550 



THE PRACTICAL GARDENER. 



ones the heated air, being more hglit, readily escapes, and 

 tlie space emptied by such air escaping is immediately filled 

 ^vith fresh air from below, which circulates through the house, 

 until it becomes sufficiently heated to find its way out. This 

 important improvement in the necessary change of air in hot- 

 houses was first brought into notice by W. Atkinson, Esq., and 

 has been employed, with every success, in the numerous hot- 

 houses built under the direction of that gentleman. The cold 

 air passing into houses in this manner, having to pass over the 

 flue immediately upon entering the house, becomes moderated 

 in temperature, so that it cannot possibly injure the most deli- 

 cate bud or flower ; while the methods formerly in use pos- 

 sessed this defect, that the necessary fresh air, however cold 

 it might be, was let in close upon the trees by opening the 

 sashes, .and while the tree was warm within. Thus a number 

 of currents of cold air were in an instant let in upon them, 

 which could not but prove of much injury to them in their more 

 tender state. Nothing is so injurious to vegetables, as well as 

 to animals, as sudden transitions from excessive heat to exces- 

 sive cold. For early forcing, this mode of ventilating is de- 

 cidedly the best, and all houses, whether for early ov late 

 crops, should be provided with such ventilators, thereby af- 

 fording the means of giving air in cold or wet weather, when 

 it could not be with safety admitted by the roof-sashes. 



FOOTPATHS. 



Footpaths have hitherto most generally been composed of 

 mere planks, laid upon the borders to walk on ; in other cases, 

 lattice-work has been adopted, supported on blocks of wood, in 

 order to admit the sun and air to the border below, and to 

 prevent its being much trodden on by walking. Neat wooden 

 footpaths, painted and elevated two or three inches above the 

 border, arc not objectionable ; but the neatest and most per- 

 manent are constructed of cast-iron plates, made to rest upon 

 props, at a proper height from the ground. These cast-iron 

 gratings can be made to any pattern, and of lengths convenient 



