88 



GARDEN WALLS. 



reducing the open space a in the flued 

 wall to about 30 inches, the damper 

 may be dispensed with ; but by retaining 

 it, the heat can be regulated according to 

 circumstances." 



We have made this long extract, be- 

 cause we are convinced that this is the 

 most complete system of heating by 

 smoke flues hitherto accomplished. We 

 do not, however, think it by any means 

 so good as heating by hot water, whether 

 in pipes or gutters. 



Ewing's patent glass walls. — The applica- 

 tion of glass in the construction of gar- 

 den walls is only one of the many uses to 

 which this most imperishable of all mate- 

 rials may be applied. We had thought 

 of the probability of such an application 

 at a very early time in the preparation 

 of this work, not dreaming, however, 

 that such an application was soon to 

 be realised. We confess that our ideas 

 went no further than securing durability 

 and elegance at a cost much less than that 

 of the unsightly brick and still more un- 

 sightly stone walls hitherto in use, by 

 employing glass in the way we have 

 described pavement and slate walls to 

 be constructed. It was therefore with 

 much pleasure that we were private- 

 ly informed, some months ago, of Mr 

 Ewing's invention ; and this pleasure was 

 increased when we were favoured by him 

 lately with drawings of it. The accom- 

 panying plate and description will clearly 

 show their construction. But, first, we 

 should state something of the advantages 

 expected to be realised from their use, as 

 well as the disadvantages, if any, that 

 may exist. 



We believe Mr Ewing's walls will 

 insure complete protection to the blos- 

 soms in spring, which open walls do not 

 afford; that they will ripen many fruits, 

 and consequently the young wood of 

 various kinds of fruit trees too delicate to 

 withstand with impunity our variable 

 climate — which walls, as at present con- 

 structed, do not in all situations and sea- 

 sons sufficiently accomplish; that they 

 will improve the flavour of the fruit by 

 keeping it dry, and consequently increas- 

 ing the temperature around it ; that they 



will present to us the means of ripening 

 the peach and the grape at much less ex- 

 pense than in the cumbersome and ex- 

 pensive peach-houses and vineries, as too 

 often at present constructed, and of eco- 

 nomising fuel — as the space to be heated, 

 when artificial heat is required, is small 

 when compared with that of ordinary hot- 

 houses. Another important advantage is 

 their excluding rain, while they admit 

 nearly as much light to the trees as if 

 they were in the open air, and at the same 

 time permit the fullest amount of venti- 

 lation to be given in all weathers. They 

 will secure the preservation of the young 

 wood and foliage during the evaporating 

 and blighting winds of spring, and sudden 

 changes through the summer, by which 

 alone the health, and consequently the 

 age, of the trees will be preserved and 

 prolonged. And last, although not least, 

 they will permit the abandonment of 

 brick and stone walls, which are both in- 

 elegant and expensive structures. 



These are the general advantages, so 

 far as they can be stated at present, in 

 the absence of practical experience. 



That objections will be started to this 

 innovation upon long-cherished usage is 

 certain. Let us now inquire as to the 

 grounds of these. The angle of elevation, 

 upon which so much stress has been laid 

 by some, is here comparatively disregard- 

 ed, as these glass walls stand perpendicular 

 to the earth's surface, or nearly so. Would 

 not, therefore, a departure from the per- 

 pendicular be better adapted for the 

 transmission of the rays of solar heat and 

 light to the trees within?* The amount 

 of heat gained by hollow glass walls, when 

 solar rays only are depended on, may 

 amount during the day, when the requi- 

 site ventilation is in full operation, to 

 about 6° or 8° above that of the external 

 air. This, no doubt , is a considerable addi- 

 tional degree of temperature, but it 

 would be much greater if there were a 

 heat-absorbing and heat-reflecting me- 

 dium placed within the walls ; for neither 

 the foliage nor branches would absorb or 

 reflect that element. Any opaque body 

 introduced would greatly diminish their 

 transparency, which, barringthis objection, 



* Since our plate was engraved and issued, we have heard from Mr Ewing that this suggestion 

 has to some extent been anticipated : his glass walls being now constructed 4 feet wide at bottom, 

 and 18 inches at top, and thus receiving some degree of inclination. 



