Februarj 26, 1874. ] 



JOURNAL OF HORTICULTURE AND COTTAGE GARDENER, 



181 



produced about sixty plants. But what is remarkable in each 

 case is that the seedlings are so different from each other ; 

 indeed many of them are so uuUko the parents as to render 

 it quite a matter of dispute whether they could possibly be 

 their progeny. 



My earnest hope is to obtain great improvements by care- 

 fully selecting seed. What I am most anxious for is to get 

 colour, compact and upright growth, fine fohage, and scent as 

 well as size tit for conservatory decoration. 



For example, I have one seedling with the lower petal or lip 

 black, but the petals are very narrow although long, only 

 1 J or 2 hues wide, yet I was pleased with it as a parent ; and 

 to my great delight some two or three weeks after I had another, 

 although not so dark, yet of good shape and compact growth, 

 properties which the other did not possess. Another seedling 

 I have, although small (not larger than Devoniensis), is quite 

 as dark, of upright growth, and as free a bloomer as the old 

 Russian, producing at one time thirty or forty fully expanded 

 ilowers on a very small plant. This would also be an addition 

 to our conservatory decorative plants. 



How beautiful a plant is The Czar or Giant when well grown, 

 even apart from its flowers. I have two of that habit of 

 growth, with very deep green leaves, quite distinct as to the 

 darkness of the foliage, and having large deep blue Ilowers of 

 good shape. They are likely to be useful as parents, at least 

 i have every hope they will prove so. I'riuce Consort also is 

 of very handsome growth, darker green in leaf than The Czar, 

 and of fine upiight growth. This I intended sending out at 

 the close of this year; but the demand for gathesed flowers is 

 50 great that, iastead of doing so, I purpose planting them as 

 well as largo numbers of Victoria liegina. 



I gather from my present experience that there will be a 

 great demand for these flowers in the large cities and towns of 

 the United Kingdom. They have only to be known to be ap- 

 preciated. Even the working classes give them the preference 

 at an advanced price. — (i. Lee. 



HEATING— FUEL.— No. 4. 



The first requisite in a heating apparatus is power, the 

 second efficiency, and the third economy. Power and el'liciency 

 are in a great measure dependant upon the boiler, but all three 

 are to a large extent affected by the mode in which the heat 

 obtained is applied. We communicate heat to a great volume 

 of water, and only permit it to be radiated in the structure to 

 be heated from a small extent of surface. 



Now, a structure heated by hot water is warmed iu propor- 

 tion to the extent and heat of the pipe surface exposed within 

 it. Pipes heating beds, only give heat indirectly to the house, 

 •consequently pipes used for bottom heat are not to be taken 

 dnto account when calculating the amount of piping required 

 •to heat any structure to a given temperature. It is usual to 

 follow Tredgold in calculating the extent of piping required. 

 His rule is " Multiply the cubic feet of air to be heated by the 

 luumber of degrees the house is to be warmed, and the result 

 divided by twice the difference between the temperature of the 

 house and that of the surface of the pipes will be the feet of 

 piping requhed." In using this formula we must bear iu mind 

 that the temperature of the surface of the pipes at their maxi- 

 mum may be 200' or even boiling (212'j, but as a rule are rarely 

 over 180°, which we will adopt as the maximum temperature 

 of hot-water pipes. Let us apply this to a stove under my 

 •care, 30 feet by 2i feet, and containing 5280 cubic feet of air. 

 The maximum from fire heat is 05°, the temperature of the 

 air being 20°, which is 45° of difference. From the 6280 we 

 must deduct 500 cubic feet for a bed which occupies the centre 

 of the house, and we have 4780 cubic feet of air to be heated 

 by artificial means 45°. This, according to Tredgold's rule, 



would therefore be igfi^^f „ -= ^jo" = 935 feet of pipe sur- 

 face at 180°, which is more by 300 feet of piping than required 

 iu actual practice. COO feet of surface at 180° are sufficient 

 to maintain the maximum of G5°, the external air being at 20°. 

 Tredgold, however, affords us data for ascertaining what he 

 terms the cubic feet of air. " To the length of the stove in 

 feet, multiphed by half the greatest vertical height in feet, 

 add lA time the whole area of glass, and also eleven times the 

 number of doors [in feet] ; the sum will be the number of cubic 

 feet to be heated from the temperature of the external air to that 

 of the stove." In the case of the stove, 80 feet multiplied by 8 

 (half the vertical height) = 2-iO ; this added to U time the whole 

 area of glass = 1734, and eleven times the doors (four) or 880, 



will give a sum of 2854 as the cubic feet. Therefore, as per rule 



, 2854 X 45 1284S0 _-^ , i , ■ t • , , 



above, ,„(,— 55 ^-^ = "23ir ~ feet of pipe surface, equivalent 

 to six rows of 4-inch piping aU round the house excepting the 

 two doorways. 



The latter method of calculating the piping required to 

 maintain any temperature desued is very nearly accurate and 

 accords well with practice, but unless Tredgold's method of 

 ascertaining the cubic feet to be heated be adopted the cal- 

 culations are almost twice too high. 



By Hood's method we also obtain an equally erroneous 

 number of feet of surface. Hood's rule is, " Multiply 125 by 

 the difference between the temperature at which the room (or 

 structure) is proposed to be kept, when at its maximum, and 

 the temperature of the external air, and divide this product 

 by the difference between the temperature of the pipes and the 

 proposed temperature of the room ; then the quotient thus 

 obtained, when multiplied by the number of cubic feet of air 

 to be warmed per minute, and this product divided by 222, 

 will give the number of feet in length of pipe 4 inches dia- 

 meter, which will produce the desired effect." This rule ap- 

 plied to the stove would be : — 45°, the difference between the 

 temperature at which the house is to be kept and that of the 

 external air, multiphed by 125 =5025, which divided by the 

 difference (115J between the temperature of the pipes (180°) and 

 the proposed temperature (65 ), will give 48. 'This multiphed 

 by the number of cubic feet of air to be warmed per minute 

 (4780) =229,440, which, divided by 222, will give us the num- 

 ber of feet of 4-inch piping required = 1033, or nearly double 

 what actual practice demands. The rule is appUed to raise 

 the temperature from 20° to 05", which I am convinced is not 

 the proper minimum to calculate from as that of the external 

 air. It would be much better to reckon the external air at 32°, 

 and the temperature of the surface of the pipes 180°, which 

 ought never to be exceeded in plant houses, except in verj 

 severe periods, and the figures would then stand as under;— 

 125 X 33 = 4125 -=-115 = 35 x 4780 = 107,300^-222 = 753 feet of 

 4-inch piping, which is fuUy 153 feet more than in practice is 

 required. 



We should, however, bear in mind that Hood calculates the 

 temperature of the pipes to be 200°, or 12° less than the boil- 

 ing point of water, which is very much too high a degree for 

 the pipes in horticultural structures to be heated for any con- 

 siderable time ; in fact, life-long practice as a gardener con- 

 vinces me that the lower the temperature of the heating sur- 

 face the more congenial is the heat to the growth of plants. 

 Instead of heating pipes to a temperature of 200°, or even 

 160°, I am satisfied the pipe surface should seldom exceed in 

 temperature twice that required to be given any structure to be 

 warmed. This would entail a larger heating surface than would 

 be needed were the heat radiated at a higher temperature ; as, for 

 instance, for the stove aforenamed we at 180' require 753 feet to 

 give a temperature of 05°, calculating the external air at 32° ; but 

 if the temperature of the pipes were 200°, according to Hood we 

 have 125x33 = 4125->135 = 30x4780 = 143,400-^ 222 = 045 feet 

 of piping required. Even this in severe weather is an excess of 

 piping, so that by adopting Hood's rule for determining the 

 feet of piping required we need not heat the pipes so highly 

 as were the rule of Tredgold adopted. 



Although it is desirable to have a large rather than a small 

 amount of heated surface, the cost of the one is very much 

 greater than that of the other. Some, though aware that a 

 small extent of piping radiating heat at a high temperature is 

 not so good for healthy vegetable growth as a larger surface at 

 a lower temperature, are, nevertheless, from pecuniary con- 

 siderations, desirous of employing no more piping than is 

 absolutely necessary, the pipes being heated to the maximum 

 of 200°. The minimum amount ol piping would seem to be 

 secured when we take as the temperature of the external air 

 that of the mean temperature of the coldest half of the year 

 or winter months, which in this country is 40". 



I have a greenhouse which is 26 feet square, and by Hood's 

 rule, the external temperature being considered 40°, and the 

 house to be kept at a maximum of 50' from fire heat, we have 

 125 X 10 = 1250 -^ 150 = 8 X. 5408 = 43204 4- 222 = 190 feet of sur- 

 face at a temperature of 200°, the actual piping employed 

 being 182 feet of l-inch, or two pipes, a flow and return on a 

 level all round, except doorways. This amount of piping, 

 though sufficient to keep out frost, is not to be advised, as the 

 heat is given out at so high a temperature as to dry the atmo- 

 sphere too much in the immediate vicinity of the pipes. The 

 temperature of the external air may, for this country, be cal- 



