195 - THE ORCHID REVIEW. [JuLy, roto. 
or below 75° F. Generally it is about 85° F. Summer night minimum 
about 68° F.-70° F. 
The fire is hardly ever allowed to go out by day except in the hottest 
summer weather, and it is always alight at night whatever the weather. It 
gives less trouble thus, and is always at hand to check a sudden fall in 
temperature. A little warmth in the pipes allows of a freer use of the 
ventilators, even during the day, than would otherwise be safe. As previously 
indicated, the pipes can be kept down to 95° F., and on a hot spring day 
the house frequently stands at near go° F. for hours. On such a day a very 
great fall in temperature must generally be looked for towards evening and 
prepared for by allowing the temperature of the pipes to rise before the fall 
is expected. If the outdoor, indoor, and pipe temperatures, the force and 
direction of the wind, and the nature of the fire, are constantly noted for a 
time, it becomes very easy to maintain any temperature that may be required, 
and the probability of drip may be foreseen and guarded against. I use 
several thermometers in different parts of the house. It is necessary to 
find suitable places for thermometers ; they will not tell the truth if exposed 
to sunlight or even when hung near a mass of brick or woodwork at a higher 
temperature than that of the house. 
I use as much bottom ventilation as the weather and the necessity for 
maintaining a sufficiently moist atmosphere allows at all seasons, but not 
all day. I like to open one or two top ventilators on any really mild day 
about noon in winter for, say, five minutes. In summer one or two top 
ventilators are left open for an hour or two at midday on warm days, and 
on the leeward side, but generally I use the top ventilators with great care, 
as they are specially apt to produce draughts and an excessively dry 
atmosphere. 
I regulate the moisture in the atmosphere by the hygrometer (it is 
hopeless for an amateur totry to do without this instrument) and observation 
of the weather. During most of the day in summer I try to keep about 
2°-3° below saturation; for an hour or two at midday the atmosphere may 
be allowed to get considerably drier. In winter I keep the atmosphere 
nearly as moist as in summer so long as too much drip is not produced. If 
there is much drip, or the spray has accidentally been used too heavily, I 
keep the hygrometer at 6°-7° below saturation for an hour or two, in 
order to allow the axils of the plants to dry. 
On warm spring and summer days I use a fine spray in the morning and 
afternoon, but with great caution, lightly, and with due regard to the 
weather expected. All the plants benefit by the use of the spray, but it is 
better to let a hot day pass without using the spray than to risk the 
accumulation of water in the growths of C. bellatulum and its allies. The 
cool Cypripedes are much less sensitive to injudicious spraying, &c. Too 
