mildew and fogging off be kept at a distance. Opposed to an excess of
moisture in the dull months of the year, is the dryness consequent on the
summer and autumnal sunshine. Then, during the heat of the days, the
instrument will seem to have run wild. Throwing water on the floors of the
houses, and every means of increasing the amount of moisture, seems but of
little or temporary avail; Simmons will go up, spite of all, to 90 deg. or
100 deg., and none the worse either, for it is still a faithful indicator,
and as sure as the day declines, and the heat of t