May 23, 1867. ] 



JOUBNAL OP HOETICUIiTUEE AND COTTAGE GAKDENEB. 



355 



by its destroying weeds. Moisture abounds in the atmosphere 

 during the hottest months, and it is absorbed and retained 

 most abundantly by a soil which is in the most friable state. 

 Professor Schuliler found that one thousand grains of stiff 

 clay absorbed in twenty-four hours only thirty-six grains of 

 moisture from the air; whilst garden mould absorbed in the 

 same time forty-five grains ; and fine magnesia seventy-six 

 grains. Then, again, pulverising the soil enables it better to 

 retain moisture absorbed. This we demonstrated some years 

 since ; and the reason is, obviously, because a hard soil be- 

 comes heated by the sun's rays much more rapidly than one with 

 a loosened texture. The latter is better permeated by the air, 

 which is one of the worst conductors of heat. We are glad to 

 find our opinions confirmed by so practical and so intelligent a 

 man as Mr. Barnes, gardener to Lady RoUe, at Bictou Gar- 

 dens, Devonshire. He says, ' I do not agree with those who 

 tell us one good weeding is worth two hoeings ; I say. Never weed 

 any crop in which a hoe can be got between the plants ; not so 

 much for the sake of destroying weeds and vermin, which must 

 necessarily be the case if hoeing be done well, as for increasing 

 the porosity of the soil, to allow the water and air to penetrate 

 freely through it. I am well convinced, by long and close 

 practice, that oftentimes there is more benefit derived by crops 

 from keeping them well hoed, thpn there is from the manure 

 applied. Weeds, or no weeds, still I keep stirring the soil ; 

 well knowing, from practice, the very beneficial effect which 

 it has.' "J 



VINES AND VINE BORDERS— NATURAL 

 TEMPERATURES. 



In my last I endeavoured to show Mr. Wills that off-hand 

 remarks are not argument, and that they do not help to throw 

 much light upon a subject under discussion, though they may 

 sometimes be taken up and turned round in a manner the 

 writer never contemplated. In this paper I shall try and answer 

 "H. S." 



Ever since I read that the orchard-houses at Sawbridgeworth 

 conferred upon their occupants all the advantages of the climate 

 of Toulouse, I have been trying to find out what that climate is, 

 and to this day without success. When, therefore, I read in 

 " H. S.'s " letter (page 274), this remark, " that in saying the 

 45th degree of north latitude enjoyed a mean temperature of 

 from 70° to 73° during the summer months, he was only giving 

 a fact that every gardener ought to be acquainted with," I was 

 led, I was going to say for the hundredth time, to wish that 

 information upon these subjects was more easily obtained, and 

 that editors of horticultural works would give the matter their 

 attention to the advantage of the public. " H. S." may know 

 where to find the information ; if so, he has been more fortu- 

 nate than I, in which case, when I point out to him the im- 

 portant omission he has made, I hope he will supply my want. 

 As I have said that I have failed to find such information in 

 horticultural works, your readers will, I hope, excuse my going 

 to meteorological publications, and, notwithstanding the un- 

 inviting name, let me here say that they will find the " Journal 

 of the Scottish Meteorological Society," under the editorship of 

 Mr. Alexander Buchan, as interesting a work on horticulture as 

 they will meet with. Let me take the liberty of giving an 

 extract from his paper " On the Weather Conditions which 

 Produce Large Crops of Cereals," and they shall judge of the 

 value of one at least. 



" The weather of this period was drier in 1863, and the sun- 

 shine greater than in 1861 ; and the temperature of the day 

 was about equal, but of the night about 3° lower in 1863 : 

 hence, though the temperature of the air was no warmer in 

 1863, but during the nights rather colder, yet the weather of 

 that year must be regarded as more conducive to the ripening 

 of the crops, owing to its greater dryness and to the greater 

 sunshine, which brought the crops, as it were, into more im- 

 mediate contact with the sun, so that they ripened under a 

 higher temperature than was indicated by the thermometers 

 placed in the shade." Again, he says, — "Thus at Sandwich, 

 on the 26th of July, 1861, when the protected thermometers 

 stood no higher than 55.1°, the ears of corn were ripening in a 

 temperature of 80.2°." 



Thus, I have found that no less an authority than the Secre- 

 tary of a Meteorological Society is of my opinion, that for farm- 

 ing and horticultural purposes, mean temperatures which are 

 founded on temperatures in the shade are only calculat5d to 

 mislead in making comparisons between one year and another, 



and, therefore, we must follow the same rule in making a com- 

 parison between the French climate at the 4.5th degree of north 

 latitude, and the temperature we should maintain in our Vine- 

 houses during the day. But we have lately read in another 

 journal some papers on the power which moisture in the at- 

 mosphere has, even though invisible to us, to prevent the loss 

 of heat through radiation, and also the interesting discussions 

 these papers provoked. This is simply a branch of the same 

 subject ; and though some have told me it was too highly scien- 

 tific for them to understand, or to think of much practical use 

 to gardeners, let us turn to the .Tournal of this Meteorological 

 Society to find some experiment that will simplify it till it 

 comes within the range of our comprehension. 



Two months since there was a sale of new Orchids advertissd, 

 part of which, it was said, were found growing at an elevation of 

 from 12,000 to 16.000 feet on the Cordilleras of Ecuador. What 

 this climate is I do not knosv, but by the theory " H. S." has 

 given us, if it were anywhere in Europe it would be within the 

 limits of perpetual snow, and, therefore, would have a "mean 

 temperature" low enough to warrant any cool treatment; but 

 in practice it will be found entirely to depend on the dryness 

 or humidity of the atmosphere, as altitude considered apart 

 from latitude makes no difference in the power of the sun's 

 rays, as those who have toiled up a Swiss mountain imder a 

 burning sun can have no difficulty in testifying. About 

 10,000 feet has been the most lengthened of my experiences, 

 and on that day I was made aware that what Mr. Alexander 

 Buchan speaks of as the extra power of the sim in dry and 

 sunny weather was not theory ; but I will give the figures that 

 it may be seen wh.at sort of a climate such an Orchid would 

 require had it been found upon the Pic-du-Mili, which is a 

 mountain just upon the 43rd degree of north latitude, and. 

 having an elevation of 9439 feet. The comparison is made with 

 Bagneres, a town situated at its foot, the elevation of which is 

 1808 feet. The first result given is an average of twenty-two 

 observations taken simultaneously at the two places between 

 7 A.M. and 2 p.m., " in a clear .oky, full sun, and calm air." At 

 Bagneres, air in the shade, 72.1° ; soil on the surface in the full 

 sun, 97°. On the Pic-du-Midi, air in the shade, 50.2°; soil oa 

 the surface in full sun, 92.8°. The second result is the absolute 

 maximum in the sun and the corresponding in the shade. At 

 Bagnfires, in the shade, 80.8° ; in sun. 122.5°, on the 9th of 

 September, at 2 p.m. On the Pic-du-Midi, in shade, 55.8° ; in 

 sun, 126.1°, at 11.30 on September the 10th. To show the rapid 

 manner in which the soil is heated, at 7 a.m. it was only 48.7°, 

 and at 11.30, 118°, on cue occasion upon the Pic-du-Midi. The 

 lowest minimum was, at Bagneres, air 58.8°, soil 57° ; on the 

 Pic-du-Midi, 34.3°, soil 32.2° — both taken upon the night of 

 September 9th. Such are the vicissitudes of the temperatures 

 of the air and soil during twenty-four hours upon a mountain 

 in the 43rd degree of north latitude, 9439 feet high. What they 

 are at an elevation of from 12,000 to 16,000 feet under the line- 

 of the equator I do not know. My intention is not to injure the 

 sale of these Orchid-, or to discourage their cultivation, but to 

 point out, as these experiments undoubtedly do, that the power 

 of the sun's rays cannot be judged by " mean temperatui'es in 

 the shade," any more than the mean night temperature wiU 

 show how much heat the soil has lost by radiation, as they 

 both depend on the moisture the atmosphere holds in sus- 

 pension. There are few counties in England that cannot 

 show within the distance of twenty miles two distinct climates 

 caused by one being '■ much drier and, therefore, sunnier than 

 the o'her.' ' 



" H. S.," from what he says, has lived longer in France than 

 I have, my vifits having been limited by the time I could 

 spare from business ; but as these visits have been at most 

 periods of the year, I have been able to observe that the spring 

 season in France is not as much earlier in proportion as the 

 summer, and that therefore the reason of the period of ma- 

 turity of their harvests having gained npou ours at a much 

 greater rate than the difference of the mean temperatures 

 would indicate, is that it is " drier and sunnier," but of the 

 value in figures of this advantage I am ignora'jt, as I have not 

 found any French meteorological table containing, as those of 

 our two societies do, a column for heat in the sun, and I am 

 this important point s'aort-before I can know all the advantages 

 of the climate of Toulouse. M. Cb. Martina's paper supplies 

 me with one item — that on the 9th of September, ly the way 

 not the hottest month either, at Bagneres 80 8° in the shade 

 gave 122.5° in the sun, and that town is only six-tenths of a 

 degree south of Toulouse. In June, in Londoo, I have before 

 shown 80* in the shade can give 130° in the stm. If " H. S." 



