PIT AND FRAMES. 123 
from strong sun only, with no shade whatever at other times, 
and in order to secure these conditions, and obtain the best 
results, a moveable blind of some kind becomes an absolute 
necessity. In private gardens of any pretentions, as well as 
in some of the better class of nurseries, most, if not all, of 
the plant-houses are consequently now fitted with blinds of 
some kind, and the question now arises, ‘‘ which is really the 
best of the several methods of fixing them”? A blind fixed 
so as to be easily rolled up and down at will is easily fitted 
to a small structure of not more than 15ft. oz 20ft. in length, 
but when a perhaps lofty roof of 50ft. or 100ft. in length 
has to be dealt with the task becomes much more difficult. 
There are two chief methods by which greenhouse 
blinds (which are always placed outside, of course) may be 
fixed :—(1) with a fixed roller at the top (apex of the roof) 
after the manner of an ordinary window blind, as 
at a in Fig. 79, and (2) with the blind fixed at the 
top and a moveable roller fastened to its lower edge, 
