Transactions of the Horticultural Society. 



419 



every garden, but in every dwelling-house, and ship. Besides 

 garden purposes, it may be used as a forcing pump, sucking 

 pump, for giving enemas either in surgical or veterinary prac- 

 tice ; for relieving hoven cattle ; for extracting poison from the 

 stomach ; for injections of different kinds ; for annoying an 

 enemy or dispelling a mob by the discharge of offensive 

 liquids ; and for extinguishing fires. Mr. R. has published a 

 pamphlet on its various uses. 



14. Description of a self-acting Ventilator for Hot-houses. By 

 John Williams, Esq. C.M.H.S., of Pitmaston. Read April 6. 

 1824. 



The intention of this ventilator is to guard against extremes 

 in the absence of the gardener. It is effected by the expansion 

 and contraction of air in an air-tight vessel {fig. 85. a), com- 

 municating with a cylinder and 

 piston {b, c, d), which, by means 

 of a rod (g), operates on the 

 ventilator, or sash, to be opened. 

 The use of the water, or other 

 fluid, is to confine the air, and 

 by that means, when the air ex- 

 pands or contracts, it operates 

 upon the piston. By means of 

 an adjusting screw (/"), the 

 register may be made to open at 

 any required degree of heat. The 

 air-vessel {a) should contain 

 several gallons, according to 

 the size of the valve, or register, 

 to be opened. When first used, 

 the vessel must be heated suf- 

 ficiently to expand the internal 

 air ; water is then to be poured 

 in at the top of the cylinder (e), 

 so as to give the required motion 

 to the float ; and about half an 

 inch of fine oil must be laid on 

 the top of the water (at c) to 

 prevent evaporation. 



" The vessel must be placed in front ot the upper part of the 

 back wall, and at all times fully exposed to the light. If the 

 apparatus is of proper size, nicely constructed, and filled with a 

 proper quantity of water, the registers, one being placed in the 

 upper part of the back wall for the escape of the heated air, and 



