126 GREENHOUSE CONSTRUCTION AND HEATING. 
In order to enable one person to work both the cords, 
and raise the blind at both ends simultaneously, the cords 
are sometimes arranged as shown in the accompanying 
Fig. 82, with pulleys at the corner as shown. 
i Da De ee 
= S| So Se 
a 
Fic. 82. 
Plant-Protectors.—Any narrow glazed construction of 
the nature of a portable frame, whether span-roofed or 
lean-to, may be classed under the term of plant-protector, 
though as a rule these are made considerably longer, as 
well as zarrower, than ordinary frames. An excellent type 
of plant-protector is shown in Fig. 83, in which it will 
be seen that the lights on each side are hung to the ridge 
in the usual manner, and are lifted up to allow of the 
contents being attended to. 
