444 



PITS AND FRAMES. 



The inventor of this pit remarks, that 

 objections may be made to his plan, as, 

 " that the ascending flues should be at 

 the front rather than at the back, lest 

 the upper part of the pit should be 

 warmer than the front. The extreme 

 rapidity of the circulation already alluded 

 to is a complete answer to this objec- 

 tion ; but further, any other arrange- 

 ment of the circulation than that above 

 suggested would be prejudicial, and lead 

 to precisely the opposite results to those 

 intended. In the first place, instead of 

 a great, there should be but a small 

 difference between the ascending and 

 descending columns, and consequently a 

 much slower circulation. In the next 

 place, if the descending flues were at the 

 bottom of the back instead of at the front, 

 and the heated air entered at the front, 

 it would immediately rise to the upper 

 part of the pit, and there accumulate its 

 heat, while the whole surface occupied by 

 the plants would be covered by the 

 coldest air. Moreover, the earth at the 

 back being always higher than the front, 

 the coldest air would not flow away to be 

 repeated, but would lie all along the 

 front of the pit, and scarcely circulate at 

 all; whereas, by the arrangement pro- 

 posed, the coldest air will always descend 

 to be heated, while the influx of warm 

 air, constantly encountering the warmest 

 air, which has risen to the top, will beat 

 it down, and mingle it with that below. 

 This is perhaps theory, but it is theory 

 based on experience; and I have no 

 hesitation," he says, " in saying that such 

 would be the effects." 



Glendinning' 's pit, heated according to 

 Mr Corbet? s system. — The pit of which 

 fig. 618 is a cross section was designed 



by Mr Glendinning, of Chiswick, to whose 

 taste and judgment in all that relates to 



garden architecture we have more than 

 once alluded in the foregoing pages. The 

 plan of this pit was, we are informed by 

 Mr Glendinning, in " Gardeners' Maga- 

 zine," vol. xvii. p. 58, made out for His 

 Grace the Duke of Somerset. The plan 

 is so clear that we need not attempt its 

 description, farther than by giving the 

 note of reference accompanying the origi- 

 nal plan. " a a, glass roof; b, bark pit ; 

 c, back path ; d, pit for dung lining ; e, 

 drain ; /, hinged cover of ledgered boards 

 to protect the dung from the rain and 

 wind ; g, ground-line ; h, suspended shelf 

 for strawberries in pots ; i, slate shelf for 

 pots; k, stink-trap communicating with 

 the cross-drain, I, which leads to main 

 drain ; m, Corbett's hot-water apparatus ; 

 n, hollow wall of bricks on edge." This 

 will be seen at a glance to be a pit of 

 great merit and utility. The linings of 

 dung in front will not only throw in heat, 

 but also that genial and invigorating kind 

 of atmosphere in which the inmates of 

 all pits seem to delight ; and much as we 

 could wish to see dung applied to the 

 enrichment of the soil — its real and legi- 

 timate use — still we are not blind to its 

 great utility in its application to forcing 

 purposes. As the back part of the roof 

 is glazed, we think the introduction of 

 shelves under it good, as they in no way 

 interfere with the plants in the main bed. 

 The hot-water gutter behind gives out 

 heat in the part generally coldest, and 

 equalises the degree of humidity in all 

 parts of the house. The drainage is 

 efficient ; and we may here remark, that 

 this very important accompaniment is 

 more fully attended to in the designs of 

 Mr Glendinning than in those of any 

 other garden architect — a convincing 

 proof of his practical acquaintance with 

 the subject. 



Mitchell's forcing-pit, figs. 619, 620. — 

 The annexed cuts represent two ranges of 

 pits of a very economic character, erected 

 at Somerton Erleigh by Mr Josiah Mit- 

 chell, from his own designs, with which 

 he has kindly favoured us, accompanied 

 by the following description : " They 

 are heated by hot water, one boiler 

 serving the two pits, and supplying them 

 with both bottom and atmospheric heat. 

 The heat in each pit is regulated to suit 

 circumstances, by slides contained in 

 the stopping-off boxes, marked g in the 



