MATS FOR COVERING PITS AND FRAMES. 



569 



of very rough wood; are narrow — not exceeding 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, 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 j> 10 . 322. 



lost, and when the 



frames are covered by 



the neat, warm, and 



flexible straw mats, 



they are as snug as 



could be desired. 



When it is simply 



desired to preserve 



the spaces between 



Narrow frames used for forcing by the market 

 gardeners of Paris. 



bedding plants through the winter, 

 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 tor 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 



