120 GREENHOUSE CONSTRUCTION AND HEATING. 
the bed. But many growers prefer to use loose sheets of 
glass, laid between lengths of light sash bar, tacked in place 
temporarily or otherwise, from front to back of the bed. 
These admit more light than sashes ; air can be given to 
any extent, and the whole, bars and all, can be easily 
removed when necessary. 
Double, or two-light, frames are usually constructed 
without any division, the inner edges of the lights being 
carried on a flat bearing bar, about 3in. by 14in. strengthened 
by a ‘‘parting piece” of 2in. by in. stuff, nailed on edge 
along the middle of the former, to separate the lights. This 
bar is dovetailed into and nailed to the ‘‘ box” or boards 
forming the front and back, and thus 
serves the additional purpose of holding 
the latter firmly in place. 
Pit-lights are supported in the same 
manner, and a division may of course 
be placed where necessary, and may 
consist of either brick or boards. 
Movable wooden divisions are very useful in long ranges 
of pits. 
Handlights and Plant-Protectors. — The old- 
fashioned handlight, made with small pieces of glass set 
in a framework of lead or iron, and which is illustrated in 
Fig. 76, was largely employed for protecting early 
cauliflowers, lettuces, vegetable marrows, etc., and for 
raising small seeds. They are still employed to some 
extent, but have been in a great measure displaced by pits 
and frames of the ordinary type. Some handlights are, or 
were, made with movable tops, and some without, but where 
a considerable number are required, as to cover.any extent 
