the French especially did so, and I have been told that within the last fortnight the Government of this country has done the same. For this there exists a very good precedent, because it will be in the minds of many present, that at the battle of Dettingen, George II. confided to the Duc de Noailles his wounded, and subsequently Lord Stair, in writing to the Duc de Noailles to say that he had liberated the whole of the French prisoners, thanked the Duke for the care that had been taken of the English wounded, saying, "Such generosity softens the rigours of war, and does honour to humanity." This appears to have given rise to a treaty between Lord Stair and the Duc de Noailles. I believe in the Seven Years' War a similar treaty existed. I have taken the liberty of mentioning these instances, because they appear to be of much interest. I only regret that the supplementing by voluntary aid, the sanitary service of armies in the field, will not be introduced at an evening meeting, to afford an opportunity for the discussion of that subject. I will conclude by reverting for a moment to the war of the Austrian Succession. I believe it was upon that occasion that Prince Eugène said that 100,000 men would be a better guarantee than 100,000 treaties. We now have an exception to this rule, for I think one treaty in favour of humanity will be more efficacious than the force of 100,000 men. I have now the pleasing duty to perform, of conveying to Mr. Fisher the thanks of this meeting for a most important and a most interesting lecture.

Mr. FISHER: Allow me to thank you, in the first place, for your friendly feeling in asking me to lecture on the subject. As a stranger, and yet not a stranger, for I trust that we in America feel that we are one with you, I must say that I feel honoured on behalf of the United States' Sanitary Commission by the courtesy which has been extended to me by the invitation to lecture here; and I feel greatly honoured by your kindness in listening so attentively, and deeply gratified by the endorsement that you have put, not on American work, but on humanitarian work. In the name of common humanity, I tender you my thanks.

LECTURE.

Friday, February 24th, 1865.

GENERAL SIR JOHN FOX BURGOYNE, Bart., G.C.B., R.E., Director of Works, in the Chair.

THE EMPLOYMENT OF ELECTRICITY IN MILITARY

OPERATIONS.

By Captain II. SCHAW, R.E., Professor of Fortification and Artillery, Royal Staff College, Sandhurst.

Ir is now nearly two years since I first undertook, at the request of the Council of this Institution, to give a lecture on Electricity as applied to Military purposes. Owing to various causes, the lecture has been deferred, and it is a proof of the rapid progress of the age that the facts which I shall now have to bring before you differ in some material points from those which I should have spoken of two years ago. New instruments have been invented, new discoveries made, and our knowledge of the subject has advanced so far, that electricity, which, but a few years since was looked upon as a philosopher's plaything, may now be fairly classed amongst the exact sciences.

So subtle is this force, however, so varied in its manifestations, so difficult to isolate from the influences of surrounding objects and forces, that some electrical phenomena are still but imperfectly understood, and an entirely satisfactory theory of electrical science has not yet appeared. Our instruments also, both for electrical measurements and for making use of electricity in practical operations, are in most instances still susceptible of improvement; and it is most essential that in the applications of electricity to military purposes, as in every other branch of military science, our army should keep pace with the discoveries and improvements of the day, and should be watchful, and ready to seize upon and weave into the web of that great and complicated fabric, the modern military system of civilised nations, every new scientific discovery which can be made to minister to the art of being the strongest.

The four special applications of electricity to war purposes to which I intend to draw your attention are—

1. The ignition of gunpowder.

2. The electric telegraph.

3. The electro-ballistic pendulum.

4. The electric light.

Electrical science has various other useful military applications, such as the protection of ships of war, and powder magazines, and other military buildings from the effects of lightning by means of the improved system of lightning conductors, for which the country is indebted chiefly to the researches of Sir Snow Harris; and the multiplication of copper plate engravings by an electro-metallurgical operation, which has been largely used on the Ordnance Survey. But such applications of electrical knowledge being in no way peculiar to the army, I will not allude to them further.

A safe, ready, and certain method of igniting gunpowder is of great value in numerous military operations. The circumstances under which it may be necessary to effect the ignition may be classed under two general heads. The ordinary service and proof of ordnance may be considered as one special branch; military mines as the other branch. Without alluding to small arms, we may be well satisfied with the friction-tube, as answering all the requirements of the artillerist, except in the case of the proof of ordnance, when for safety the operator must be at a distance, and electricity is advantageously employed. In this case there is a uniformity in the circumstances, and therefore a corresponding uniformity in the mode of operation, which may readily be reduced to a system.

The ordinary means of exploding mines, viz., "powder-hose" and "Bickford's fuze," cannot be considered as either safe or certain, and electricity may in most cases take their place with great advantage; but in mining operations the circumstances vary very widely, hence the adoption of one system becomes more difficult than in the former

case.

For instance, the powder may be in one charge or divided into a number of charges. It may be buried deeply under ground or under the water, or it may be placed in blast holes, or with but slight covering in buildings, to be hastily destroyed.

It may be necessary to operate from a great distance, or the electrical apparatus and operator may be placed in safety within a comparatively short distance of the mines.

In some cases the simultaneous explosion of a number of mines is of importance; and sometimes in this case the failure of one or two charges may be of little detriment.

In other cases it may be most essential to the success of some operation that one or two, or, it may be, a larger number of charges, should explode without fail, and probably at a particular moment.

There are cases again in which the miner may choose his own time for the explosion, and others in which the exact moment of ignition must be dependent on the uncertain movements of the enemy against whom the mine is directed.

Numerous other variations in position, number, time of explosion, and comparative values of certainty and facility in the operation, will occur, and a method of igniting gunpowder which is perfectly satisfactory in

all cases has not been discovered up to this time. While admitting this however, I must claim for electricity (whatever defects may still exist in our methods of applying it) that it is generally the most safe, certain, and convenient mode of exploding mines; and the only method by which we can ensure the perfectly simultaneous explosion of a number of mines, or the ignition of gunpowder at a distance at any particular moment, more particularly under water or in wet situations.

In confirmation of this, I may mention that at the commencement of the late demolition of the fortifications at Corfu, the electrical apparatus not having arrived from England, powder-hose was used for exploding the mines, and although every care was used, a number of the mines missed or hung fire; the latter description of failure being the more dangerous, as the fire sometimes smouldered for a quarter of an hour, and the mine exploded quite unexpectedly; moreover, perfectly simultaneous explosions could not be satisfactorily accomplished.

After the arrival of the electrical apparatus, the degree of certainty in the explosion of the mines was very greatly increased (amounting practically to perfect certainty in the case of the voltaic battery) the risk of hanging fire was entirely removed, and absolutely simultaneous explosions were effected without difficulty.

Before describing the apparatus by means of which sufficient heat for firing gunpowder may be produced by electricity, it will be necessary for me to put briefly before you the elementary principles of electrical science as now generally received. Electricity is now looked upon as one of the manifestations of the great force pervading all creation, which we call the attraction of gravitation, and of which mechanical force, heat, electricity, and chemical affinity, are but different modes of development, any one of which may be converted into any one of the others by proper treatment. Without attempting to define what this force with so many "aliases" may be, we know electricity, by certain accompanying phenomena, in two states, at rest and in motion, or static and dynamic electricity. A body statically electrified may be considered as having either more or less electricity than the earth, which is the electrical zero, just as with regard to heat the temperature of our bodies is our zero, and we speak of other bodies feeling cold or hot as they have less or more heat than our bodies, so a body is said to be positively or negatively electrified when it has more or less electricity than the earth.

And just as when two bodies at different temperatures are connected by a substance which will conduct heat, that which has most heat parts with its superfluity to that which has least. So if two bodies unequally electrified be connected by a substance which will conduct electricity, a flow or current of electricity passes from that which has most to that which has least, in the way which we call dynamic electricity.

The force compelling this transfer of electricity is generally known as electro-motive force, and it is greater or less in proportion to the amount of difference in the electrical states of the two bodies which are connected by the conductor.

All bodies with which we are acquainted, oppose resistance to this transfer of electricity, but the degrees of resistance offered by different

bodies are so very various that for convenience they are classed under two different heads-bodies which resist but feebly the electrical current, such as the metals, are termed conductors, while those possessing the property of resisting very strongly the passage of electricity, such as glass and resin, are termed insulators.

To understand rightly the action of electricity, we must have clear ideas of what are meant by the four terms-

Electro-motive force,
Electrical resistance,
Electric current, and

Quantity of electricity.

Electro-motive force is the active force tending to restore equilibrium when it has been disturbed, by causing the transfer of electricity, and overcoming the resistance opposed to this transfer.

Electrical resistance is what its name implies, the opposition or resistance offered by the substance through which the transfer of electricity takes place, diminishing the strength of the current, or the quantity of electricity which passes per second.

Electric current is the result of electro-motive force overcoming resistance, and we may generally reason about an electric current much in the same way as we do about a current of water.

We speak of quantity of electricity in the same way as of a quantity of heat stored in a body-e.g., the heat stored in a red-hot 32-pounder shot is a definite quantity, which would do a definite amount of work, such as converting so much water into steam, and producing so much mechanical force. So a definite quantity of electricity stored in a Leyden jar will do a definite amount of work in passing out of it in the form of a current or of a spark, by decomposing so much water, or producing a definite amount of heat.

A committee appointed by the British Association has been engaged for some time past in deciding upon certain standards for electrical measurements.

The unit of resistance has now been decided upon, with reference to the acknowledged units of mass, time, and space, and material standards of resistance may be procured, taking the place of the yard measure of length, in all electrical measurements. Standards of electro-motive force, current, and quantity, have also been provisionally decided upon; so that electrical measurements may now be made by proper instruments with as much accuracy as measurements of heat, or of weight, or of length, breadth, and thickness.

Let us now pass in review the electrical effects which are practically useful in military operations.

1st. The earth is a magnet; a peculiar ore of iron known as the lodestone possesses the same property; soft iron brought in contact with the lode-stone becomes temporarily a magnet, and steel permanently so. The north end of one magnet attracts the south end of another, and repels its north end, and vice versa, from which it will be evident that the end of a magnet which points towards the north pole of the earth is in itself a south pole, and not a north pole, as we are in the habit of calling it.