712 Summary View of the Progress of Gardening, 



is only a few inches in width, containing the water to be heated, 

 and communicating with the pipes in which the circulation is 

 carried on. The hollow cone in the centre may be either wholly 

 or partially filled with coke, cinders, or any kind of coal that 

 will not cake, and the fire so made will continue to burn slowly 

 for many hours, without any attention on the part of the gar- 

 dener. This boiler costs little compared with others, is not 

 liable to go out of repair, and it may be set by any common 

 bricklayer. It is not, however, adapted for extensive concerns 

 where much heat requires to be generated in a short time. For 

 all such cases, fireplaces in which the fuel can be readily and 

 frequently stirred and added to are essential. The flattened 

 crown glass mentioned in p. 614. as being used at Chatsworth, 

 and in the Horticultural Society's Garden, and as being equally 

 clear as, and much stronger than, crown glass, and not much 

 dearer, and at the same time capable of being used in panes 40 in. 

 in length, promises to come into general use in plant structures. 

 Had this glass not been lately brought into use, it is not impro- 

 bable that plate glass would have been employed for the roofs 

 of conservatories where the panes are large, as in the end it is 

 found more economical than crown glass ; which, when in large 

 panes, is liable to be broken by hail in summer, and by water 

 freezing between the laps in winter. An elegant and economical 

 trellis for fruit trees, by Mr. Booth, is described in detail in 

 p. 632., and, when known, we have little doubt of its coming 

 into general use. This kind of trellis is equally eligible as an 

 invisible fence in pleasure-grounds, and for this purpose we have 

 lately had it put up without any stay-bars above ground ; a 

 mode readily effected by means of cross pieces of stone or of 

 wood sunk beneath the surface. An excellent fence of this 

 kind has been put up by Mr. Porter of Thames Street, as a 

 boundary to the lawn of the Holme, the elegant villa of J. An- 

 derson, Esq., in the Regent's Park ; and, though there is a part 

 of this fence very much curved, there is not a single stay-bar to 

 be seen from one end to the other. As far as we are aware, it 

 is the first curved invisible wire fence that has been put up 

 without a visible stay-bar ; and we most strongly recommend this 

 mode to be adopted on every occasion. A light folding-ladder 

 (p. 56.), a new kind of wire netting (p. 222.), a propagating 

 box (p. 21.), various modes of forming garden tallies and 

 labels (p. 542.), an earwig trap for dahlias, a pot for orchideous 

 plants, an underground water-holder, a new boiler for heating 

 by hot water, and various other agents, will be found by reference 

 to the contents of our Miscellaneous Intelligence (p. vi.), and 

 deserve the attentive examination of the practical gardener. 



In Plant Structures we would direct attention to Mr. Paxton's 

 mode of constructing hot-houses on the ridge-and-furrow prin- 



