THE DUAL SYSTEM.

This System is so called because by it two symbols can be made to indicate any disposition of the four Cones. And it can be used with two different sounds, or two different visible objects.

The DUAL SYSTEM BY SOUND can be used with a Bell, Drum, Bugle, Steam Whistle, or other instrument, capable of producing a single sound, and two quickly repeated sounds. The single sound is used as a positive, and when made, represents a cone to be open, and may be denoted on paper by a X. The double sound is used as a negative, and when made, represents that the cone referred to is closed, and may be represented on paper by an O. Four successive positives or negatives complete a series or figure.

By using the fingers again for illustration, we have the code represented as before.

The application of the five auxiliary signs and of the Alphabetical numbers and pendants, is the same as in the Cone System, except the “Substitute," which is used only as an affirmative answer.

The" Preparative" and the "Stops," are repeated in reply, by the receiver of the signal, but the other sounds need not be repeated should it confuse the ear.

But great advantage is found both as regards celerity and correctness, by abbreviating the sounds for figures 1, 2, 3, and 4.

The figure 1, is denoted by a positive (single sound); figure 2, is denoted by a negative and positive; figure 3, is denoted by a positive and negative; figure 4, is denoted by two negatives and a positive.

The DUAL SYSTEM BY SIGHT can be used with any two different visible symbols, as a flag and pendant, or two different articles of clothing; or for a distant signal, a single pair of cones or sails; or for night signals, two different coloured lanterns, or a single and a double common light.

In the first case, the pendant may represent the positive, and the flag the negative, but where other articles are used without any preconcerted arrangements, it follows as a matter of course, as the "Pendant" must be made, that the article first shown above the other is the positive, and the other article the negative.

This system is essentially the same as that already explained for sound, the positive representing to the sight the open, and the negative the closed, state of the cone. And is also capable of considerable abbreviation, by omitting the negatives after the last positive in the series or figure.

For instance, let the two symbols (suppose a flag and pendant) be stopped on to the two different parts of the same signal halyards, so that as one goes up the other comes down, and the position of each may be determined by that of either.

Similarly in the DUAL SYSTEM APPLIED TO LIGHTS FOR NIGHT SIGNALS, one common light might represent the positive, and a red light or two common lights the negative, and both together the substitute.

With common lights only, the system as explained for sound might be used.

But with a red and a common light, the abbreviated system as explained for flag and pendant might be used.

The DUAL SYSTEM MAY ALSO BE USED WITH ONE SYMBOL in two different places, for instance with a ball on one masi, let the "up" be the positive and the "dip," the negative; tire, and at the Fore or Mizen be negative; or at night let or with a ball on two masts let the ball at the Main be posta red light above a stationary common light be negative and below the common light be positive.

Stop.

ག 0

་ 1

་ .

Telegraph.

ག 3

་

4

Geographical

་ 9

Interrogative. Compass.:

IMPROVEMENT IN SCREW SHIPS.

M. A. Normand, the well-known ship-builder of Havre, France, has patented in this country an im provement in the construction of screw ships. In carrying out this invention he says-and we give his own words, although they are not very intelligible:"To the part of the stern comprised between the two stern posts, on each side of the central plan of the vessel, and on' a proper extent, a segmental form, either convex or concave in cross section, or a plane surface, whichever will best suit the shape of the stern of the ship. Secondly, I close the bottom opening of the well-hole by sliding lateral doors or shutters (of wood, or metal, or both), taking the form of the outside of the vessel, and moveable either from within or from the deck of the vessel, so as to recede or approach each other. If thought desirable the sliding doors may be divided into several parts, and either worked altogether or separately. They may be opened or closed by means of endless chains, racks, and pinions, screws, or any other means found most suitable according to the size, form, and arrange ment of the vessel to which they are fitted. I also propose to alter the usual shape of the opening of the well-hole, making it follow the profile figure of the screw when viewed from the stern, the screw being turned to bring the central part of its blades into a vertical line, which is the position it will be required to take when it is raised or lowered. This novel arrangement has the advantage of reducing, as far as is practicable, the internal size of the well-hole, and consequently the surface which the sliding doors have to cover, and so give a greater length to the guides for the shutters."

The unsettled state of home and foreign affairs is reported to have exercised an injurious influence over Sheffield trade. A new rolling mill has, however, been started at Messrs. Hopper's Britannia Iron Works further north. Most of the India lines are using the conical-necked twisted railway spike which Mr. Hopper manufactures in considerable quantities. His works are now turning out about 1,000 tons of these fastenings.

In making Ships' Names, use "Stop" after ¶ with number of distant signal.

+ Nautical time (24 hours, from noon to noon) is used.

+ North being 32, N. by E. 1, N,N.E. 2, and so on.

THE CONSERVATION OF FORCE.

one body is equal to the momentum gained by the other. M. Seguin severely criticises mathe.

persons who cherish a lively faith in the common saying, "Brevity is the soul of wit." I participate in the antipathy which the illiterate feel towards long sermons, prosy lectures, and big books. Is this a proof of weakness? Does it show the man of low mental status if he prefer Emerson to Swedenborg-an express train to an omnibus-an article, in the Times to a German treatise on politics? My favourite principle is the principle of economy. I like to have ideas

communicated to me in as few words as are consistent with clearness of expression. It may be a proof of small intellectual endowments, but I must avow the truth-I have a disgust for the effort required to hunt a solitary forlorn idea through pages of verbiage as that needle has to be hunted for in a bundle of hay of which the proverb speaks. It may be that I am unequal to the necessary effort of attention, and therefore have failed to discover the great scientific truths which M. Seguin seems to think are expressed in his "Mémoire sur l'origine et la propagation de la force." This gentleman appears to be devoted to a law of economy just the inverse of that which I approve. His object is, one would think, having caught a stray notion, to load it with as much misty language as it can possibly be made to carry; and he is an accomplished professor of what Moliere calls,

"L'art de ne vous rien dire avec de grands discours."

A full analysis of this Mémoire would require more time than I can give, and more space than

you can spare. I will confine my attention, therefore, to M. Seguin's remarks on the subject. He

says:

"Take as an example, the attraction exerted by the earth upon a body falling from rest during a second of time; we know that, in this case, the velocity of the falling body, beginning at zero, gradually increases after the manner of an arithmetic series, till at the expiration of the second of time a velocity is attained such that if gravitation were then to cease to act, and the velocity were to continue constant, the body would move through a distance of ten metres every second. From this it is deduced that as the velocity of the body began at nothing and arrived at ten metres at the end of the first second, the nan velocity during that second was five metres; and therefore the body fell through a space of five metres in the first second. Further, as the velocity of the falling body continues to increase, the distance described by the body from the commencement of its fall, represented by the sum of all its velocities, will vary as the square of the velocity. Again, when two bodies, by virtue of mutual attraction, move towards each other the velocities which they acquire are inversely proportional to their masses. Hence it follows that if the number or the density of the molecules which form the earth were suddenly increased a thousand times, and just at the instant when a body is projected upwards with a velocity of ten metres, it would be reduced to rest after rising through a space equal to one thousandth part of five metres, or five millimetres, and the tire occupied would vary as the square root of the ratio

of the two masses."

Now let us suppose that the body, instead of losing in motion in whole or in part by the gravitation of the earth,

parts with it to some other body with which it comes into collision. It is evident that if the two bodies are not broken by the impact, they will undergo a mutual compression. The molecules of which the bodies are composed their relative positions. And as this requires a certain amount of force, the part of the force necessary to produce the compression of the body struck must be furnished by the impinging body. This body, then, must lose a part of it motion in the same way that it would if it had moved pression and communication of motions continue till the body striking has, according to its nature, exhausted all the motion which it is capable of transferring to the body on which it impinges. The two bodies will continue to move in the same direction, or in contrary directions, with the amount of motion with which the impinging body was previously endowed, diminished by any which may have been absorbed in separating the parts of the bodies, or in

will be forced to change their distances apart, as well as

for adopting the latter proposition. Now, it is my humble opinion that Poisson and the others are quite right, and that M. Seguin has fallen into a most transparent error. M. Seguin is quite motion apply to the collision of bodies as to their correct when he states that the same laws of motion under the action of gravitation. But herein he promulgates nothing new-nothing which would not, with perfect consistency, be assented to by any disciple of Poisson; for it is in accordance with these very laws that M. Poisson M. Seguin has conducted his investigation. adopts the ordinary account given of the fall of bodies under terrestrial gravity; and, therefore, agrees to the ordinary laws of motion. Of the two following equations he perfectly approves :— v = g t (1); v 2

s = \gt2 =

(2); 2g

Where v = velocity acquired in t seconds by a body falling from rest, s = space described in same time, and g the accelerating force of gravity 32.2 feet.

These equations apply to the motion generated in a falling body by terrestrial gravitation. They are not independent equations; for, either being given, the other can be deduced from it. These two equations are independent of the mass of the falling body, because terrestrial gravitation produces the same velocities in ali bodies falling from the same point during the same time. But, introducing the mass of the body, and giving the law which these equations express a general interpretation, they would stand thus:

=

I. Let M = mass of the body, P force in pounds acting on it and setting it in motion, V = velocity generated in time, t; and suppose m and to be the mass and velocity of another, acted on by the same force P, during the same time t, and under similar circumstances; then MV mv Pt;

=

that is, the momenta are equal.

II. Now suppose U and u to be the velocities generated in the two bodies by the same force P, acting through the same spaces; then we get MU2 mu2 = 2 Ps;

=

or, the vires vivae are equal.

It must be understood that M. Seguin by no means questions these two propositions, but he misapplies them. How he can have made this mistake I cannot understand, for it seems to me

that these two propositions, in conjunction with

the law of action and re-action, leave no room for mistake in the general treatment of the dynamical phenomena produced by the mutual action of any two bodies. For any kind of mutual mechanical action of two bodies on one another we have the two laws already cited, and the law that their mutual attraction or repulsion are equal in amount, but opposite in direction. It is quite axiomatic, too, that when two bodies exert any reciprocal action on each other, the bodies are subjected to the action during precisely the same time. Thus, when two bodies strike one

changing their form, or any which may have passed into

the form of light, heat, or electricity."

From this we are conducted, through more words than I care to attempt to translate, to the following proposition:

"The force which, during the impact, passes from one body to the other, follows the same laws which govern the motion of falling bodies; and the effects produced ought therefore to be measured by the product of the mass, and the square of the velocity."

That is, when two bodies impinge and undergo a change of motion, the vis viva gained by the one is equal to the ris vira gained by the other. The ordinary theory is, that the momentum lost by the

pressure acting during a very short period of time. But this small time during which the pressure acts is the same for one body as for the other. Hence equation 1, and not equation 2, applies to the collision of bodies, as it must apply to all mutual actions. Thus, in impact the impinging bodies are acted on in opposite directions by the same pressure during the same time. Hence it follows, from the laws which M. Seguin himself adopts, that the change of momentum in the one body is equal and opposite to the change of momentum in the other. The sort of case to which the second equation applies, may be illustrated by the stopping of a railway train by means of the break. If it be required to stop trains having various speeds within a given distance of the spot whereon the break is first applied, then the resisting force applied by means of the break should vary with the weight of the train and the square

of its velocity, or in other words with its vis viva. of two bodies, because in the latter, not the space But this is a case very distinct from the impact through which the impulsive force acts, but the time during which it acts is the same for the two bodies. If it were desired to stop the various railway trains within a given lapse of time after must vary as the weight of the train, and as the the application of the break, the resisting force first power of the velocity, or, in short, as the momentum.

His erroneous views on impact are not the only errors which M. Seguin's paper contains, but I shall spare all parties further reference to them at present. I am, gentlemen, yours, &c.,

A MECHANIC.

TELEGRAPHS TO CHINA AND AUS-
TRALIA.

TO THE EDITORS OF THE "MECHANICS' MAGAZINE." GENTLEMEN,-The immense field of commerce now opened to England in China, and the increasing prosperity of the British possessions in Australia, make it a matter of no small importance that the distance, in time, between China and England, and between Australia and England, should be diminished to such a degree as to afford merchants in China and in Australia better means of transacting business than they now have, alienated, as they are, from the electric world. We are promised, at no very distant period, an electric communication with Calcutta and Madras. It must be evident to every one who takes an interest in such matters that a comparatively small expense-to that of the Red Sea telegraph-would connect Calcutta or Madras with Singapore; Andaman's Islands forming a most convenient point for a "station," aided, if necessary, by a station on one of the Nicobar Islands. The distance from Calcutta to Singapore being about three-fifths the distance of the coast of Galway from America, all risk as to the laying of a cable is comparatively nil. The extension of the line to Hong-Kong or Canton, on one side, and a convenient point on the Australian coast, on the other, would soon be accomplished by the aid and eager co-operation of those who have interests at stake in those parts of our small earth. As you are never backward in publishing what may be of practical use to the community at large, I hope you will publish these suggestions from one whose means will, unfortunately, only admit of his investing hundreds towards the achievement of

such a scheme.

Atlantic Telegraph would now be in perfect workBefore concluding, I beg to remark that the ing order if steps had been taken to obviate the total want of longitudinal expansion, or elasticity. This could easily be done by placing, at distances (which should be regulated by the length of the cable and geodetic formation of its resting-place), conductive spring joints, which would add a little to the bulk and first outlay, but would ensure the wanted elasticity and success of the enter prise.

I have not been so statistical as I should have wished, owing to my being temporarily separated from references; but I shall feel some satisfaction I enclose my if my remarks are appreciated. card, and remain, Gentlemen, your obedient TIME IS MONEY. servant,

Vienna, March 31st, 1859.

His Majesty the Emperor of the French has pre sented Mr. Henry Bradbury with a magnificent gold snuff-box, surmounted by the Imperial crown and Mr. Bradbury's system of "nature printing." cypher in brilliants, in token of his admiration of

Experiments have been made at Vienna, Dresden, and other places in the use of tungsten or wolfram in the alloying of steel, and some extraordinary results are stated to have been achieved. It is said that steel alloyed with 20 per cent. of tungsten produces a mixture which, while it retains all the general made of it will cut, without difficulty, the hardest qualities of steel, is so excessively hard that tools cast steel. Large quantities of the new alloyed metal are said to be in preparation, and a company is about to be formed to work the discovery.

CAPTAIN FRANCIS FOWKE, R.E., who is well known as a scientific man, has patented the peculiar arrangement of portable fire engine which is represented in the annexed engraving, and which is capable of being easily transported either by manual labour or horse power, and forms a compact and powerful fire-engine, the ordinary wood or metal cistern hitherto employed being dispensed with, whereby the efficiency and lightness of the engine are greatly increased. "The improved engine consists," says Captain Fowke, "of a pair of single-acting force-pumps a, a, fitted with metal valves, and a suction and delivery air-vessel b, and to insure the proper action of the suction airvessel (not shown in the engraving) an additional

WE have been favoured by a friend with the following description of the nature and advantages of a new rifle-rest lately invented by Captain Connolly, R.N.; it was drawn up by the inventor. Captain Connolly, in this description, scarcely does credit to his simple and promising invention. The ramrod itself is employed to form the rest, by fitting it with a swivel radius pipe (frequently used for the ramrods of pistols). When the rod is pulled out sufficiently to release the end from the fixed pipe in the stock, it assumes a hanging position, as seen in Fig. 2 of the annexed engravings, and on lowering the rifle so as to allow the end of the ramrod to rest on the ground, a really efficient rest is provided for the piece. A socket, or cup in the stock, receives the upper or butt end of the ramrod, which adjusts itself to its and it is this simple self-acting principle work; which constitutes the beauty of Captain Connolly's invention. The following are Captain Connolly's

remarks:

This rest is made by a swivel screwed on to the lower part of the upper band of the rifle (vide sketch Fig. 1), the upper swivel, 4, being sufficiently large to give the ramrod full play, and being slightly ovalled if necessary, to fit flush into the stock when not being used and the ramrod is returned. A small brass cup or socket, large enough to receive the head of the ramrod, is let into the stock above the band the ramrod being then let fall through the swivel, and

RIFLE REST.

FIG. 1.

the head inserted into the cup, a most perfect rest is obtained.

It is by no means indispensable that the head of the ramrod should rest in the cup; it is nearly equally steady butting against the slings or any other part of the stock; indeed, for a sportsman firing from the kneeling position, it is better to slope the ramrod for ward, and let the head of it rest against the upper band. I merely insert the cup into the stock, because a small incision must be made to receive the swivel 4, when not being used, at the same time it steadies the

ramrod more, and makes the rest more perfect when the cup is used.

The advantages of this rest I conceive to be

1st. Its extreme lightness and simplicity, so that it is little or no encumbrance to the rifle, even should it not be used, as it would not be in close quarters, or on common occasions of skirmishing. Some men, indeed, would probably prefer never to use a rest; still I think even if twenty per cent. fire better with it, it is an object gained, and this rest is so exceedingly

men standing on it, their weight preventing the engine from moving. The wrought-iron frame h for working the pumps are fitted with swivel sockets i to receive the working handles, which are parallel with the axle when in use, and when not in use placed at right angles to it, being still supported by the swivel sockets, and serving as poles to carry the suction pipes. The fore-carriage

may be detached from the engine, and may con sist of a pair of high wheels k, mounted on an axle l, and suitable shafts m, with driving-seat #, footboard o, and box p, to contain implements. The axle may be fitted with a reel which revolves freely upon it, and on this reel the whole of the hose is coiled. When used merely as a hand engine, the fore carriage may be dispensed with, and the hose and implements placed on the engine."

light and simple, as to be but little encumbrance to the rifle should it not be used.

2ndly. I have observed in firing that it is in the elevation more than in the direction that most misses occur, from a habit some men have of throwing their heads back when firing, by which the piece is raised, or the act of pulling the trigger, however gently, causing the muzzle slightly to fall. Both these errors are entirely avoided by using the rest, for the muzzle resting entirely on its support, both hands are brought near the trigger guard, and the elevation, therefore, at all events, is not likely to be disturbed by the act of firing the piece.

3rdly. It is in long distances, i.e., from 600 to 900 yards, that a rest appears to me of so great advan tage, a man having to raise his head so considerably at those elevations, as to lose in a great measure the equilibrium of body which is assured by the present kneeling position.

I have myself found this to be the case; it was, indeed, from observing this great defect, and skir mishers being instructed to use every possible means of obtaining a rest at long distances, that caused me to turn my attention to this important desideratum in the rifle; especially as men are taught to form a rest, by inserting the screw end of the ramrod under the middle band of the rifle, with the head of it resting against the person; a plan, in my mind, as inefficient as it is dangerous to the soldier.

4thly. By means of this rest, a disabled man having the use of one arm can use his rifle almost with as much facility as with both, either in the stooping or kneeling position; a fact I submit of no small impor tance to the wounded soldier-in protecting himself, for instance, from marauders, who, however unscrupulous loaded rifle. in general in silencing resistance, would not face a

5thly. The expense of fitting the rest to the pretrifling, and if broken or impaired it is easily resent Enfields, or any other rifle, would be very placed, without injury to the rifle.

I repeat that I by no means wish to make it com pulsory that every man must use a rest; still I feel quite sure that there are many men who would at all times fire better with it; and for taking a deliberate aim, and at long distances, I cannot but think that nearly all would find it a simple and useful appen. dage to the rifle.

W. CONNOLLY, Captain, R.N. Bury-road, Gosport, April 20th, 1859,

R

A VERY curious apparatus, called an Automatic Injector, invented by M. H. Giffard, and made by M. H. Flaud, the well-known engineer of Paris, has recently attracted considerable attention amongst scientific and practical men in France. The apparatus has been adopted by the Director General of Naval Construction in France; and has already been ordered by more than one wellknown firm in the north of England.

The object of the apparatus is to supply water to the boilers of steam engines, or other steam apparatus, by means of the force of the steam contained in the boiler alone, and to return to the boiler all, or very nearly all of the heat contained originally in the steam thus used as the motor for supplying water to the boiler. It works without any aid from machinery; it is, in fact, perfectly automatic, as the title implies, and, consequently, it acts equally well when the steam-boat, locomotive, or engine to which it is attached, is in motion, or at rest.

A B is the pipe bringing steam from the boiler; CD another pipe or chamber which receives the steam from the former through the holes at Dthis latter pipe terminates conically; E F, small piston or rod working by means of a screw and handle, FM; this serves to regulate or prevent entirely the passage of the steam; G is a suction water-pipe. The water is drawn up into the chamber which surrounds the conical end of the steam pipe CD, and passes through the opening marked by an arrow between H H. The space left for the exit of the water is regulated by means of the lever and screw L, which moves the steam pipe, or chamber, CD, in either direction; IJ, is a passage to carry the water to the boiler, together with the steam which communicates to the water a portion of the force with which it is charged by the pressure in the boiler; O is a valve to prevent the return of the water from the boiler when the apparatus is out of work; P leads directly to the boiler; Q, is a screw stopper, to allow of readjust ment or cleansing of the valve; K is a tube which carries off any superabundant water which may collect in the space around; I R is an opening with a sliding corner, through which the action of the apparatus may be distinctly seen; the steam and water combined forming a continual and rapid stream between the parts I and I.

To work the apparatus-the diameter of the water supply pipe being calculated to give the necessary amount of water-the rod E F is moved forward by the handle M, until the conical end of

the rod stops the orifice of the cone. The steam cock in the pipe A B is then turned on; the screw handle M is then turned back a turn or so, to permit a small quantity of steam to pass. The steam in its rapid passage creates a vacuum in the chambers of the apparatus, and the water rushes up the pipe G into the space above. As soon as the water has entered, the handle is turned round so as to draw back the conical rod, and permit free passage to the steam; the water is then carried rapidly into the boiler, and ceases to run off by the discharge pipe K.

The principle upon which the apparatus is based is, that as the pressure is equal upon all the interior surface of a steam boiler, and consequently as each unit of surface sustains the same pressure, if the steam is taken from the boiler into the apparatus by a larger orifice than that through which it is returned, the force of entry of the steam will be greater in proportion to the dimensions of the two orifices; or, in other words, steam brought from a boiler through a pipe of a given diameter, can easily be forced into the boiler again through the other end of the pipe, provided it have a much smaller aperture. In the machine in question the entering orifice bears but a very small proportion to that of the supply pipe, because it is necessary to allow for the loss of force occasioned by the action of the water upon the steam.

In the above cut the apparatus is represented in a horizontal disposition, whereas it is now made vertical, but the only difference in the arrangement of the parts is the curving downwards of the two water-pipes G and K.

MR. JOSEPH WHITWORTH has just completed a patent for a set of improvements, which relate first, to a mode of giving accurate horizontal adjustment to a gun by moving its trunnions laterally in their bearings. This is effected by means of a lever which acts on one of the trunnions, the opposite end of the lever being connected with a screw which is adjusted by hand. To this apparatus, and mode of adjusting guns, the patentee makes no claim. Secondly, it relates to the use of discs or cakes of wax, tallow, or other similar lubricating compounds or substances, as wads for ammunition for ordnance and fire-arms, whereby the piece is properly lubricated. The lubricating materials may consist of bees-wax and tallow, used separately or combined, or of paraffine, or of such other similar substances as are not materially affected by being exposed to the action of the atmosphere. Mr. Whitworth has obtained good results from a composition consisting of equal quantities of wax and tallow; but the proportions may be varied according to the temperature of the weather and climate, care being taken that a sufficient quantity of tallow is used to ensure perfect lubrication of the barrel at low tempera

tures, while sufficient wax is employed to make the wad cohere, and withstand the effect of high temperature. Instead of mixing the wax and tallow together whilst both are in a melted state, he sometimes melts the wax, and runs it into a mould and when set pours the tallow on to the wax. In this case the tallow adheres to, but does not mix with, the wax, which thus forms a coating. In making wads for small arms, he takes a cake or sheet of the lubricating material made of the requisite thickness, and by means of a suitable punch cuts out of it wads or discs. Or the melted material may run in the form of a rod, and afterwards be cut into wads or discs. In making wads for large ordnance, he prefers to use moulds of the proper size and shape corresponding with the interior of the piece. The material is poured into the moulds, and allowed to set. Other modes of manufacturing, forming, moulding, or cutting the discs or wads may be adopted, but the simple methods explained answer well. Mr. Whitworth uses one or two discs or wads similar to those shown in end view in Fig. 1, and in section in Figs. 2 or 3. When two discs or wads are used, they may be of diminished thickness, one being