THE ORCHID WORLD. 
135 
tiffany blind is much lighter than the lath, and 
a larger expanse of blind can be rolled up 
at once, thus effecting- a saving in time, a rather 
important thing when many houses have to 
be shaded quickly. But these are really minor 
matters, for what we are mostly concerned 
with is the direct action and influence of each 
as a shading agency. 
It requires little discernment to convince one 
that what would be just sufficient shading for 
March would be decidedly too little for July, 
and vice versa, and yet we use the same blinds 
for all seasons. This is decidedly wrong, and 
can only be defended on the grounds of econo- 
mising in the first outlay and the trouble of 
taking down, re-fitting and storage. Thin 
tiffany lying actually on the glass would give 
sufficient shade at the beginning of the shivding 
season, and the same blind removed some 
distance from the glass would be just right a 
little later. The lath bhnds, fixed some dis- 
tance from the glass, are decidedly too cold 
to keep off glimpses of sun on cold, windy 
days, for immediately they are run down a big 
drop takes place m the temperature of the 
house. Our best efforts should be put forward 
to utilise to the full the heat from the sun 
during cold, bright days instead of shading 
and firing at the same time ; and what seems 
to me a question of more moment than the 
material used for shading is the distance it is 
fixed from the glass. A parasol held well 
above the head gives delightful relief from the 
sun's rays, but if brought down into contact 
with the head gives little relief from the heat, 
although the sun is obscured. I have an idea 
— and it will require no great inventive genius 
to carry it out — that it should be possible to 
construct a collapsible light framework on the 
top of the more important houses, say the cool 
and warm division where seedling raising is 
carried on, and which could be lowered on to 
the glass and raised at will. This would be 
a permanent and solid arrangement worked 
something on the principle of a folding chair. 
On cold days this could lie on the glass, when 
the plants would benefit to the full from the 
heat, and on warmer days it could be raised 
sufficiently to allow the air to have full play 
between the blind and the glass, so that the 
right temperature could be maintained. Every 
practical grower realises that he has to shade 
too much in the spring, but is unable to help 
himself. 
For plants that are sensitive to the direct 
rays of the sun — and I would include in these 
Cypripediums, Phalaenopsis, and other pseudo- 
bulbless Orchids — I should be disposed to 
favour the canvas or tiffany blind, and for 
epiphytal pseudo-bulbous Orchids, such as 
Dendrobiums and Cattleyas, the lath blinds. 
My only objection to the cloth blinds, however, 
is that during hot, still days it is difficult to get 
buoyancy into the houses, as the air from the 
top ventilators has little freedom of escape 
unless the blinds are fixed an unreasonable 
distance from the glass. Where, however, the 
houses have been built with a lantern system 
of ventilation — /.('., where the apex of the 
house may be lifted by a mechanical device 
and air admitted and allowed to escape above 
the blind attachments, this objection is 
removed. 
The heat may be kept down in the Odonto- 
glossum houses very effectively by having 
double shading, one a foot or so from the 
glass to roll down, and one lying nearly on 
the glass to roll along. The underneath one 
alone will frequently be sufficient, and, on the 
other hand, the top one alone may be sufficient, 
a nd only on exceptionally hot days will both be 
required ; but it is well to be provided with both. 
Cloth blinds give less light, but are warmer 
than the lath blinds. There is always a 
cushion of warm air between the former and 
the glass, as the air escapes with difficulty 
through the close meshes of the cloth. This 
cushion of warm air does not remain between 
the lath blinds and the glass, for the obvious 
reason that there is a ready escape for it, so 
that, while allowing the direct rays of the sun 
to play on the foliage, the latter are still the 
cooler blinds. 
To use a permanent shading of whitening 
is very risky, as the season may be a dull one, 
but some growers in sunny localities favour it. 
They put on a thin coating, and argue that 
on many days it saves their putting the roller 
blinds down. This whitening of the glass can 
only be used to supplement the other shading. 
