306 Memoirs of the Caledonian Horticultural Society. 



whole apparatus, by being moved upwards or downwards, 

 from socket to socket by the hand, according to the various 

 degrees of air-vent wanted. This iron pin is fixed to a cord 

 or chain (c), passing through the style (a), over a pulley (d), 

 which cord or chain is fixed to a rod or chain (e e), having an 

 axle joint at the junction of each lever. The rod or chain, 

 when the hand-pin (b) is moved up or down, moves horizontally 

 between a pulley (d), and another pulley (/), fixed to the cor- 

 responding style at the other end of the house, by the action of 

 a weight (g), attached to the end of the rod by a cord or 

 chain passing over the second pulley (/). This horizontal rod 

 or chain (e e), in its motion, thus produced by a weight (g), 

 operates at every joint, as already mentioned, on bent le- 

 vers (k% which, being attached to hatches (&), lift them or 

 lower them so as to admit or exclude the air, as circumstances 

 may require. The upper end of the lever is fastened to the 

 hatches by screw-nuts, in order that, by unscrewing them, the 

 sashes may be freed from the levers, and removed at pleasure 

 for repair. The hatches occupy the place of two, three, or 

 four panes lengthwise at the top of the sash, proportioned to 

 the dimensions of the house, and are hinged upon one of the 

 astragals, projecting both at the sides and the ends, to exclude 

 the wet." 



In various descriptions of hot-houses, this mode of ventila- 

 ting may be found worth adopting ; it will certainly be found 

 cheaper than sliding sashes, and air may be given or taken 

 away in far less time ; but a still better mode of ventilation is 

 that of Mr. Atkinson already described. (Vol. II. p. 200.) One 

 advantage of Mr. Tweedie's plan is, that it may be applied 

 with facility to hot-houses already existing; but where new 

 houses are to be built, we should decidedly prefer Mr. At- 

 kinson's to every other. 



9. Queries relative to the Soloing, instead of Planting, of Forest 

 Trees. By Messrs. Bishop, Beattie, and Mitchell. 



Some speculations on the taproot, and the danger of de- 

 stroying it in transplanting forest trees, which appeared in 

 the Caledonian Society's Memoirs (vol. ii. p. 416), and which 

 these three gardeners, who rank among the most intelligent 

 and experienced in Scotland, consider as " strange lights apt 

 to mislead the unwary," have led to these queries, which are 

 as follows : — 



" 1. Has it been ascertained by accurate experiments, that 

 the taproots in timber trees have a general tendency to pro- 



