By John Frederic Daniell, Esq. 13 



so trained, the absolute perpendicular impression could have 

 little effect, and this little might even be prevented by a 

 moderate coping, 



Mats or canvass, upon rollers to draw down occasionally in 

 front of the trees, at the distance of a foot or two from their 

 foliage, would, I have no doubt, be a great advantage in 

 certain dry states of the atmosphere before alluded to, and 

 in the case of walls which are not opposed to others, would 

 be a good substitute for the protection of the latter. 



Experience has taught gardeners the advantages^ warding 

 off the effects of frost from tender vegetables, by loose straw 

 or other litter, but the system of matting does not appear to 

 be carried to that extent which its simplicity and efficacy 

 would suggest. Neither does the manner of fixing the 

 screen exhibit a proper acquaintance with the principle upon 

 which it is resorted to : it is generally bound tight round the 

 tree which it is required to protect, or nailed in close contact 

 with its foliage. 



Now it should be borne in mind, that the radiation is only 

 transferred from the tree to the mat, and the cold of the 

 latter will be conducted to the former in every point where 

 it touches. Contact should therefore be prevented by hoops 

 or other means properly applied, and the stratum of air 

 which is enclosed will by its low conducting power effectually 

 secure the plant. With their foliage thus protected, and 

 their roots well covered with litter, many evergreens might 

 doubtless be brought to survive the rigour of our winters, 

 which are now confined to the stunted growth of the green 

 house and conservatory. 



The secondary effect which radiation has upon the climate 



