and Forcing' Depaj-tment at Syon. 51 1 



walls, to exclude the frost from the blossom and the birds or 

 flies from the ripe fruit, and also in the covering of flower-beds, 

 hay-ricks, harvested corn, temporary structures for public as- 

 semblages, &c. 



The length of these rolls at Syon is between 50 and 60 ft. 

 but we have no doubt they might be made longer, since this 

 depends on the diameter of the pole or rod {Jig. 101. a), and 

 the toughness of the timber employed, or its power to resist 

 torsion. On one end of this rod and not on both, as is usual, 

 a ratchet wheel [b) is fixed, with a plate against it (r) so as to 

 form a pulley groove between [d), to which a cord is fastened, 

 and about 3 in. further on the rod is fixed a third iron wheel, 

 about 6 in. in diameter and half an inch thick (e). This last 

 wheel runs in an iron groove {f), which extends along the 

 end rafter or end v/all of the roof to be covered. The can- 

 vass or netting being sewed together of a sufficient size to 

 cover the roof, one side of it is nailed to a slip of wood placed 

 against the back wall, that is, along the upper ends of the 

 sashes ; the other side is nailed to the rotl {a). When the 

 canvass is rolled up, it is held in its place under a coping {g) 

 by a ratchet (//), and when it is to be let down, the cord (/) 

 of the roll is loosened with one hand and the ratchet cord [k) 

 pulled with the other, when the canvass unrolls with its own 

 weight. The process of pulling it up again need not be de- 

 scribed. The most valuable part of the plan is, that the roll 

 of canvass, throughout its whole length, winds up and lets 

 down without a single wrinkle, notwithstanding the pulley- 

 wheel is only on one end. This is owing to the weight 

 of the rod, and its equal diametei' throughout. By this plan 

 a house 100 or 150 ft. long, might be covered with two rolls, 

 the two pulleys working at the two ends ; but if it were 

 thought necessary, the two rods might be joined in the mid- 

 dle, and, by a little contrivance, the pulley and groove placed 

 there, so as to w^ork both of the rolls at once, from the inside 

 of the house, from the back shed, or from the front. A more 

 beautiful contrivance, for the purpose to which it is applied, 

 we will venture to assert, is no where to be met with. It was 

 constructed under Mr. Forrest's direction by Mr. Boughton, 

 smith, Brentford End. 



Such are the improvements that the Duke of Northumber- 

 land has made in his kitchen-garden at Syon ; and it is im- 

 portant to remark that so promptly and judiciously were all 

 the measures taken for their execution and so rapidly was that 

 execution proceeded with, that in eight months after the work 

 was commenced the whole was completed; the houses, bor- 

 ders, and walls were planted; the compartments cropped; the 



