170 THE FLOEAL WORLD AND GAUDEN GUIDE. 



Now you may ask why this particular form of house in preference to 

 any other. Let me therefore remark, that to grow roses under glass you 

 need protection from frost and excessive wet in winter, this a glass house 

 of any kind will . supply. But you need all the help possible from sun- 

 heat in spring, for sun-heat to roses is as much superior to fire-heat as 

 fire-heat is superior to no heat at all Avhen frost rages for weeks together. 

 With such a steep pitch there is an immense gain of sun-heat in spi'ing, 

 and this house is generally four degrees warmer than one of lower pitch 

 ■would he from an early hour in the morning, from the beginning of 

 March to the middle of May. Therefore the roses are greatly assisted to 

 bloom early and strong. Eut during the summer there is need rather of 

 coolness than heat ; certainly we do not want roses to be kppt in an oven 

 from June to August, and it happens that when the sun gets high in the 

 heavens a steep pitch catches less of his rays, and a low roof is preferable 

 to collect sun-heat. So by the use of this form of house we get aid from 

 the sun when we most need it, and when an increase of the natural tem- 

 perature is no longer desirable, there is the least possible difterence 

 between the temperature in the house and out of doors. 



But the value of this style of building is not merely in the angle of 

 the lights, for a house of any other kind could be built to the same angle, 

 and these Paxtonian houses can be made as flat as any others, and are 

 . often so made for growing pines and other such things. 33ut there are 

 two special advantages, and the first of these is the perfect system of ven- 

 tilation. The ventilating shutters are in two divisions, the whole length 

 of the lights, and admit air either from the ground to the roof, or from 

 the ground half way up, or from the ridge half way down, at the will of 

 the cultivator. Thus there can be kept up a continual circulation of 

 top air, which is desirable on sunny days in spring, or of air the whole 

 length, which is desirable day and night all the summer in the case of 

 roses, and the ventilators of this h ouse have all been open day and night 

 since the first week in June. I firmly believe that there is no system 

 known equal to this for maintaining throughout the house a constantly 

 moving atmosphere, the breeze plajing through the leaves without vio- 

 lence, even when a gale is blowing, and still moving even when the air 

 outside is at a dead calm. The heat of the sun striking on the glass and 

 wood, causes all the air in the house to rise and escape at the edge of the 

 ridge-board, this is the origin of the circulation when the air outside is 

 still. The upward motion causes an inward flow of air at the bottom, 

 and thus stagnation is impossible, and Phoebus himself works the wind- 

 mill exactly at the rate needful, for the fiercer his heat the more rapid 

 the escape of air at top and influx at bottom. 



Our rose-growing readers Avill fully appreciate the importance of all 

 this. A stifling atmosphere is death to roses, no matter if teas or what 

 else. But they want no artificial heat to produce a good bloom, if the 

 cultivator ia content to wait till the sun brings them out naturally. 

 Therefore this house is not heated in any way, and as an indication of 

 what may be done without fire-heat, it will sufiice to say that many of 

 the roses in the house were in full bloom in the first week of April 

 this year, and by the second week in May they were all out or covered 

 with expanding buds, and so they continued till the end of June, when 

 they were resting from their exertions, and preparing for a fine bloom all 

 the late summer and autumn. 



