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by the second and third methods mentioned, and his statements as to the yield of plants electrically treated and plants untreated, placed under exactly similar conditions in every other respect, favour the idea that an increase of crop follows the use of electricity.

It is, however, in its use as a motive power that the electric current is destined to prove of the greatest assistance to the agriculturalist. The work which has already been done in this direction is only an earnest of what may be expected. The utilisation of waste power is one of the most important economic questions of the day. How to conserve and employ in the best manner the vast stores of energy continually being given out by the sun, and stored up in one way or another upon the earth, is one great aim of the modern engineer. It has been thought by some that waterfalls were made more for ornament than for use; probably, it has never occurred to them to think out the similarity between a coal field and a mountain lake. What is coal, viewed from the engineer's standpoint, but an accumulator? Work was done upon it by the sun, ages and ages ago, and placed under proper conditions, it is able to give out again that energy in almost any desired form.

A mountain lake, in like manner, is an accumulator of energy. Work was done upon the water, of which it is composed, by the sun, in raising it from the sea level to the clouds, in the form of vapour; part of that energy was given out again when the rain fell, but a portion equivalent in amount to that required to raise it to that height, is retained in the water, and by employing suitable means, we may, as in the case of coal, use it in the way which may appear most suitable to us.

this

It is now possible, by the use of electricity, to utilize power in other and more economical ways than by

simply using the old-fashioned overshot waterwheel to drive a mill placed close to the waterfall. Engineers have been at work at perfecting waterwheels and turbines, amongst the best known being the Pelton and Girard types, which are now largely used for electrical purposes. These motors are constructed to work at varying speeds, and are usually coupled direct to dynamos or electric current generators, machines which are able in many cases to transform into electrical energy ninety-four and ninety-five per cent. of the power used to drive them.

A dynamo is a reversible machine, that is to say, when caused by mechanical power to revolve, it produces an electrical current, whilst if the reverse takes place, and the electric current is passed through the dynamo from an outside source, it will revolve and when connected with other machinery, put that machinery in motion and convert in some cases about eighty or ninety per cent. of the electrical energy into mechanical power, as electricity may be transmitted along copper cables for long distances with very little loss. We are able in this way to transmit power from where it is not wanted to a distant spot where it may be economically utilised. Not only this, but by observing simple electrical rules in the selection of the electrical pressure at which the power is transmitted, and the kind of electrical motor used, we are able to obtain a complete control over the speed at which the motor works, either having the speed vary with the work, running fast when it is light and slowing down as it increases, or running at a steady speed, no matter how the work done varies: this control of the motor speed being essential for many kinds of work, and constituting a feature of great utility in the electrical transmission of power.

Water power is used in many places as the motive power for driving at a distance all kinds of agricultural machinery. Threshing, chaff-cutting, and similar machines may, of course, be operated at practically any distance from the source of energy. It is the belief of the writer that in the future many agricultural operations now carried on by horse-power will be conducted by means of a machine carrying an electro-motor and flexible cables conveying the current. Ploughs have in many cases been worked by electricity, trucks containing electromotors being placed at each end of the furrow with a chain attached to the plough, like the ordinary steam plough arrangement. One of the best known instances is the estate of the Marquis of Salisbury at Hatfield. There, the water power on a distant part of the estate is utilized at various points for different purposes, such as lighting the house, pile driving, chaff cutting, threshing, and a variety of other purposes. At Millas, in the Western Pyrenees, on property belonging to Mr. Comille Gonzy, the power generating from a neighbouring stream is converted into electricity, and this current operates the motor for driving grape crushing machines, works the pump for the vineyards, and supplies sufficient current to light one hundred and eighty incandescent lamps used to illuminate the farmhouse and outbuildings; doing all this at a very small cost indeed. These instances, if we had space, might be multiplied.

A windmill for years has been used as a very cheap source of power both for pumping and for grinding of corn. Mr. C. F. Brush has arranged in his garden at Cleveland, Ohio, a windmill, which is used to drive a dynamo, and produce electrical energy, which, stored in accumulators until wanted, is sufficient to light one hundred lamps in the house. While on this subject we

might mention that wind power is used at Cape de la Hague, in France, to supply accumulators with electrical energy for lighting the arc lamps used in the lighthouse.

Reverting again to more strictly agricultural topics, we find that efforts have been made to usefully employ electricity in the dairy, it having been ascertained that a weak current may be used to expedite the separation of the cream from the milk. It has been stated that it is the formation of oxygen during thunder-storms by the passage of the electric current which causes butter and other liquids to turn sour, and also that the same effect may be artificially produced by electric currents of high tension. Imperfectly exhausted glowing incandescent lamps have been immersed in barrels containing new wine to keep the temperature at a point favourable for rapid fermentation, and numerous experiments, more or less successful, have been made towards the improving in quality wines and spirits by the passage of an electric current.

Some experimenters have tried to utilise the passage of a low voltage alternating current as a means of killing the spores which cause fermentation, and so furnishing a means of fixing the age of any wine. There is risk, however, in a case such as this, that the process of oxidation which goes on would be carried too far, and finally result in the alcohol itself being turned into acetic acid.

The above is a brief résumé of a part of what has been done up to the present in applying the electric current to agricultural purposes.

FREDERICK L. RAWSON.

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CHAPTER LXXXI.

AGRICULTURAL GEOLOGY.

BY PROFESSOR PRIMROSE MCCONNELL, B.Sc.

Author of The Agricultural Notebook,” and numerous other agricultural works; High. Soc. First Prizeman in Agriculture, Edinburgh University; Fellow of the Highland and Agricultural Society of Scotland; Member of the Royal Agricultural Society of England (by Exam.); Assistant Examiner, Principles of Agriculture," Science and Art Department; Lecturer on Agricultural Science to the Indian Civil Service Students, Oxford University; etc.

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THE value of the study of geology to all those who have to deal with land was much more fully realized by our forefathers than by the present generation. Any one who looks over the volumes of the first series of the Journal of the Royal Agricultural Society of England, will find many articles dealing with the subject scattered through those pages, and showing that at one time there was a considerable amount of interest taken in the matter. The teachings of agricultural chemistry, which gave more certain and immediate results useful to farmers, however, seem to have overshadowed this department of enquiry, so that the amount of information accumulated appears to have been largely lost sight of. I am of opinion, however, that there is no branch of science of more use to those who farm or manage land in any way than this, and purpose giving a short résumé of what is known already on the subject, and in what way future progress should be made.

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