168 



JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 



[ August 29, 1872. 



iron is to be cooled down by the rapid circulation of air ; at 

 least, this seems to be the principle on which Mr. Housman 

 depends upon for extracting the heat from the stOTe. Now, 

 air is such a bad conductor of heat that it would never extract 

 enough heat from the iron to keep it at a low temperature ; 

 and although currents of moistened air are capable of conduct- 

 ing and extracting more heat than dry, yet it is impossible to 

 get cold outer air completely saturated with moisture merely 

 by evaporating pans, and there must always be a great waste 

 of heat to have to heat the iron envelope by means of a 

 thickness of brick, though, no doubt, the brick acts its part in 

 storing up heat after the fire is out. 



In his description of the circulation of air in his model 

 houses, Mr. Housman seems to forget how rapidly air parts 

 with its heat by evaporation, and that on a clear winter's 

 night not only would the moistened heated air part with its 

 moisture and be condensed as it rose against the top glass ; 

 but it would cool so rapidly and lose so much of its volume by 

 contraction, that I should be very sorry to have to rely on his 

 currents of air to keep out frost from the third house. 



Mr. Housman says in page 111, " I dismiss the flue at once. 

 If made secure it is costly, and dangerous even then, exigent of 

 supplies of moisture, and utterly incapable of adaptation to 

 varying wants." Now, I do not want to advocate a flue against 

 hot water, but as far as moisture is concerned it is just as easy 

 to supply a sufficiency of moisture by means of a flue as by 

 means of hot air, and I do not think the flue is to be dismissed 

 so easily ; nor do I agree with the dictum that heat required 

 for draught is not available for heating purposes. There is no 

 real economy of fuel in a tall shaft, it only insures more per- 

 fect combustion ; and the reason why a taU chimney may be 

 cold and a short one hot, is that there is a greater rapidity of 

 draught through the taller chimney, so that the products of 

 combustion pass more quickly through it ; but if we want 

 economy of heating power we require slow combustion and a 

 slow draught. It is in this point that a properly constructed 

 horticultural boiler is pre-eminently successful in extracting 

 the maximum of heat from the fuel consumed — that the pro- 

 ducts of combustion coming directly in contact with the com- 

 paratively cool surface of the boiler have their heat extracted 

 by the conducting power of the iron and water, the iron being 

 kept cool by the water, and the greater the difference between 

 the temperature of the iron and of the heated currents of air 

 that impinge upon it the more rapidly it conducts the heat or 

 extracts the heat from the products of combustion. 



Mr. Housman ends, " It seems almost superfluous to observe 

 that a stove of this kind, standing free in a shaft, and for ever 

 swept by rapid currents of air, must yield up more heat than a 

 boiler bedded in masonry." Here I totally differ in opinion 

 from him. First of all, a boiler should not be bedded in ma- 

 sonry, but should have a flue all round it ; and, secondly, just 

 in proportion as air is a worse conductor of heat than water, 

 so is the surface of the stove less liable to be cooled down by 

 the air than the water. If Mr. Housman's giU stove were sur- 

 rounded by a water-jacket, it would extract far more heat than 

 by any method of currents of heated air, especiaUy as the 

 rapidity is rather imaginary, being solely dependant on the 

 fact that as air is heated it rises, but the rapidity with which 

 it rises entirely depends on the amount of heat it extracts from 

 the stove. And lastly, Mr. Housman says, " Seeing how often 

 hot-water pipes are for the sake of appearance sunk in flues 

 beneath the floor, there seems to be no valid reason why such 

 flues should not be used without the pipes." Now, though 

 hot-water pipes are very often put into flues, yet it is entirely 

 wrong to do so. Many persons overlook the primary law of 

 heat, " that heat radiates equally in every direction," by 

 thinking too much of the second — that is, " that heated fluids 

 rise." An immense amount of heat is wasted where pipes are 

 put under the floor in flues, by the heat which is absorbed by 

 the flues themselves ; and the same would be equally true 

 where hot air is made to pass far through flues, especially flues 

 with evaporating troughs, by which a great deal of heat would be 

 absorbed. Mr. Housman must pardon me if in accepting his 

 challenge to discuss the comparative merits of hot air and hot 

 water I have expressed my opinions too freely. — Toue Repoetee. 



of being a series of horizontally revolving blades, is composed 

 of a set of radiating blades revolving vertically. The machine 

 is propelled in the same manner as the lawn- 

 mower, and with the same ease ; but more 

 caution is necessary, from the importance of 

 being obliged to direct it in straight lines or 

 round curves corresponding with the edges of 

 the turf to be cut. 



In large establishments, where there is a 

 great extent of turf edgings, the adoption of 

 this implement will be of incalculable service. 

 The ordinary method of trimming with edging- 

 shears is, as everyone knows, a long and slow 

 process ; but with the turf-edger the work is 

 performed with as great rapidity as a lawn- 

 mower is propelled. We have ourselves used 

 the machine, and there- 

 fore speak of it experi- 

 mentally, from which we 

 learn two things : the 

 turf edgings must be 

 level and even, as all 

 good edgings ought to 

 be. If otherwise, the 

 revolving blades are apt 

 to become clogged by 

 protruding pieces of 

 turf ; and as it is not 

 turf the machine is intended to cut, but the overgrown grass, 

 it is necessary that the edgings be even. The second caution 

 is not to rush heedlessly in using the instrument, but to 

 practise it with caution, till by a little experience the hand and 

 the eye have been accustomed to direct the machine just to 

 trim the grass, and no more. 



We can strongly recommend Mr. Townsend's machine as 

 being effective in execution, and a marvellous saving of labour, 

 which in these days is an important consideration. 



PORTRAITS OF PLANTS, FLOWERS, 

 FRUITS. 



AND 



TOWNSEND'S TURF-EDGER, 

 As an adjunct to the lawn-mower, we know of none more 

 valuable and useful than the turf-edger invented and intro- 

 duced by Mr. Townsend, of Wimbish. In appearance it is 

 exactly like the lawn-mower, but the cutting appliance, instead 



XiPHiror TiNGiT-ixrii (Tangier Xiphion). Nat. ord. , Iridacea?. 

 Linn., Triandria Monogynia. — This magnificent Iris was dis- 

 covered by Salzmann in 1S25 , in meadows near Tangier. Its 

 flowers are pinkish-purple. Dr. Hooker says — " During my 

 late visit to Marocco with Messrs. Ball and Maw, we first saw 

 Iris tiugitana on the dinner-table of His Excellency Sir J. Hay, 

 at Tangier, where it was a most striking object. The speci- 

 mens were from his garden, and we were informed that it was 

 found wild not nearer than ten miles south-west of Tangier, 

 near Laraisch. Thither one of our party (Mr. Maw) made 

 two excursions, the first one in vain, but the second with suc- 

 cess. Specimens, both from this source and from Sir -J. Hay's 

 garden, were sent to Eew, which flowered in May of the 

 present year." — (Bot. Mag., t. 5981.) 



Muxtixgia Calabuea. Nat. ord., Tiliaeeae. Linn., Poly- 

 andria Monogynia. — Flowers white. A handsome stove shrub. 

 Native of New Grenada.— {Ibid., t. 59S2.) 



Lixaeia AtAKOcciXA (Marocco Antirrhinum). Nat. ord. r 

 Scrophulariacea. Linn., Didynamia Angiospermia. — Flowers 

 pinkish-purple. Dr. Hooker discovered it last year, and thus 

 notices it — " During my excursion to that country with Messrs. 

 Maw and Ball, we collected no less than twenty species of this 

 genus, amongst which the subject of the present plate was 

 conspicuous in one district for its abundance and brilliant 

 colour, adorning the cornfields in profusion in the province of 

 Sectana, which skirts the greater Atlas in lat. 31° N. L. ma- 

 roccana belongs to a large section of the genus, and is closely 

 allied to L. reticulata, Desf., of Portugal and N. Marocco. The 

 seeds brought home germinated freely and flowered in the 

 Royal Gardens in June of the present year." — {Ibid., t. 5983.) 



Gaultheeia feageaxtissima (Most Fragrant Gaultheria). 

 Nat. ord., Ericaceae. Linn., Dec'andria Monogynia. — An ever- 

 green greenhouse shrub, with white very fragrant flowers. 

 Native of the Himalayan and Nilgherry Mountains. Dr. 

 Hooker says — " It should prove a greater favourite than 

 Clethra arborea, which it somewhat resembles in general 

 effect, from its profuse flowering. The specimen here figured 

 flowered with I. A. Henry, Esq., in April, 1869, and was con- 

 siderately communicated to us for figuring." — {Ibid., t., 5984). 



ZAinocuLCAs Loddigesii (Loddiges' Zamioculcas). Nat. ord., 

 Aroideae. Linn., Moncecia Polyandria. — About fifty yeais 



