332 



SCIENCE OF GARDENING. 



PART It. 



some nicety is required in the arrangement and formation of the machinery ; but it is only neteSsary to 

 view the operation in Messrs. Loddiges' house, to be convinced of the extreme advantage and utility of 

 the invention, when it is properly executed. (Shbine, m Hort. Trans, vol. iii. p. 15.) We adopted this plan 

 on a smaller scale in our erections at Bayswater, and the whole of the plants under the square dome 

 (in fig. 253.) were watered from a perforated pipe, which passed round the dome near its apex, and radiated 

 from thence a very fine shower, which reached every part of the floor beneath. 



1690. Wind in hot-houses has been attempted, or rather recommended to be attempted, 

 by Dr. Anderson and others by means of fans. If any thing of this sort were desirable, 

 the Eolian machine invented by B. Deacon, already mentioned (1599.) might be 

 employed, either placed in the house, and kept in motion by human, or mechanical 

 power, or placed at one end to force in or draw out the air. In a range of houses form- 

 ing a circle or square, or any endless figure, a perpetual breeze might be readily 

 produced in the following manner. Place under the floor, a powerful fan of the width 

 of the house. Exactly over the fan, place a glass division across the house, and let the 

 fan draw in the air through apertures in the floor on one side of the division, and give it 

 out through similar apertures, or through tubes of any sort on the other. It is evident, 

 a regular current would thus be produced, more or less powerful according to the size of 

 the fan, and the rapidity of its motion. 



1691. Ventilators, $c. The general mode of renewing the air, is by opening the 

 sashes or doors of the house, in periods when the exterior temperature and weather is such 

 as not to injure the plants within. The cool air of the atmosphere being then more 

 dense than that of the house, rushes in till it cools down the air of the house nearly to an 

 equilibrium with that without. The next mode most common, is that of having a range 

 of boards hinged to oblong openings, in the lower and upper parts of the house, and 

 generally in the front and back wall : those in the back wall opening to the south, or 

 having the opening otherwise guarded, so as to prevent the rushing in of cold north 

 winds. Sometimes these ventilators are made with a cylinder and fans to extract the air, 

 and sometimes, as most generally, they are mere openings of small dimensions ; but, in 

 order to effect any circulation or renewal with this sort of ventilators, the opening must 

 have an area of two or three feet, and there must be a considerable difference of temperature 

 between the air of the house and the open air. 



1692. To effect the renewal, or cooling doivn the air, without manual labor, some con- 

 trivances have been adopted besides the automaton gardener of Kewley already described. 

 (Jig. 217.) Dr. Anderson and J. Williams made use of oblong bladders made fast at 

 one end, and with the other attached by means of a cord to a moveable pane or small 

 sash. The bladder being filled with air at the common temperature allowed for the 

 house, and hermetically sealed, the window remains at rest ; but as the air of the house 

 becomes heated, so does that of the bladder, which consequently swells, and assumes the 

 globular form, its peripheries are brought nearer together, and of course the sash or pane 

 pulled inwards. In a small house this scheme may answer perfectly well for the pre- 

 vention of extreme heat. Another mode is by using a rod of metal, such as lead, of 

 the whole length of the house, and one end being fixed to the wall, on the other is 

 attached a series of multiplying wheels, the last of which works into one, which in 

 various ways may open valves or sashes. As the expansion of lead is considerable, the 

 effect of twenty degrees of increase with proper machinery, might perhaps guard against 

 extremes, as in the other case. A column of mercury , with a piston-rod and machinery 

 attached, has also been used, and a ring on a barometrical principle is suggested by 

 Silvester; but the only complete mode is that of Kewley. For details at greater length 

 on all the departments of the construction of hot-houses, see Remarks, &c. 4to. 1817. 



SECT. IV, Mushroom-houses. 



1693. The mushroom-house is a genus of plant-habitation, which differs from the others 

 in requiring very little light. The simplest form of the mushroom-house is that of an 

 open shed or roof, supported on props, for throwing off the rain, and protecting from per- 

 pendicular cold. Under this, the mushrooms are grown on ridges, covered by straw, &c. 

 to maintain the requisite temperature. 



1694. The Jlued mushroom-house (Jig. 278.) is an improvement on the shed, by being 

 better calculated for growing them in winter. Provided it be placed in a dry situation, 

 the aspect, size, proportions, doors, or windows, are of little consequence. To be suffi- 



278 



