ii»j 4, 1876. ] 



JOURNAL OF riORTICDLTURB AND COTTAGE GARDENER. 



3i9 



being smootb and bright greeu with the veins marked out 

 witli golden yellow. The elegant slender stems, which are 

 when developed of a deep red colour, are slightly pubescent 

 on their under surfaces, which gives to the plant an elegant 

 appearance. This climbing plant when used as a carpet soon 

 covers the ground, and it is singularly handsome. Propagate 

 in spring for the bedding season. 



1. Stachys lanata. — This ia a large woolly-leaved plant, 

 hardy and easily propagated by seed or division, but seedlings 

 are the best, for the leaves grow much longer, and the plants 

 are not apt to run to seed as cuttings or divibions. — N. Cole. 



A BATCH OF SPRING BEAUTIES. 



Floweps are springing up everywhere, telling us of brighter 

 and happier days amid the fierce blasts that we have recently 

 experienced. On April 14th the thermometer indicated 8° of frost 

 at six o'clock in the morning, yet many flowers have survived 

 even such treatment; among which I notice Adonis vernalis, 

 Erythronium Dens-canisand E. Dens-canis alba, real gems ; Fi- 

 caria Ranunculus flore-plena, Iberis sempervirens, Ooipbalodes 

 verna, Sisyrinchiam grandiflorum (needs protection in a season 

 like the present), Draba gigas, Aubrietia Campbelli, Dondia 

 Epipactis, Orobus vernus, Myosotis dissitiflora, Dielytra exi- 

 mia, Cheiranthua alpiuus. Iris pumila; double white, sulphur, 

 lilac, and crimson Primroses ; Polyanthuses in almost endless 

 variety, Helleborus atro-rubens, double and single Hepaticas 

 of various colours. Narcissus Ajax, Paobysandra procumbens, 

 Viola odorata, Palmouaria siberica, Scilla bifolia, S. eiberica, 

 Lamium maculatum, Alyssum compactum, Bulboeodium ver- 

 num, Caltha palustris, C. palustris plena, Arabis purpurea, Gagea 

 lutea, Eriuns alpinns, Corydalis bulbosua, Bellis perennis plena, 

 Veronica siberica, V. speciosa, Arabis luoida variegata, Asarum 

 europseum. Narcissus bulboeodium (N. bulboeodium alba should 

 be in all gardens), sanguineum grandifiora, and a host of 

 othera too numerous to mention. — M. H., Campliill, Bedalc. 



DISTRIBUTION OF HEATING SURFACES.— No. 2. 



In early forcing, and houses required to be kept at a high 

 temperature at the coldest and dullest period of the year, the 

 importance of the distribution of the heating surfaces and the 

 means of ventilation does not appear to have had the attention 

 it deserves. The beating surfaces are in most instances placed 

 along the sides of spans and at the front of lean-to's. This 

 arrangement of the heating surfaces — their concentration at 

 the sides or fronts, the pipes alongside and over each other 

 — has no parallel approximative with natural beat ; but I must 

 urge that in the case of the antiquated mode of heating by 

 hotbeds of fermenting materials and by bottom beat bad from 

 chambered beds heated by hot water we approximate very 

 nearly to natural heat, and the nearer we approach thereto the 

 more certain are we of satisfactory results. 



By the hotbed system (it is still a system) we have the beat 

 given out by the surface of the bed equally throughout. This 

 equality of warmth is recognised as the very best means of 

 aecuring a free and equal breaking of the earliest-forced Vines. 

 It ia a ready means of affording warmth and moisture with 

 greater regularity than warmth irom hot-water pipes and 

 moisture by sprinklings of water from a syringe. There 

 is, therefore, great similarity between hotbed and natural 

 heat. Solar beat passes through glass, and is also trans- 

 mitted through air without heating it ; hence the highest 

 extreme of temperature is found at the earth's surface, the 

 heat transmitted being in part refracted and in part absorbed, 

 radiation only taking place when the atmosphere is colder 

 than the earth. In a glass structure solar heat is trapped. 



Now, the glass by which solar heat is admitted appears to 

 intercept heat in proportion to its thickness, for uncolonred 

 glass, which intercepts little if any light, will stop two-thirds of 

 the heat, thick glass intercepting more heat than thin. A 

 large house will have a considerably lessened extent of cooling 

 surface as compared with one of considerably less size, hence 

 the temperature of the large house will take longer in cooling, 

 and will be maintained at a more equable temperature. The 

 thicker the glass the longer will solar or artificial heat be in 

 cooling. 



The advantage of thick glass over thin for all horticultural 

 purposes will be apparent, inasmuch as it enables ns to retain 

 accumulated solar and artificial beat without so speedy a 

 diminution of temperature as when the glass is employed. 

 15oz. glass has given way to 21-oz., and I have found 32-oz. 



sheet glass better in every respect than '21-oz. I have also 

 42-oz. sheet, quarter-inch plate and half-inch, and five-eighth 

 rough plate, which is decidedly superior in the houses glazed 

 therewith for beat-retention to bouses glazed with thin glass — 

 15-oz. to the foot and less. I may just say that clear glass, 

 no matter what its thickness, obstructs no light, and is not 

 heated by the transmission of solar light ; but I am bound to 

 say that rough plate glass does become heated, a clear proof 

 that it does stop solar heat — absorbs it, benefiting more the 

 atmosphere outside than that of the structure. 



But what has glass to do with the distribution of the heat- 

 ing surfaces? Much. By it we admit auxiliary beat, and by 

 the same we suffer diminution of the beat produced and sought 

 to be retained. The glass is the point where the struggle for 

 mastery is fought between the artificial heat and natural cold. 

 If the glass be such as to allow of the heated atmosphere 

 rapidly cooling the effect will be that the heated surfaces must 

 be kept at a higher temperature, meaning a more highly heated 

 furnace, an increased consumption of fuel ; whilst if the glass 

 prevent rapid cooling of the heated enclosed air, the beating 

 surfaces will, to maintain the same or a similar temperature, 

 require to be less highly heated, a saving of fuel being fl'fected. 

 I also find that the glass between thick and thin makes the 

 difference of a 4-inch hot-water pipe in 12 feet of width of an 

 ordinary structure in favour of the former, and a considerable 

 difference in the penetration of the heat radiated. With thick 

 glass its penetration ia a fourth more than with thin. Four 

 pipes will not be more availing with thin glass than three pipes 

 with thick glass. 



Were it practicable the highest perfection in the distribution 

 of the beat-radiating, heat-affording surface, would appear to 

 be found in its greatest extent of surface — i.e., soil or floor 

 surface, for the greater the extent of heating surface the 

 temperature thereof will be lessened proportionate to its in- 

 crease, as it must be increased in temperature in proportion to 

 the lessened extent of heated surface. Those having beds in 

 bouses heated by hot-water pipes for affording bottom heat to 

 Pines, Cucumbers, &«., know well enough that the piping for 

 top heat ia not required to be kept at so high a beat aa in 

 structures which have not hot-water-heated hotbeds, and the 

 value is recognised of a bed of fermenting materials for start- 

 ing Vines. If an extended heating surface, giving off heat at 

 a comparatively low temperature, be a good thing at the start- 

 ing of Vines, it certainly could not be a bad thing were it 

 continued throughout. A hotbed giving off beat at lesa than 

 100° must be better than heat given off by hot-water pipes 

 at 200° ; the surface of the former is considerably greater. 

 The heat with the moisture is more equable by the hotbed than 

 the hot-water pipes, and is more conducive of free and regular 

 growth, because more closely approximating nature. I do not 

 pretend to contend for the practicability of such a system. I 

 I know that in the case of fruit borders they would, by an ex- 

 j tension of the heating surface to the whole or a much greater 

 part than at present, be practically nullified for watering and 

 the action of air, but for plant structures there could be no 

 reasonable objection to heating with tanks, over which could be 

 the staging, or in fact the pots might, as we should not need to 

 have the surface heated to an injurious temperature, be placed 

 upon the tanks. Tanks, though we are prepared to admit 

 them the best of all modes of affording artificial warmth, are 

 costly, and not generally applicable ; we are therefore for the 

 present confined to boating with circular hot-water pipes, but 

 the day may not be distant when we shall have rectangular 

 pipes — extended radiating surface without increasing the water 

 space. 



Taking things as they are, I consider that the placing of hot- 

 water pipes at the sides or front of houses ia — when forcing is 

 going on at midwinter, or in fact at any time when the tempe- 

 rature is mainly dependant upon artificial means — one of the 

 greatest mistakes in horticultural engineering. What matter 

 where the pipes are placed, only we secure the desired tempera- 

 ture? That it does form subject for consideration may be in- 

 ferred from the advocacy of roof-heating by having small-bore 

 pipes beneath the rafters to prevent the accumulated heat 

 being cooled by cold at its entrance. There may be some good 

 in this idea. It will prevent drip by keeping the glass at a 

 more equable temperature with the atmosphere. The moisture 

 resulting from evaporation will not be subject to condensation, 

 and it will also be advantageous in lessening the necessity for 

 so much heat being radiated by hot-water pipes in front or at 

 the sides of the structure, at which point it must be said we 

 have in nature the centre of cold, we artificially make it the 



