Birmingham Botanical Horticultural Garden. 421 



part a supply cistern for the hot-houses and jets. Round the base there 

 is a vaulted passage, by which carts may pass round, unless it is consi- 

 dered preferable to ascend the inclined plane h, and drop the coals, 

 through man-holes on the surface, to the cellars below. 



h, Inclined plane to the tunnel. 



i, Tunnel, which communicates with the base of the tower, the interior 

 area, and the public road. 



k, Mains of the steam or hot-water apparatus. 



The section, which is taken across an imaginary line from 

 i, through g and Ic, to a, exhibits the following details : — 



1 1, Exterior pits. m m, Interior pits. n, Tunnel. 



o, Archway, forming the entrance to the inclined plane which leads from 

 the tunnel to the surface of the central area. 



f) p, Two steam or hot-water apparatus : either of these will supply heat 

 to the whole range ; but two are recommended, in case of accident. 



q, Potting-shed. r, Cistern. 



s s, Walks within the hot-houses. 



t, Walk over them, in which, during winter, rolls of matting may be kept, 

 for letting down over the glass to exclude the frost. 



u u u u, Situation of pipes pierced with numerous small holes, for wa- 

 tering all the hot-houses, in imitation of a shower of rain, as at Messrs. 

 Loddiges's. 



v, Steam-pipes shown under the pathways. 



w ww w, Benches for pots. 



x x, Surface of the terrace walk. 



y z, Elevation, taken opposite the centre of either of the four entrances. 



The cheapest and best mode of heating these hot-houses, 

 we think, will be by steam : cheapest, because, by this method, 

 they can be better heated from one common apparatus than 

 they could by hot water ; and best, because the supply of heat 

 by steam can be more rapidly withdrawn than either by hot 

 water or smoke flues. It is true, excessive heat can always 

 be reduced by the admission of air, and by watering; but it 

 is not desirable, in point of economy, as well as for other 

 reasons, that such an excess should be produced. As the 

 simplest mode of conducting the steam, we would suggest 

 carrying it out by main pipes and branch pipes, all sloping 

 from the apparatus, with returning branch pipes and mains 

 for the condensed water, all having an inclination to the 

 apparatus. There ought to be two steam-boilers, each of di- 

 mensions to heat the whole structure, and each connected with 

 the same main tubes ; so that, if at any time one of them 

 were out of order, the other might instantly be set to work. 

 Under the pathways there might be cast-iron cisterns in 

 different places, to receive the rain water from the roof; and 

 these cisterns might be heated by the steam-pipes. At the 

 same time, the water in the central cistern over the steam 

 apparatus will never be very cold, and might easily be raised 

 to a sufficient temperature for immediate use in the hot-houses, 

 by the introduction of steam from a pipe below, 



E e 3 



