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and three feet endways. On each acre there were J23O beds, and 61,5O sets, or five to each bed, viz. one at each corner, and one in the middle- The sets of potatoes, when planted according to the usual most approved practice, in three feet stitches, and nine inches apart, amount to about twenty thousand. In the present, and indeed in all seasons when potatoes are scarce, the saving in planting is a considerable object. A great advantage also arises in being able to keep the potatoes and manure from wet. In the late uncommonly wet season I sustained little or no loss in my mode, which was not the case in many of the driest grounds. This plan unites hand hoeing with Jiorse culture, and will be found serviceable in wet soils.
The lateness of planting, together with the premature frosts, prevented my forming a fair judgment as to the quantity per acre which might ibe obtained by this method. My view in fixing upon this plan was, to enable me to judge of the effects of evaporation, by being able to continue my operations for a longer period. I have no doubt but that in common seasons, notwithstanding the increased distance, the whole ground would be covered.
My experiments on cabbages this season commenced by planting them early in April. From the rain
[rich fell subsequently, and continued till the begin, ning of May, succeeded by severe east winds, the earth became so hard and baked, that the plants had made very little progress.
In the first week in June the ploughs were set to work: as they started, Mr. Ponsonby,_of Hail Hall,
xvas present, and saw the "crop; it was with difficulty that the ground was first broken, but by the end of the week it was brought into fine tilth. Notwithstanding the whole week had been dry, with a strong sun and severe east wind, yet such was the progress in growth of the cabbage, that when seen again by that gentleman on the Saturday, he could scarce be persuaded they were the same plants.
During these operations I had been making constant experiments with glasses, contrived for the purpose, to ascertain the quantity of evaporation from the land, which I found to amount, on the fresh ploughed ground, to nine hundred and fifty pounds per hour on the surface of a statute acre, whilst on the ground unbroken, though the glass stood repeatedly for two hours at a time/ there was not the least cloud upon it, which proved that no moisture then arose from the earth.
The evaporation from the ploughed land was found to decrease rapidly after the first and second day, and ceased after five or six days., depending on the wind and sun. These experiments were carried on for many months. After July the evaporation decreased, which proves that though the heat of the atmosphere be equal, the air is not so dense. The evaporation, after the most abundant rains., was not advanced beyond what the earth afforded on being fresh turned up. The rapid growth of my potatoes corresponded perfectly with the previous experiments; and their growth in dry weather visibly exceeded that of other
T crops (Crops where the earth was not stirred. The component parts of the matter evaporated remain yet to be ascertained; the beneficial effects arising from it to vegetation cannot b.' doubted or denied, but whether they proceed from one or more causes, is a question pf much curiosity and importance.
May not a similar process here take place, as when water is exposed to the action of the air in irrigation? Is it too much to suppose some natural operation to. take place in the earth, which may decompose the oxygen contained in air from the hydrogen, during the absence of the sun, which on the sun's re-appearance may be again given out in a state highly propitious to vegetation? Oxygen is found to contain carbon; and may not the growing plants imbibe it from the air, and may we not thereby account for its forming a constituent part of all vegetables?
The investigation of these objects presents a wide field for inquiry, and may lead to very important discoveries. From more or less oxygen contained in the earth, may not its proportions account for the fertility of one soil above another? May not the advantages supposed to be derived from loosening the soil, proceed from its being thus rendered in a fit state tq imbibe the air? Fallows soon become so hard upon the surface, as neither to be capable of absorption or evaporation. One very important result is placed before the eyes, and within the reach of every practical agriculturist to ascertain, namely, that the evaporation from dung is five times as much as from
earth, and is equal on the surface of an acre to 50OO pounds per hour. By making use of dung in its freshest state, the farmer may extend his cropping to one-third more land with the same quantity of manure. It is with regret that I have viewed in many parts of the kingdom the quantity of manure which is exposed on the surface, and tends to no good. I am strongly of opinion,, that in all light soils, if the manure was buried in trenches as I propose, and the turnips sowed above it, that more abundant crops would be procured. By cleaning with the plough, great advantage would be derived to the crop, from the evaporation yielded by the earth. Hot manure might also be used. By fermentation dung is reduced to one half its bulk, and its quality reduced in a much greater proportion. The manure now commonly taken for one acre of broad cast, would, if deposited whilst hot in drills, answer for four acres, and the crop produced be much more.
If the Society of Arts extend their sanction and patronage to my exertions, I shall feel bound to proceed, and to endeavour to bring the experiments to a regular system. The glasses I used for determining the quantity of evaporation were of a bell form, and placed with the open part upon the earth; a quantity of tow was first weighed, ready to wipe off the moisture collected from evaporation within the glass, which tow was then again weighed as exactly as I could after the glass had stood for a given time, and been wiped dry with the tow; and from knowing the contents of the glass I made my calculations. Mr, Robert Wood,
T 2 watch
watch-maker, of Workington, attended to the experiments made with the glasses.
I have the honour to be, with great respect,
Your obedient humble Servant,
J. C. Curwen,
Workington-Hall, Jan. 9, 1608. To C. Taylor, M.D. Sec.
It is with great pleasure and satisfaction that I learnt yesterday from Mr. Arthur Young, the Secretary of the Board of Agriculture, that he has adopted my ideas of the great importance of evaporation, and that he has actually ordered Mr. Blunt, optician, of Cornhill, to construct him an instrument for ascertaining the evaporation, which instrument I shall request Mr. Blunt to show to the Society. Mr. Young intends in the course of the summer to make a variety of experiments on the quantity of evaporation produced from different soils, agreeing with me, that the greater or less degree of if, influences most materially the luxu* ranee or growth of the crop.
In all the valuable tracts which Mr. Young has given to the world., he has never adverted to this, and the first knowledge of it as a principle for promoting the growth of crops was obtained from tny account of the Schoose Farm, in the report of the Working* ton Agricultural Society, of which he is a member.