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terrestrial influence, when these bodies come swooping down upon the earth's atmosphere with a sun-generated velocity of nearly 24 or 25 miles per second, often superadded to the earth's velocity of 18 miles per second.

What could be gathered, then, from the great observed velocity of meteors would be inevitably this, that these bodies before reaching the earth had been travelling on paths far wider in range than the earth's orbit-that the aphelia (that is, the points of their orbit farthest from the sun) lay far out beyond the orbits of Jupiter and Saturn, perhaps even beyond the orbits of Uranus and Neptune.

In other words, although in one year the earth the meteors and the comet. Now it appeared
might cross the track of the meteors on or about that the path of the meteors (on the supposition
November 13, yet a long time after the path mentioned) accords most closely with the comet's
would have so changed that the earth would not path-so far, at least, as the parts of both paths
encounter the meteors on that date, but somewhat near the sun were considered.* The conclusion
earlier or somewhat later.
is obvious: an enormous weight of probability
favours the belief that the coincidence is not
accidental, but that, in some way (even now not
fully understood), the meteor system and the
comet are associated together.

Now astronomers might have waited for many years before they would have been able to verify the occurrence of such a change-but, fortunately, we have records of the occurrence of the November shower in long past years; so that all that was necessary was to compare the dates of those showers with the date on which the shower now takes place. The earliest recorded occurrence of But what amazing results would follow from star-shower belonging to what we now call the this! It would no longer be possible to regard November system, took place on October 12, meteor systems as in any way associated with A.D. 902, (or in the new style on October 18); and, the earth's orbit. We should no longer be able by comparing this with the date on which the to regard the earth's encounter with even a single shower now occurs (making due allowance for meteor system as otherwise than a most wonder- that peculiar motion of the earth's axis which ful coincidence, unless we concluded that besides causes the precession of the equinoxes), it appeared that meteor system there were millions on that the place where the earth encounters the millions of systems which lie altogether clear of meteors is steadily shifting forwards by about her path. And remembering that she encounters half a minute of arc in each year, so that a commany systems, we should have to abandon the plete revolution of the place of encounter could belief that a wonderful coincidence was in ques-be effected in about 30 x 360 or 10,800 years.* tion, and be forced to conclude that there must be countless millions of meteoric systems.

We shall see presently that the evidence is in reality even stronger than we are here supposing; but I do not hesitate to say that with no further evidence than the great observed velocity of meteors we should be led inevitably to the amazing inference that the solar scheme is crowded with meteoric systems. This inference would even then be no mere theory, but a legitimate conclusion from the evidence.

But astronomers have a liking for certainty. I am inclined, indeed, to say that they have too great a liking for certainty, inasmuch as they often neglect evidence which, though founded on the laws of probability, is yet overwhelmingly strong. At any rate, in this instance, it is certain that very little confidence would have been placed in the researches of Schiaparelli, had not a very surprising confirmation been detected shortly after his results were promulgated.

If the August meteors have their family comet, why not the November meteors also? And as the actual figure of the meteor orbit was known in this instance-which was not the case with the August meteors when Schiaparelli began his researches there was here a means of proving definitely that meteors and comets are associated, if only a comet could be found which travels along that particular route in space which the November meteors traverse.

But when Professor Adams-for the problem is one calculated to tax the highest powers even of mathematicians of his standing-came to examine the effects which the planets could produce on the meteoric paths, he found that this change of But no bright comets were found which could position was not accounted for on any of the be associated with the November meteors, and assumptions mentioned above. It became clear at first the search for faint ones was unsuccessthat the meteors are subject to disturbing attrac-ful. By one of those extraordinary coincidences, tions of a more effective character. In other however, with which the history of science has words, it seemed as though the meteors must familiarized us, a telescopic comet had but a travel out into regions where the giant planets, few months before been detected by Tempel, The occurrence of annual meteoric displays Jupiter and Saturn, or even Uranus and Neptune, the orbit of which (only calculated a few week had convinced all reasoning minds that the are capable of exerting more influence than they before Adams completed his labours) was found t meteors are cosmical bodies travelling on can exert on bodies travelling always near the to correspond very closely-or rather, in effect, planetary orbits around the sun. The matter earth's orbit. exactly-with the track of the November meteors. was in effect certain, though it was often spoken It was an obvious consideration that, this being Thus quite a new light was thrown upon the of as a theory, even by astronomers capable of so, the real period of the meteors is, probably, nature of these wonderful meteor systems. I appreciating the sound evidence on which it that same period-334 years or so-which sepa-pass over the later researches, which have shown rested. Another law of periodicity was to lead to rates the recurrence of marked meteoric displays that other well-known periodical meteor systems a further and even more important advance in belonging to this system. For with a period of are either associated with known comets or travel our knowledge respecting meteors. It was found 23 years, a body which along one part of its in orbits demonstrably eccentric. The two inthat one of the best recognised meteor systems-path crosses the earth's orbit, would along the stances above dealt with are quite sufficient to that which produces the November star shower-opposite path be far out in space, even beyond establish the important conclusion that the meteor waxed and waned in splendour within a period of the orbit of distant Uranus. systems are not in any way limited to the neighabout the third part of a century. In other The calculation of the motions of bodies travel-bourhood of the earth's orbit, but extend far out words, there was a rich part of the meteoric streamling in such orbits is by no means an easy matter. into space along orbits of the most eccentric which returned to a particular position in the solar Astronomers, though they often have to deal with figure." system once in about 33 years. But whether the motions of bodies in very eccentric orbits, yet it returned in reality only once in that period, or are seldom required to follow those bodies along oftener, was not certain. If it had come back to the whole course of such orbits, or to trace out the same position, but during another month than those processes of change which affect the position November, we could have known nothing about and figure of the paths of such bodies. it, for the earth would have been in another place." Astronomers were disposed to believe, in fact, that it did return several times in the course of the period of 33 years; for they could not believe that this rich region travelled out into space upon the enormous orbit corresponding to a

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It happened, fortunately for science, that a method devised long ago by the eminent German astronomer Gauss was available for the solution of this difficult problem. Adapting this method with singular skill to the requirements of the problem before him, Adams found that the changes

The consequences of this result are most striking, and have hitherto not received a tithe of the attention which they merit.

(To be continued.)

MICROSCOPICAL JOTTINGS IN TOWN
AND COUNTRY.
No. II.

E may now attempt the examination of our

revolution having so long a period. They ima- affecting the meteor's orbit are most satisfactorily W piece of cuttlebone, or as the learned call

gined that it returned to the place where the earth's orbit crosses the meteor track in about a year and a 33rd part, or in about a year less a 33rd part, and so came there at epochs passing round the circle of the months, either forwards or backwards, until after about 33 years the complete circuit had been formed, and so the display was renewed.

I shall now show how this view was shown by the great mathematician Adams to be unfounded, and the much more surprising results established that the members of the November meteor system have a period of 334 years, and travel out into space beyond the orbit of distant Uranus.

But, in the meantime, other and very remarkable evidence had been adduced which, at the same time, confirmed this result and proved that the August meteors also are travelling on an orbit yet more eccentric than that of the November meteor system.

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accounted for on the supposition that the meteors it, Sepiostaire. We will commence by dividing
really travel out into space along the eccentric bone" into halves across the axis with a
orbit which corresponds to the period of 334 years. stout knife. With a keen razor we can now cut
No doubt therefore remained, in the minds of with perfect ease very thin sections of the bone,
any who were capable of appreciating the evidence, and placing one of these on our stage, we find
that the path of the November meteors really that the bone consists of a great number of thin
carries them beyond the orbit of Uranus, or more plates, separated from each other by vertical
than nineteen times farther from the sun than laminae of excessive delicacy, which wind in and
our earth is.
about, reflecting upon themselves at intervals, so
as to form a better support for the plates. Many
have described these sinuous laminse as "pillars,"
but their true character is easily discoverable if
we make a careful horizontal section, removing
the "calcareous plate," so that the tops of the
so-called pillars may be seen. As "* opaques,"
these sections, when mounted on a black back-
ground, are very beautiful; but many persons
prefer to mount vertical sections in balsam, in
order that they may be viewed as polariscope
objects. The number of beautiful slides that
may be obtained from one piece of sepiostaire
would surprise the novice. The outer horny case
of the bone requires a different treatment, and
would hardly be adapted to the hands of a
beginner.

From the laws of gravitation it follows that when once the period in which a body travels The Italian astronomer Schiaparelli had been round the sun is determined, the velocity of the led to notice that the bright comet of 1862 passed body at any given distance from the sun is also close by the earth's orbit at a point lying very known, let the figure of the body's path be what near the spot where she encounters the August it may. So that the astronomer could determine meteors. Now that comet travelled in a very with what actual velocity the November meteors eccentric path, having a period variously estimated enter the earth's atmosphere on any given assump- at from 126 to 145 years, but undoubtedly very tion as to their period. This known, he could, by very simple processes of calculation, determine from the apparent direction of the meteor's motion as they enter our atmosphere, what is the actual direction in which they are moving at that part of their path round the sun.

And thus it became possible to determine, on each of the above assumptions, what is the actual path traversed by the November meteors. But then, given their path, we know what forces come into play to sway their path into new positions. And if their path thus changes, the place where the earth encounters them must change also.

long. It occurred to Schiaparelli to inquire
whether, on the supposition that the August
meteors travel on an orbit of like eccentricity,
their calculated path would lie near that of the
comet. It will be understood that the meteors
might cross the earth's orbit in a million different
directions, not one of which would correspond
to a path placed like the comet's—though of like
figure. So that the odds were enormously against
such a coincidence as Schiaparelli looked for,
supposing there were no real association between

*The real period is somewhat longer.

Before we leave, for a time at least, the sea*It is not to be therefore understood that the coincidence is not equally close for the whole of the two paths. But where we only have the opportunity of observing the part of a body's path which lies close by the sun, we are not able (unless very many and very exact observa. tions have been made, or unless the body has appeared more than once, so that we know its period) to determine very accurately the figure of the very remote parts oi the path.

By Dr. Peters of Altona.

diately the muscles of the mouth, of the back of
the throat, and of the larynx, &c., contract, and
shut out the access of any other agent than the
atmospheric air.

If an animal whilst plunged under water, is pre-
vented from coming to the surface to breathe, at
the end of a minute and a half it will appear to be
quite dead, and the jaws will be firmly contracted.
By keeping the mouth open, and causing move-
ments to be executed similar to those which are

side, we will glance at a few other objects that I
have secured at different periods. We may begin
with Polyzoa. The different species of Flustra
(sea-mats, &c.), found on all our coasts furnish
very good objects for the microscope of moderate
power-and be it understood that I shall speak of
nothing which a £3 3s. instrument will not show
well, with the exception of polarizing, which
would entail £1 10s. more. These must be care-
fully washed with fresh water, and then mounted
either as "opaques," or in section as "trans-produced in the act of respiration, the animal
parents," in balsam. I have one slide-a Flustra
foliacea, found at Hornsea, Yorks-which comes
out grandly by polarized light. This Flustra is
composed of small oblong cells; the base mem-
brane of this is seen studded with a vast number
of beautifully coloured crosses, which "rotate"
with the prism below the stage, when that is
rotated.

A parasitic Flustra, common on sea weeds, also furnishes a very pretty object for the inch objective. Of corallines, such as the "sickle," our shores commonly have an abundance; and these well mounted as opaques are not to be despised. Amongst the waifs of the shore we may generally find some very transparent crabshells, so transparent that they may be mounted "as they are,' in balsam, and submitted to examination. We shall find in them certain "wheel crystals" of lime, which are noteworthy as revealing to us one stage in shell construction. These two are splendid polariscope objects. The skin of the prawn affords better specimens of these circular crystals, but generally these must be got at the shops, and can hardly come into the category of sea-side objects. The sea hedgehog, or Echinus, is tolerably well known to most of our readers; yet probably few of them have paid it the attention that it deserves. Let us take one from our miscellaneous gatherings and give it a look over. The "Aristotle's lantern," being the jaws of the creature, may first attract our notice. The teeth which compose the jaw are five in number, and each "tooth has somewhat the form of that of the front of a rodent, save that its concave side is strengthened by a projecting keel, so that a transverse section presents the appearance of L.' The tooth itself is composed of carbonate of lime, and is in structure essentially the same as the shell; the keel is composed of cylindrical rods

64

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will recover life in proportion as the air pene-
trates into the lungs.

Dr. De Labordette tried this experiment on
twelve animals of the same age and species (viz.,
rats), with the following results:-nine were re-
stored, three died. But by prolonging the stay
under water to two or three minutes, the limbs by
degrees spread out, and the jaws were no longer
contracted. Of twelve animals which had been
immersed from two to three minutes, Dr. De
Labordette, not without difficulty, restored only
three: the others died.

The stiffness which follows death cannot be confounded with that which is produced in the subject whose stay under water has lasted only some moments. In the latter case, with subjects! restored to life, the rigidity is the result of the contraction of the muscles; in the other case it is due to the rigor mortis. Section of the medulla oblongata causes the first species of contraction to give way, but is without effect in the case of rigor mortis. Eight animals presenting, after a short immersion in water, a strong contraction of the jaws, were submitted by M. Legros and Dr. De Labordette to section of the medulla oblongata, and immediately the contraction disappeared.

The attempts to recover a drowned man from the state of apparent death ought to be so much the more persevering as the fact of the persistence of the contraction of the jaws is almost tantamount to a certainty of seeing them crowned with success. If, unfortunately, life is extinct, we have a sure sign of the inutility of any attempt at resuscitation in the spontaneous unclosing of .'" the teeth and the opening of the mouth.

SCIENCE FOR THE YOUNG.

(Continued from page 339.)
APPENDIX VI.

of carbonate of lime, having club-shaped ex- BY THE REV. E. KERNAN, CLONGOWES COLLEGE.
tremities," and the "concave side of the tooth is
coated with a firmer layer,' which some have
likened to the "enamel" of the teeth of verte-
brata. These teeth are furnished with delicate
serrations, visible by the aid of the pocket lens,

POLYGON OF FORCES.

and the whole apparatus is interesting in the N determining by composition the equilibrium

extreme. Around the jaws are a number of calcareous plates, easily removable, and to be mounted in balsam. These are interesting, inasmuch as they give a ready view of the structure of the shell and of the teeth. As polariscope objects, they too are good. The "spines" require to be sectioned, but though interesting, are not in our British species very remarkable.-H. P.

THE ACTION OF THE JAWS AND THE
PHARYNX IN DROWNING.

T is well known to most persons that by conrynx, and the roof of the palate, it is possible to prevent the entrance of air into the bronchi, and we are

enabled to plunge beneath the surface of the water, and remain there for some appreciable time. But it is not generally understood that, in the case of drowning animals, nature adopts this same method without effort on the part of the individual. Dr. A. De Labordette, after making numerous experiments on animals, believes that the contraction of the jaws, far from being a sign of death, shows rather the continuance of life; and he is strengthened in his conclusion by the fact that the Humane Society men, and all persons who have rescued and restored drowning persons, are agreed in declaring the existence of the contraction of the jaws. If we analyze the sensation which is experienced when we fall into water, we remember that we suffered for some time a vio

R

FIG. 71

of any system of forces, there is formed a polygon, which begins with one of the forces, continues by parallels equal to the other forces in order, and is closed by the final resultant. In Fig. 71, P1 P2 P3 P4 P5, are a number of forces acting on the point X. Combining P1 and P2, A there is produced the side Pl A, parallel to P. Continuing the combinations as in Law VI., there is produced: AB parallel to Ps, BC parallel to P, CD parallel to P, and DX closes the polygon. For equilibrium R X, a force equal and opposite to C X, is added. Therefore, this system of forces in equilibrium is represented by the polygon PA B C D X. Its sides being equal and parallel in order to the six balanced forces, show their relative intensities and direction. Such is the meaning of the "Polygon of Forces."

B

It does not signify, then, that the forces form a polygon, but they may be represented by a polygon, the sides of which show their direction and relative magnitude. It may be found enounced in other words, but these do not convey anything really different from what has been just stated.

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STRAIN. DISPOSITION OF FORCES.

It may sometimes be of great importance to know what amount of strain is exerted in certain directions in which circumstances require that the forces keeping a body in equilibrium should act. A polygon of the forces at once shows their relative strength of action on the body. The absolute value of one force being known, that of the others can be calculated. Again, a number of known forces are at command, it is required to know how they should be placed to hold a body at rest. A polygon with sides as the forces, show the direction each force should have.

APPENDIX VII.

"PARALLELOPIPED OF FORCES."

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As a polygon represents the equilibrium of a number of forces in (more or less) the same plane, so a solid figure with its diagonal represents a number of forces in several planes. The solid figure thus built upon the forces is called the Parallelopiped of Forces." The three sides of

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FIG. 73

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Fig. 73 are sufficient to give a good general notion of this important theorem. The forces P Q S, acting on a body at X, are represented in direction and in magnitude by the sides of the solid figure. A frame such as shown is clamped upon the table of Fig. 64 as the polygon in Fig. 72. Cords, with proportional weights, are disposed along the sides of the frame, Fig. 73. The diagonal-the dotted line, XX-shows the resultant. equal and opposite to the diagonal-the body at X is in equilibrium.f

Add the force R,

SUB-APPENDIX I.
PRACTICAL QUESTIONS.

Some interesting facts, and some most impor tant matters of every day utility, depend up the principle contained in the parallelopiped f forces. Were the subject not too difficult, the practical questions should be studied separser For the present little more than the indication of them can be given. I. Bellringers.-Large heavy bells require a number of men to make the

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swing. To on e large rope from the handle of the bell joined a set of smaller rope Fig. 74aa. How the me should stand, how pull, wher the stronger, where the weake should be placed, &c., can all calculated by the paralle piped of forces. II. Ships' ging. The general strain being known, it can be fairly cal culated where the greate strength must be in the rigging, lent constraint in the throat. We may swallow In the polygon A, Fig. 72, the sides are to one on the contrary, when, in case of storm, it how the various stays should be placed, & but not breathe, and when we come out of the and other as 4, 2, 5, 3, 1. This polygon (of wood) be required to "ent away," principles of cal water we still preserve for a long time the sensa- being clamped on to the table of the apparatus in culation will show where to cut, that the soures tion of contraction and constriction of the throat. Fig. 64, cords are disposed, Fig. 72 (from a ring, of danger be removed with all speed. I Let any cause or agent intervene to threaten the D, held by a pin to the wood), parallel to the Moorings.-The safety of all floating bodies,

For experiment, the theorem is reversed, "forces of relative magnitude, as the sides of a given polygon, are in equilibrium when acting upon a point if they be disposed in order parallel to the sides which represent their magnitudes."

respiratory function in its physiological condi- sides of the polygon, by means of the pulleys,
tions, the sensitive disturbance which the pneumo- on the frame.* Weights proportional, as 4,
gastric nerve receives from it instantly causes the
motor nerves-the spinal, hypoglossal, and the pulleys are nearer than they should be if the whole appa-
*The frame is omitted in the present figure, and the
laryngeal nerves-to enter into action, and imme-ratus were given.

*The figures at the weights show the lines to which the forces are parallel. Thus, 1 shows that the line is parallel to the side of which the length is one, c + Frames of any solid figure, acute angle, &c. &c., may be used as the rectangular frame of Fig. 73.

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ships' batteries, lights, &c., will depend upon the disposition of the chains and ropes which form their moorings. From the parallelopiped can be drawn the changes or additions which the ordinary run of circumstances may require. IV. Suspension bridges. As these are but little exposed to the action of violent unexpected forces, their equilibrium-conditions of security-as far as their concurrent forces are concerned, can be calculated with great exactitude by the parallelopiped of forces.

SUB-APPENDIX II. INSECT STRENGTH.

MECHANICAL MOVEMENTS.

The the steam to enter at the top, in the upper figure the relative strength of the forces is seen. effect of a c is to bend the nail, a d passes on to the exhaust is from the right end of the cylinder, the point e. There a d, transferred, decomposes and in the lower figure the exhaust is from the left again, say into e g and e h. If the nail point be not well fixed e g takes effect; if the wood can resist, e h has some small effect in sinking the point further. Many other possible decompositions of A B would show greater or less force, tending to bend or displace the nail.

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APPENDIX IX.

ROPES, CHAINS, ETC.

Thus far the applications of lesser importance. Now are to be seen (studied) some of the so-called 'machines," or "mechanical powers." Their most complete explanation depends only on the principles of force applied to a point. As the machines are of great practical utility, they shall be treated in four points. I.-What the machine

The utility of every sort of cord, rope, wire, Some time ago (1866) Mr. Felix Plateau pub- chain, &c., from the finest to the most massive, lished in the Bulletin de l'Academie Belgique arises from their being able to offer an equal and a most interesting series of papers on the strength opposite force to force brought to act upon them. of insects compared with that of higher animals.* It is "tenacity" which gives them this power up In this comparison of weight to work, Mr. Plateau to a certain point. found that while a horse can only do work equal to two-thirds of his weight, none of the insects are lower in work than four times their weight; some reach to 12, 15, 25, 42 times their weight. Mr. Plateau seems to have arrived at an experimental law, that their power of traction or of pushing is inversely as the weight and size of the is. insects. Granting the existence of great comparative muscular power, there can be no doubt but that the parallelopiped formed by the multiplication of feet, often armed with claws-curved claws-in many of the insect tribes, enables them to apply their power in a concentrated manner impossible to the horse.

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II. What is the principle of its action. III.-The conditions of equilibrium, established when possible by mathematical reasoning and formula. IV. The development-uses of the machine-and sub-applications. Even these have their applications, sometimes very important. They shall be distinguished from the general applications of the laws, by the name of the machine to which they belong.

MECHANICAL MOVEMENTS.*
(Continued from page 344.)

193. Contrivenical form. The polishing material

for polishing lenses and bodies

is in a cup connected by a ball-and-socket joint and bent piece of metal with a rotating upright shaft set concentric to the body to be polished. The cup is set eccentric, and by that means is caused to have an independent rotary motion about its axis on the universal joint, as well as to revolve about the common axis of the shaft and the body to be polished. This prevents the parts of the surface of the cup from coming repeatedly in contact with the same parts of surface of the lens or other body.

act along the line A B, the axis of the nail. Should it strike along AC the force is decomposed, part goes along A C, part along A B. Hence the endeavour to drive a crooked nail is a great waste of force, frequently having little more effect than to increase the crookedness. The study of this well-known fact affords an easy exercise in the decomposition of forces. The force of the hammer is shown in direction and intensity by the line A B, Fig. 76. That force 195. Four-way cock, used many years ago on may be decomposed into two; say one at right steam engines to admit and exhaust steam from angles to the axis (of the nail) a b, and another the cylinder. The two positions represented are along the axis a b. Completing the parallelogram produced by a quarter turn of the plug. Supposing *Extracted from a compilation by Mr. H. T. BROWN, Editor of the "American Artisan.'

Les Mondes, vol. i. p. 36, and vol. iv. p. 81.

194. C. Parson's patent device for converting reciprocating motion into rotary-an endless rack provided with grooves on its side gearing with a pinion having two concentric flanges of different diameters. A substitute for crank in oscillating cylinder engines.

thesteam entering, of course, by the opposite port. 196. G. P. Reed's patent anchor and lever escapement for watches. The lever is so applied in combination with chronometer escapement that the whole impulse given balance in one direction is transmitted through the lever, and whole impulse in opposite direction is transmitted directly to chronometer impulse pallet, locking and unlocking the escape-wheel but once at each impulse given by said wheel.

197. Continuous circular into intermittent rec

tilinear reciprocating. A motion used on several sewing machines for driving the shuttle. Same motion applied to three-revolution cylinder printing

presses.

198. Continuous circular motion into intermittent circular-the cam, C, being the driver.

199. A method of repairing chains, or tightening chains used used as guys or braces. Link is made in two parts, one end of each is provided with swivelnut, and other end with screw; the screw of each part fits into nut of other.

200. Four-motion feed (A. B. Wilson's patent), used on Wheeler & Wilson's, Sloat's, and other sewing machines. The bar A is forked, and has a second bar, B (carrying the spur or feeder), pivoted in the said fork. The bar, B, is lifted by a radial projection on the cam, C, at the same time the two bars are carried forward. A spring produces the return stroke, and the bar, B, drops of its own gravity.

201. E. P. Brownell's patent crank-motion to obviate dead centres. The pressure on the treadle causes the slotted slide, A, to move forward with the wrist until the latter has passed the centre, when the spring, B, forces the slide against the stops until it is again required to move forward.

202. G. O. Guernsey's patent escapement for watches. In this escapement two balance-wheels are employed, carried by the same driving-power, but oscillating in opposite directions, for the purpose of

counteracting the effect of any sudden jar upon a wateh or time-piece. The jar which would accelerate motion of one wheel would retard the motion of other. Anchor, A, is secured to lever, B, having an interior and exterior toothed segment at its end, each one of which gears with the pinion of balancewheels.

203. Cyclograph for describing circular arcs in drawings where the centre is inaccessible. This is composed of three straight rules. The chord and versed sign being laid down, draw straight sloping lines from ends of former to top of latter, and to these lines lay two of the rules crossing at the apex. Fasten these rules together, and another rule across them to serve as a brace, and insert a pin or point at each end of chord to guide the apparatus, which, on being moved against these points, will describe the arc by means of pencil in the angle of the crossing edges of the sloping rules.

204. Another cyclograph. The elastic arched bar is made half the depth at the ends that it is at the middle, and is formed so that its outer edge coincides with a true circular arc when bent to its greatest extent. Three points in the required arc

being given, the bar is bent to them by means of the screw, each end being confined to the straight bar by means of a small roller.

205. Mechanical means of describing hyperbolas, their foci and vertices being given. Suppose the curves two opposite hyperbolas, the points in vertical dotted centre line their foci. One end of rule turns on one focus as a centre through which one edge ranges. One end of thread being looped on pin inserted at the other focus, and other end held to other end of rule, with just enough slack between to permit height to reach vertex when rule coincides with centre line. A pencil held in bight, and kept close to rule while latter is moved from centre line, describes one-half of parabola; the rule is then reversed for the other half.

206. Mechanical means of describing parabolas, the base, altitude, focus, and directrix being given. Lay straight edge with near side coinciding with directrix, and square with stock against the same, so that the blade is parallel with the axis, and proceed with pencil in bight of thread, as in the preceding.

207. Instruments for describing pointed arches. Horizontal bar is slotted and fitted with a slide having pin for loop of cord. Arch bar of elastic wood is fixed in horizontal at right angles. Horizontal bar is placed with upper edge on springing line, and back of arch bar ranging with jamb of opening, and the latter bar is bent till the upper side meets apex of arch, fulcrum-piece at its base insuring its retaining tangential relation to jamb; the pencil is secured to arched bar at its connection

with cord.

208. Centrolinead for drawing lines toward an inaccessible or inconveniently distant point; chiefly used in perspective. Upper or drawing edge of blade and back of moveable legs should intersect centre of joint. Geometrical diagram indicates mode of setting instrument, legs forming it may form unequal angles with blade. At either end of dotted line crossing central, a pin is inserted vertically for instrument to work against. Supposing it to be inconvenient to produce the convergent lines until they intersect, even temporarily, for the purpose of setting the instrument as shown, a corresponding convergence may be found between them by drawing a line parallel to and inward from each. (To be continued.)

I'

WHAT IS ENERGY.

IN TWO PARTS.-PART I.

dually, and by very slow steps, the true nature of
work came to be understood. It was seen, for in-
stance, that it involved a much less expenditure of
energy for a man to carry a pound weight along a
level road than to carry it an equal distance up to
the top of a mountain.

it has the power of doing useful work or of over coming up to a great height the obstacle interd by gravity to its ascent, just as a man of gre energy has the power of overcoming obstacles. But this stone as it continues to mount upwards will d so with a gradually decreasing velocity, wutil at the summit of its flight all the actual energy wit which it started will have been spent in raising r against the force of gravity to this elevated positio It is now moving with no velocity-just, in fai beginning to turn-and we may suppose it to b caught and lodged upon the top of a house. Here then, it remains at rest, without the shigl tendency to motion of any kind, and we are led ask what has become of the energy with which 5, began its flight? Has this energy disappeared in the universe without leaving behind it any equiv lent? Is it lost for ever, and utterly wasted? the answer to this question must be reserved! another article.

It is not improbable that considerations of this
kind may have led the way to a numerical estimate
of work.
Thus, if we raise a pound weight one foot high
against the force of gravity we may call it one unit of
work, in which case two pounds raised one foot high,
or one pound raised two feet high, would represent
two units, and so on. We have therefore only to
multiply the number of pounds by the vertical
height in feet to which they are raised, and the pro-
duct will represent the work done against gravity.
The force of gravity being very nearly constant at
the earth's surface, and always in action, is a very
convenient force for this purpose; but any other
force, such as that of a spring, would do equally
well to measure work by. Generalizing, we may
say, the space moved over against a force multiplied ON THE RELATIONS BETWEEN BODY AN
into the intensity of that force will represent the
quantity of work done. So much for the definition
of work, and it is necessary to know what work is
before proceeding to define Energy.
Now what does the word energy mean? In the

first place it does not mean force.
Two substances may have an intense mutual
attraction, in virtue of which they form a very in-
timate union with one another; but when once this
union has been consummated, although the force
still continues to exist, the combination is singu-
larly deficient in energy. Nor does energy mean
motion, for although we cannot have motion with-
out energy, yet we may
motion.

have energy

without

By the word energy is meant the power of doing work; and the energy which a labouring man possesses means, in the strictly physical sense, the number of mits of work which he is capable of accomplishing.

This is a subject which at this stage we may attempt to illustrate by reference to a very different department of knowledge.*

The analogy which we shall venture to institute is between the social and the physical world, in the hope that those who are more familiar with the former than with the latter may be led to perceive clearly what is meant by the word energy in a strictly physical sense. Energy in the social world is well understood. When a man pursues his course, undaunted by opposition and unappalled by obstacles, he is said to be a very energetic man.

T is only of late years that the laws of motion By his energy is meant the power which he have been fully comprehended. No doubt it possesses of overcoming obstacles; and the amount has been known since the time of Newton that of this energy is measured (in the loose way in which there can be no action without reaction; or, in we measure such things) by the amount of obstacles other words, if we define momentum to be the pro- which he can overcome the amount of work duct of the mass of a moving body into its velocity which he can do. Such a man may in truth be reof motion, then whenever this is generated in one garded as a social cannon ball. By means of his direction an equal amount is simultaneously gene-energy of character he will scatter the ranks of his rated in the opposite direction, and whenever it is opponents and demolish their ramparts. Neverthedestroyed in one direction an equal amount is simul-less, a man of this kind will sometimes be defeated taneously destroyed in the opposite direction. Thes by an opponent who does not possess a tithe of his the recoil of a gun is the appropriate reaction to the personal energy. Now, why is this? A reply to forward motion of the ballet, and the ascent of a this question will, if we do not mistake, exhibit in rocket to the downrush of heated gas from its ori- a striking manner the likeness that exists between fice; and in other cases where the action of the the social and the physical world. The reason is principle is not so apparent, its truth has notwith- that, although his opponent may be deficient in standang been universally admitted. personal energy, yet he may possess more than an It has, for instance, been perfectly well under-equivalent in the high position which he occupies, stood for the last 200 years that if a rock be de- and it is simply this position that enables him to tached from the top of a precipice 144 ft. high it combat successfully with a man of much greater will reach the earth with the velocity of 96 ft. in a se- personal energy than himself. If two men throw cond, while the earth will in return move up to meet stones at one another, one of whom stands at the it, if not with the same velocity yet with the same top of a honse and the other at the bottom, the momentum. But inasmuch as the mass of the earth man at the top of the house has evidently the adis very great compared with that of the rock, so the vantage. velocity of the former must be very small com- So, in like manner, if two men of equal personal pared with that of the latter, in order that the mo- energy contend together, the one who has the imentum or product of mass into velocity may be highest social position has the best chance of sucthe same for both. In fact, in this case, the veloceeding. For this high position means energy city of the earth is quite insensible and may be dis-under another form. It means that at some remote regarded.

The old conception of the laws of motion was thus sufficient to represent what takes place when the rock is in the act of traversing the air to meet the earth; but, on the other hand, the true physical concomitants of the crash which takes place when the two bodies have come together were entirely ignored. They met, their momentum was caucelled-that was enough for the old hypothesis.

So, when a hammer descends upon an anvil, it was considered enough to believe that the blow was stopped by the anvil; or when a break was applied to a carriage wheel it was enough to imagine that the momentum of the carriage was stopped by friction. We shall presently alinde to the names of those distinguished men who have come prominently forward as the champions of a juster concep tion of things; but in the mean time let us consider some of those influences which served to prepare men's minds for the reception of a truer hypothesis, We live in a world of work, of work from which we cannot possibly escape; and those of us who do not require to work in order to eat, must yet in some sense perform work in order to live. Gra

* By BALFOUR STEWART, in Nature.

period a vast amount of personal energy was ex-
pended in raising the family into this high position.
The founder of the family had, doubtless, greater
energy than most of his fellows, and spent it in
raising himself and his family into a position of ad-
vantage. The personal element may have long
since disappeared from the family, but not before it
had been transmuted into something else, in virtue
of which the present representative is able to
accomplish a great deal, owing solely to the high
position which he has acquired through the efforts
of another. We thus see that in the social world
we have what may justly be termed two kinds of
energy, namely:-

1. Actual or personal energy.
2. Energy derived from position.

Let us now again turn to the physical world. In
this, as in the socia lworld, it is difficult to ascend.
The force of gravity may be compared to that force
which keeps a man down in the world. If a stone
be shot upwards with great velocity, it may be said
to have in it a great deal of actual energy, because

* The subject has previously been discussed from this point of view by Messrs. Stewart and Lockyer in an article in Macmillan's Magazine, August, 1868.

THE

MIND.*

(Concluded from page 342.)

HE different forms of insanity that occu young children-as all forms of it exp general paralysis may do-are almost always tra able to nervous disease in the preceding generati element in their causation. The cases of acut a neuropathic condition being really the essentie mania in children of a few weeks or a few years o which have been described might more properly b classed as examples of idiocy with excitement There can be no true mania until there is SOLE mind; but we do meet sometimes in olde children with a genuine acute mania, occurring usually in connection with chorea or epilepsy, and presenting the symptoms, if I may so express it, of a mental chorea or an epilepsy of the mind, but without the spasmodic and convulsive movements of these diseases. More or less dulness of intelligence and apathy of movement, giving the seeming of a degree of imbecility, is common enough in chorea, and in some cases there is violent delirium; but, besides choreic disorder of movements, there is a choreic these cases, there are others in which, without mania: it is an active delirium of ideas which is the counterpart of the usual delirium of movements, and its automatic character and its marked incoherence are striking enough to an ordinary observer. Hallucinations of the special senses, and loss or perversion of general sensibility, usually centres of special and general sensation, as well as accompany the delirium, the disorder affecting the the mind-centres.

Between this choreic mania and epileptic mania there are intermediate conditions partaking more or less of the character of one or the other-hybrid forms of a cataleptic nature. The child will he for hours or days in a seeming ecstasy or trance, with its limbs rigid or fixed in a strange posture. while at other times vague answers are given, or There may be apparent insensibility to impressions, incoherent raving. If this be of a religious kind, sudden bursting out into wild shrieks or the child is apt to be thought by ignorant persons to be inspired. The attacks are of variable duration, and are repeated at varying intervals. On the one hand, they pass into attacks of chorea; and, on the other hand, into true epileptic seizures, or alter nate with them.

there is

mania, a genuine mania transitoria, may precede,
In children, as in adults, a brief attack of violen
follow, or take the place of an epileptic fit; in th
latter case being a masked epilepsy. Children
three or four years of age are sometimes seized w
attacks of violent shrieking, desperate stubbornes
all the destruction they can; these seizures, wh
or furious rage, when they bite, tear, kick, and
are a sort of vicarious epilepsy, come on perio
cally, and may either pass in the course of a fe
months into regular epilepsy, or may alternate wi
it. Older children have perpetrated crimes of
even murder-under the influence of similar attacks
savage and determined nature-incendiarism. ar
of transitory fury, followed or not by epileptic
vulsions. It is of the utmost importance to realise
the deep effect which the epileptic
may have on the moral character, and to keep
mind the possibility of its existence when a savage
apparently motiveless, and unaccountable crime b
been committed. A single epileptic seizure he
been known to change entirely the moral characte
rendering a child rude, vicious, and perverse,
was hitherto gentle, amiable, and tractable. N
one who has seen it can fail to have been struck
with the great and abrupt change in moral cha
racter which takes place in the asylum epileptic
immediately before the recurrence of his fits: in the
intervals between them he is often an amiable,
obliging, and industrious being, but when they im
pend he becomes, sullen, morose, and most dan

Deuros

then foretell that he is going to have his fits, as gerous to meddle with. Not an attendant but call

* Two lectures delivered at the Royal College of Phy sicians in 1870. By HENRY MAUDSLEY, M.D., F.R.C.P. Professor of Medical Jurisprudence in Universit

College, Londor.

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confidently almost as he can foretell that the sun will rise next day. Morel has made the interesting observation, which is certainly well founded, that the pileptic neurosis may exist for a considerable period an undeveloped or masked form, showing itself, hot by convulsions, but by periodic attacks of mania, by manifestations of extreme moral perversion, Lich are apt to be thought wilful viciousness. Sut they are not-no moral influence will touch them: hey depend upon a morbid physical condition, which can only have a physical cure; and they get heir explanation, and indeed justification, afterwards, when actual epilepsy occurs.

fits, for evidence of an aura epileptica and other
symptoms allied to epilepsy.

the Croesor mountain, and runs downwards at an angle of 40° with the horizon; the purpose of this awkward incline being to get more quickly at that portion of the slate vein into which the company wish to quarry. The shaft is 8ft. high, and 10ft. broad, running through hard bastard slate very full of iron pyrites, and crossed by hard bands of quartz.

It is worth while observing that in other forms of insanity, when we look closely into the symptoms, there are not unfrequently complaints of strange, painful, and distressing sensations in some part of the body, which appear to have a relation to the mental derangement not unlike that which the epileptic aura has to the epileptic fit. Common The borer is shown in our engraving at work in enough is a distressing sensation about the epigas- the inclined shaft. The machine consists of a hori trium. It is not a definite pain, is not comparable zontal base, a a, coupled by four links with the strictly to a burning, or weight, or to any known motor (B)-an air-engine-behind it. Within the sensation, but is an indescribable feeling of distress base, a a, a horizontal shaft rotates, receiving its to which the mental troubles are referred. It motion through a pulley and belt from the fly-wheel sometimes rises to a pitch of anguish, when it of the engine. The vertical columns, c, cl, have abolishes the power to think, destroys the feeling of each a shaft revolving in their interior for giving identity, and causes such unspeakable suffering and motion to the boring tools, d, d1. The vertical and despair that suicide is attempted or effected. In horizontal shafts are coupled together by means of other cases the distressing and indescribable sensa- bevel gear, the followers being fixed upon the tion is in the crown of the head or down the spine, bottom ends of the vertical shafts, and the leaders and sometimes it arises from the pelvic organs. In running in longitudinal grooves cut in the horiall cases the patients connect their mental trouble zontal shaft, and being held in place by suitable with it, regarding it as the cause of the painful bridles. confusion of thought, the utter inability of exertion, the distressing ideas, and the paroxysm of despair. Perhaps they exaggerate its importance: but there can be little doubt that writers on mental disorders, too exclusively occupied with the prominent mental features, have not hitherto given sufficient attention to these anomalous sensations. We have been apt to class them as hypochondriacal, and to pass them over as of no special significance; but I cannot help thinking that, properly studied, they may sometimes teach us more of the real nature of the particular form of insanity-of its probable course, termination, and its most suitable treatment-than many much more obtrusive symptoms.

The epileptic neurosis is certainly most closely allied to the insane neurosis; and when it exists in its masked form, affecting the mind for some time before convulsions occur, it is hardly possible to listinguish it from one form of the insane neurosis. The difficulty of doing so is made greater, inasmuch is epilepsy in the parent may engender the insane eurosis in the child, and insanity in the parent the epileptic neurosis in the child. A character which the insane neurosis has in common with the epileptic neurosis is that it is apt to burst out in a convulsive explosion of violence; that when it develops into actual insanity it displays itself in deeds rather than in words-in an insanity of action rather than of thought. It is truly a neurosis spasmodica. Take, for example, a case which is one of a class-that of the late Alton murderer, who, taking a walk one fine afternoon, met some little girls at play, enticed one of them into a neighbouring hopgarden, there murdered her and cnt her body into fragments, which he scattered about-returned quietly home, openly washing his hands in the river on the way-made an entry in his diary, "Killed a little girl; it was fine and hot "--and when forthwith taken into custody, confessed what he had done, and could give no reason for doing it. At the trial it was proved that his father had had an attack of acute mania, and that another near relative was in confinement, suffering from homicidal mania. He himself had been noted as peculiar: he had been subject to fits of depression, been prone to weep without apparent reason, and had exhibited singular caprices of conduct; and it had once been necessary to watch him from fear that he might commit suicide. He was not insane in the legal or the ordinary sense of the term, but he certainly had the insane neurosis, and it may be presumed confidently that he would, had he lived, have become insane.

In bringing this lecture to an end, I may fitly point out how entirely thus far the observation of the phenomena of defective and disordered mind proves their essential dependence on defective and disordered brain, and how closely they are related to some other disordered nervous functions. The insane neurosis which the child inherits in consequence of its parent's insanity is as surely a defect of physical nature as is the epileptic neurosis to which it is so closely allied. It is an indisputable, though extreme fact, that certain human beings are born with such a native deficiency of mind that all the training and education in the Those who have practical experience of insanity world will not raise them to the height of brutes; know well that there is a most distressing form of and I believe it to be not less true that, in cousethe disease, in which a desperate impulse to commit quence of evil ancestral influences, individuals are suicide or homicide overpowers and takes prisoner born with such a flaw or warp of nature that all the the reason. The terrible impulse is deplored some- care in the world will not prevent them from being times by him who suffers from it as deeply as by vicious or criminal, or becoming insane. Education, any one who witnesses it; it causes him unspeakable it is true, may do much, and the circumstances of distress; he is fully conscious of its nature, and life may do much; but we cannot forget that the struggles in vain against it; his reason is no further foundations on which the acquisitions of eduaffected than in having lost power to control, or cation must rest are not acquired but inherited. having become the slave of, the morbid and con- No one can escape the tyranny of his organization vulsive impulse. It may be that this form of No one can elude the destiny that is innate in him, derangement does sometimes occur where there is and which unconsciously and irresistibly shapes his no hereditary predisposition to insanity, but there ends, even when he believes he is deterinining them can be no doubt that in the great majority of cases with consummate foresight and skill. A wellof the kind there is such a neuropathic state. The grounded and comprehensive theory of mind must impulse is truly a convulsive idea springing from a recognize and embrace these facts: they meet us morbid condition of nerve element, and it is strictly every moment of our lives, and cannot be ignored if comparable with an epileptic convulsion. How we are in earnest in our attempts to construct a grossly unjust, then, the judicial criterion of re- mental science; and it is because metaphysical mensponsibility which dooms an insane person of this tal philosophy has taken no notice whatever of them class to death if he knew what he was doing when because it is bound by the principle of its existence he committed a murder! It were as unreasonable as a philosophy to ignore them-that, notwithstand to hang a man for not stopping by an act of will a ing the labour bestowed on it, it has borne no fruits convulsion of which he was conscious. An interest--that, as Bacon said of it, not only what was asing circumstance in connection with this morbid serted once is asserted still, but what were questions impulse is that its convulsive activity is sometimes once are questions still, and, instead of being repreceded by a feeling very like the aura epileptica solved by discussion, are only fixed and fed." -a strange morbid sensation, beginning in some part of the body, and rising gradually to the brain. The patient may accordingly give warning of the impending attack in some instances, and in one case was calmed by having his thumbs loosely tied together with a ribbon when the forewarning

Each upright shaft has two (sometimes three) similar bevel wheels, each engaging with the corresponding wheel of a boring tool. With this arrangement the vertical shafts can at any moment be shifted horizontally-either brought together or se parated-by means of screws, e, e, working in suitable nuts fixed to the bases of the columns. The elevation of the boring tools can also be changed at pleasure, and they can be "angled" through any desired range; in one direction by the columns being turned round their vertical axes, in the other direction by the boring tools being turned in a vertical plane.

The boring tool is fixed at the end of a long screw, a nut upon which revolves with it, being connected with the driving gear by a friction clutch. The wheel which imparts direct rotation to the drill has one tooth more than that which presses against the nut. A differential motion is thereby obtained, which causes the boring tool to advance a certain distance with every revolution, unless the resistance which it meets in the rock becomes too great, when the clutch slips and prevents breaking the tool.

To avoid the heating of the drills by friction, and to lubricate them, a constant stream of cold water is kept flowing through them. For this purpose they are made hollow, and the water, entering through the elastic tubes, g, g, passes through the drill, during the time it is at work, and flows out of the bore through the space left between the diameter of the hole and that of the drill. The motor, B, attached to the boring machine, consists of an engine worked by compressed air, which is forced down the shaft through a gaspipe, D, D. This machine has to fulfil the double duty of working the drills and of pumping back the water which has passed through them to keep them cool and to lubricate them. The construction of this engine offers no point of novelty beyond the arrangement of the cylinder, which has the slide valve and the exhaust upon opposite sides in order to facilitate the clearing out of the exhausts in the event of their getting choked by ice formed by the refrigeration of water vapour upon the expansion of the air in escaping. The blast of cold air issuing from the exhaust of the motor thoroughly ventilates the shaft and keeps the air in it exceptionally clear and cool. Before the machine is raised or lowered in the shaft the two upper coupling links are drawn back by screws at the sides of the motor carriage upon which their lower ends are held. This causes the vertical columns, c, cl, to be tilted backwards until the base, a a, is brought to rest upon two hind wheels which run upon the metals forming the tramway as shown in the drawing.

The air which works this machine down in the shaft is compressed and supplied by a turbine in the DIAMOND ROCK-BORING MACHINE AT THE valley below; and this turbine is worked by a head of water conducted to it from a tank on the side of CROESOR SLATE QUARRIES. the opposite hill. The tank is fed from a small (Illustrated at page 378.) mountain lake which is perched among the hills high and provided with a sluice for the purpose. The the above the sea level, and which has been dammed up into which the lake-water flows is 350ft. above the turbine, with which it is connected by a 6in. castiron pipe. The turbine works a double action airpump, and the compressed air is conducted up to the inouth of the shaft through a 4in. cast-iron pipe, and from the mouth down into the shaft to the machine, through a 2in. pipe, till near the machine, where the connection is made with a flexible hose. This coinpressed air is applied to three purposes: it drives the borer, it pumps water out of the shaft, and it starts the hauling-up drum.

occurred. Dr. Skae records an instructive example in one of his annual reports. The feeling began at the toes, rose gradually to the chest, producing a sense of faintness and constriction, and then to the head, producing a momentary loss of consciousness. This aura was accompanied by an involuntary jerking-first of the legs, and then of the arms. It was when these attacks came on that the patient felt impelled to commit some act of violence to others or to himself. On one occasion he attempted to commit suicide by throwing himself into the water: more often the impulse was to attack others. He deplored his condition, of which he spoke with great intelligence, giving all the details of his past history and feelings. In other cases a feeling of vertigo, a trembling, and a vague dread of something fearful being about to happen, resembling the vertigo and momentary vague despair of one variety of the epileptic aura, precede the attack. Indeed, whenever a murder has been committed suddenly, without premeditation, without malice, without motive, openly, and in a way quite different from the way in which murders are commonly done, we ought to look carefully for evidence of previous epilepsy, and, should there have been no epileptic

Works of the Croesor United Slate Com-
recently had an opportunity of visiting the
pany's Quarries, in Carnarvonshire, and were much
interested by the process by which a new and diffi-
cult shaft is being driven into the side of the moun-
tain. Hitherto only hand labour has been em-
ployed for driving headings in these quarries; but
the necessity of pushing on some new work with
greater speed than could possibly be got by hand
labour, has induced the company to call in the aid
of the diamond boring machine, with the proprie-
tors of which, Captain Beaumont, R.E., and Mr. C.
Appleby, they have entered into a contract.
Amongst the various propositions which have been
brought into notice for machine tunnelling, one of
the most courageous and successful is that in which
a coarse cheap kind of diamond is used to form the
head of the cutting tool. Since the introduction of
the system, it has, of course, worked its way
through many stages before it arrived at being a
practical reality. The work it is getting through at
this moment, however, puts its capabilities to a trial
which cannot leave a doubt as to its efficiency.
The shaft which is being driven commences at an
elevation of some hundreds of feet above the foot of

The rope by which the loaded wagons are drawn up out of the shaft is worked on the tail-end system upon an opposite incline outside the shaft. The tail-end of the rope is attached to a wooden tank which runs down upon a tramway. When the wagon is down the shaft, the tank is drawn up under a shoot connected with a mountain stream which fills it. When full, its weight in running down its incline is sufficient to draw up the full wagons out of the pit. When it reaches the bottom of its incline, a valve in the bottom of the travelling tank is opened automatically and the water runs.

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