316 PROTECTION OF PLANT-HOUSES DURING COLD NIGHTS. 



destroyed. Peaches and other fruit trees might frequently be 

 protected in this way, and the crop, at least, partly saved, instead 

 of being, in one single night, blasted for the season. 



Common bass mats afford the best and cheapest protection for 

 frames and small pits; but they have the fault of absorbing 

 moisture very readily in wet weather, and then become very bad 

 protection. They should never be laid on the glass in a wet 

 state, as they are sure to do more injury than good. We have 

 found it an excellent method, in covering frames and small 

 houses with mats, to have a thin water-proof covering to lay 

 over the mats, which not only prevents the escape of the con- 

 fined air, but also keeps the mats always dry, and thus, one of 

 the very best protectors is obtained. 



Large structures are more difficult to cover than pits, and the 

 difficulty which thus presents itself has, in general, prevented 

 every attempt to overcome it. We have seen various plans put 

 in operation, besides that which we have already described ; all 

 more or less effectual. The difficulty of getting common rollers 

 to work in frosty weather has made them all but useless, in the 

 protection of hot-houses by rolling blinds, or screens of oil-cloth. 

 Nevertheless, this plan is not only an effectual one, but one 

 which is cheap and easily adopted. And the cloth can be drawn 

 off, in the mornings, and spread out to dry on the snow, or hung 

 on a fence, during the day. When the time comes for covering 

 at night, it might be so arranged as to be drawn up by cords 

 passing through a pulley at each end of the house. We have 

 succeeded in arrangements of this kind ; and the saving of fuel 

 in a severe winter, with the certainty of the plants, being safe 

 from injury, either from frost or from fire, is ample compensation 

 for the trouble which it costs. 



Whatever kind of object it is wished to protect, whether a 

 house or a plant, the protector should always be at least one 

 foot from it. A considerable difference of temperature is always 

 observed, on still and serene nights, between bodies sheltered 

 from the sky by substances touching them, and similar bodies 

 which were sheltered by a substance a little above them. "I 

 found, for example," says Dr. Wells, " upon one night, that the 

 warmth of grass sheltered by a cambric handkerchief, raised a 



