July 5, 1861. ] 



JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 



is pumped up into the leaves and the process of assimila- 

 tion goes on more slowly, and the result is, fruit not ripe and 

 the growth not perfected so early as with trees under a lean- 

 to house roof. " Wteside " may explain this away by con- 

 tending that a span presenting a larger proportion of exposed 

 surface to the air is sufficient to account for the difference 

 of temperature in favour of a lean-to, which owes its heat 

 to the smaller proportion of glass surface presented to the 

 cooling influences of the atmosphere. I admit it ; but how 

 comes the lean-to to be heated much more quickly than the 

 span ? For the same reason ? Decidedly not. Very well, 

 then, we come to the point at once. A span-roofed house 

 affording light to its inmates on every side, they are in- 

 debted to refraction for all the light on the west side of the 

 house when the sun's rays fall on the east ; and are not 

 Pears on a west wall the same ? Cherries on an east wall or 

 aspect are also indebted to the same refraction when the 

 sun's rays are obscured from them by the bricks that in- 

 tervene between them and the west side on which the sun's 

 rays are falling ; but is the light not less intense on the side 

 of the wall opposite that on which the sun shines ? I sup- 

 pose a wall on the sun-side casts no greater shadow than 

 the sun-side of a glass roof, and the trees upon it receive 

 the sun's rays equally from top to bottom. But who can 

 say the same of a glass roof? Why, the trees beneath it are 

 indebted for the light they receive to that which passes 

 through the glass, directly or indirectly, it is all the same ; 

 they cannot receive any or but little of that right which the 

 angle of incidence causes to be reflected back into space. 

 DT it be as light on the north side of a wall, or ia the shadow 

 of anything that obstructs or causes a deviation from the 

 natural course of the rays as in an open space where the sun's 

 rays are not broken by some substance suspended or other- 

 wise causing a deviation from the natural course of the 

 rays, then are trees under glass in the enjoyment of more 

 light than trees on a south wall. There is an equal amount 

 of light on the earth when the sun's rays are obstructed by 

 the clouds, according to " Wteside' s " argument as when 

 there are no clouds to intercept them. 



" Wteside " again, speaking of light, says that an Apricot 

 on a west wall is deprived of the light which is sufficient to 

 ripen Cherries on the east side by the bricks that intervene. 

 Suppose we take away the wall aud the Cherry trees, would 

 the ;Apricot trees have more light ? Not a particle ; for 

 immediately we take away the wall leaves appear on that 

 side and shut out the light from the others on the opposite 

 side, rendering them as dark as they were when the wall 

 prevented their receiving any light from that point ; and, in 

 addition, they are deprived of the heat absorbed by the 

 bricks and the shelter walls afford. 



Then as to trees on walls shooting at an angle from the 

 wall on whatever aspect, does it not arise from the same 

 cause as that which makes orchard-house trees grow upwards 

 towards the glass ? Surely trees shoot from walls for the same 

 reason as that which causes orchard-house trees to grow 

 upwards, the lowest branches to be weak and continually 

 dying off — viz., towards the point from which the light is 

 most intense. AH trees on walls push their branches to- 

 wards that which is necessary to their existence — viz., light. 

 In whatever position or situation a plant is placed it is 

 always found pushing its leaves towards the light. 



"Does Mr. Abbey imagine that right proceeds only in 

 direct rays from the sun?" asks "Wteside." lean only 

 answer that the theory of light rests on three laws : 1st, The 

 rays of light are straight lines, given and reflected in the 

 same. 2nd, The angles of incidence and refraction are in the 

 same plane, and equal. 3rd, The angles of incidence and re- 

 fraction are in the same plane, and their sines bear an in- 

 variable ratio to one another for the same medium. 



As to the Apricot from a wall with a pallid hue on the side 

 next the wall. Is not that pallid hue due to the absence of 

 the same agents that cause those in an orchard-house to be 

 of a " sickly colour" all over— the absence of sun, its light 

 and its heat ? 



But I must not lose sight of " Wteside " striving to make 

 it appear that I consider it colder under glass than in the 

 open air. If he refers to page 213, he will find that I state 

 that I found the atmosphere 5° warmer in a span-roofed 

 orchard-house than in the open air ; but if he expects me to 

 become conrerted to his views — viz., that heat is not inter- 



cepted by glass, or that orchard-houses owe their warmth 

 over that of the open air to any increase of heat caused by 

 the passage of solar heat with its light through glass, I must 

 say he expects me to assert that which I know to be er- 

 roneous. The best glass is that which stops the most heat, 

 as Hartley's rough plate, for all horticultural purposes, 

 when the structures are heated or not heated, such struc- 

 tures being warmer than the interior of houses covered 

 with 16-oz. glass. Let "Wteside" keep a register but for 

 a week of the temperatures of three structures equal in 

 their cubic measurements, and also equal in the area which 

 is to admit the sun's rays, and make the latter surface of — 

 1, 16-oz. glass ; 2, Hartley's rough plate glass ; 3, oiled 

 paper; and he will find more heat or a higher mean tem- 

 perature under 3 than under 2, and higher under 2 and 3 

 than beneath 1. Further than this, let him take a large 

 pane of glass, and place it over a thermometer so that the 

 sun's rays will pass vertically through it, and he will find 

 the sun's rays do not raise the mercury more than were 

 there no glass over it ; but suppose he place the pane of 

 glass so that the angle of incidence be more than 45°, the 

 mercury sinks proportionately lower than when under the 

 pane of glass with the sun vertically over it. 



Again : let him erect a house with an angle of 25°, a 

 second 35°, a third 45°, against a south wall, or with an 

 opaque back wall, and complete his experiment by erecting 

 a span-roofed house with the ends respectively north and 

 south, with the roof at any angle he pleases, and glass down 

 to the ground if he chooses ; in short, have glass where we 

 have some opaque material in the first three. All shall be 

 equally well stocked with Peach trees, and all equally well 

 attended to, and which will furnish ripe Peaches the earliest ? 

 Why, they will come in order as named, the span-roofed 

 house being fully a month behind the first of the others, 

 and this with double the amount of " glass not intercepting 

 the heat," according to " Wteside," for it is so hot in 

 houses with a glass roof securing light for the trees enclosed 

 on all sides, as to render the heat quite unendurable. Mr. 

 Rivers tells us such a climate is quite delightful. I myself 

 had any time rather spend a week in a span-roofed orchard- 

 house pinching-back the young growths, or otherwise at- 

 tending to its inmates, than remain an hour in front of a 

 south wall trimming Peach trees trained to it during very 

 hot weather. The air is really so bracing in the former, and 

 so roasting in the other, as to leave no doubt about which is 

 the most comfortable situation to be in. The heat is another 

 question, for heat as determined by the senses is no crite- 

 rion to go by. In fact, degrees of heat and moisture cannot 

 be determined by the senses with any degree of accuracy. 



In conclusion, I can only say that out of the six northern 

 counties of England, and'the whole of Scotland, we have 

 but two cases of Peaches and Nectarines being grown in cold 

 or unheated orchard-houses in that extensive range of 

 country, much the largest half of Britain, one cited at Seg- 

 gieden, near Perth, by " S. R.," and the other by " Pendle," 

 near the famous peak of that name in Lancashire. Mr. 

 Pearson also states the success of orchard-houses at Prescot, 

 but whether Peaches and Nectaries are successfully grown 

 in houses unheated and detached from a wall is not stated. 

 This is all the evidence we have been favoured with relating 

 to the success of orchard-houses in the north. Surely there 

 have been more successes than those named. I have grown 

 Grapes in unheated lean-to houses within the sound of the 

 striking of big "Peter" of York, and had them ripe by the 

 races held there in the last week of August ; Peaches and 

 Nectarines also in unheated lean-to houses in the latter part 

 of July, and beginning of August ; and gathered Earyl Anne 

 Peaches from a south wall in the second week in August ; 

 and gone night and morning with a peck basket and collected 

 fallen Peaches from a net in the last week in August and 

 on through September, and more than once have had to go 

 twice, the basket being too small to take all at once. At 

 Bradford, however, such things are not seen, though I have 

 seen Peaches ripen on a wall, yet I looked into all the 

 hoorchard-uses round there, from that under 20 feet in length 

 up to those 300 feet long and 20 feet wide, and never yet 

 saw a crop in any of them, nor in those situated in much 

 more favourable localities. 



Mr. Rivers, after giving us a racy account of his liking^ for 

 Cherries, and some excellent information as to their cultiva- 



