MATS FOR COVERING PITS AND FRAMES. 569 



of very rougli wood ; are narrow — not exTceeding four feet 

 in width ; and arranged in close lines completely immersed in 

 the heating material. They are usually about twenty inches 

 high at the back and fourteen in front. Undoubtedly the 

 principle is better and cheaper than our own. We employ 

 large and well-made frames in private gardens j and for the 

 most part place them so that all but the base is exposed to 

 the influence of the weather, and the plants therein are 

 more liable to changes of temperature and cold. By having 

 the frames narrow^ all the sidework rough and cheap, and 

 the frames placed in close lines, we get the greatest amount 

 of heat at the smallest cost. By having nothing but the 

 surface of the glass 



exposed, little heat is Fig. 322. 



lost, and when the 

 frames are covered by 

 the neat, warm, and 

 flexible straw mats, 



they are as snug as Narrow frames used for forcing by the market 

 could be desired. gardeners of Paris. 



When it is simply 



desired to preserve bedding plants through the winter, 

 the spaces between the rough-sided frames are merely 

 filled up with leaves and slightly heating materials. About 

 two feet of space is left between each frame, or just 

 enough for the convenience of the workmen. Generally 

 they are put together by the workmen of the market 

 gardens : two stout posts being driven firmly in at one 

 end, and an end-board nailed to them. Then at every four 

 feet or so minor posts are driven down, and the rough front 

 and back boards nailed to them. Numbers are also made 

 on a plan by which they can be readily taken to pieces and 

 stored in a small space while not in use. By this means 

 the ground covered by forcing frames in winter is cleared 

 for ordinary open-air crops in summer. 



Mats for Covering Pits and Frames. — In our cold 

 and variable climate, the winter covering for many minor 

 glass structures is of the greatest importance. It is a thing 

 at present managed in a very expensive and by no means 



