150 



HEATING AS APPLIED IN HORTICULTURE. 



and, for straight lines of flues, are of two 

 moulds only, as a and b on the annexed 

 fig. 157 will show. With two additional 

 moulds to give the necessary bevels, bricks 

 can be made to suit any direction the flue 

 may take. Were it not for the patent, 

 such bricks could be made by any brick- 

 maker, and at little more cost than those 

 of ordinary shape. 



The advantage of circular flues, over all 

 other forms, is their securing a greater 

 uniformity of draught. We would, how- 

 ever, have moulded the bricks so as to 

 have shown a cylindrical form externally 

 — a form certainly more agreeable to the 

 eye than that of any of the forms in 

 general use. 



We have elsewhere stated that smoke 

 flues have one advantage over steam or 

 hot-water heating — namely, the power of 

 throwing heat into a hothouse or green- 

 house in much less time, and hence of re- 

 pelling sudden frosts in the latter structure 

 in particular. Steam cannot be generated 

 speedily; and, from the best authorities, 

 we find that a hot-water apparatus, how- 

 ever well constructed, is liable to the 

 same defect, as it is proved that it will 

 take as many hours to acquire a tempera- 

 ture of 200° as the pipes are inches in 

 diameter, and it will also cool in the same 

 ratio. For example, the water in a 4-inch 

 pipe will take four hours to arrive at that 

 temperature : it may, indeed, be heated to 

 that point in one hour if the apparatus is 

 properly constructed, but to effect this, 

 four times the quantity of fuel will 

 be consumed that would be sufficient if 

 properly applied; and if we take into 

 consideration the extra waste of heat at 

 the chimney-top, which, under such cir- 

 cumstances, increases very rapidly, we 

 may safely set it down at five or six times 

 the quantity of fuel consumed unneces- 

 sarily. The economy of fuel ought always 

 to be considered in every mode of heating; 

 and we are confident that one-sixth of the 

 quantity would suffice for a greenhouse 

 heated with a good flue, to what would be 

 consumed under the above circumstances. 



One of the most frequent complaints 

 made against the use of smoke flues is 

 the inconvenience, not to say anything 

 of the dirt and disorder, attending the 

 process of cleaning them. This may, 

 however, in a great measure be got rid 

 of by having cast-iron frames provided 



with flange covers made to fit accurately, 

 and placed on the top, or in the side of the 

 flues at convenient distances. Two rings 

 are fixed to these covers, so that they may 

 be easily lifted up to enable a labourer to 

 extract the soot in the regular way. Here 

 we may, however, observe that the soot 

 should be wetted as it is drawn to the 

 opening, which will prevent its flying 

 about the house. These metallic covers 

 may be so formed as to act as evaporat- 

 ing pans to restore that humidity to the 

 atmosphere, of which all modes of heating 

 have greater or less tendency to deprive 

 it, and of which it is naturally possessed. 



Mr Saul of Lancaster has suggested — 

 and we know that the idea has been 

 acted upon in a most satisfactory man- 

 ner — to build rollers on all the salient 

 angles of the flues, and one at the top of 

 the upright chimney; over the end of 

 this and the rest of the rollers a conduct- 

 ing endless chain passes, to any part of 

 which a brush is fixed, which, by being 

 drawn backwards and forwards, cleans 

 the flue of soot. It is, however, necessary 

 in this case to have a door made at the 

 bottom of the chimney, through which 

 access may be got to the chain, and by 

 which the soot may be extracted. Of 

 course, the chain is a fixture, and remains 

 always in the flue. This is upon the 

 same principle recommended by Mr Lyon 

 for sweeping house chimneys, to prevent 

 the inhuman practice of sending children 

 up — a practice it would be difficult to find 

 the origin of, and which has been very 

 wisely prohibited by our Legislature. 



A prejudice has arisen against smoke 

 flues, from the carelessness of those hav- 

 ing the management of them in not 

 attending to keep them clear of soot. So 

 long as the flue draws, and the smoke 

 finds its way out at the chimney-top, all is 

 allowed to go on without regard to the 

 vast unnecessary consumption of fuel in 

 consequence of the flue being coated with 

 soot, which is of itself one of the greatest 

 non-conductors of heat, and is, in fact, 

 charcoal in a more completely burned 

 state. We know that gardeners often 

 delay cleaning their flues, because by the 

 usual method bricklayers are required to 

 open them up and to rebuild them, which 

 operation costs money and creates dirt 

 and confusion. By adopting the flue recom- 

 mended above, the first of these will be 



