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as crystalline or amorphous. Crystals are those bodies whioh possess a symmetrical form, and are bounded by plane surfaces called faces. The Une formed by the junotion or intersection of two faces is called the edge, whilst the point formed by the junction of three or more faces is called the solid angle.

Axes are imaginary lines drawn through a crystal for tho purpose of facilitating the description of its geometrical properties and all crystals which can be reduced to tho same axes belong to the same system of crystallography.

There are six systems or distinct classes of crystals under which all known forms of crystals can be classed.

1st System.—Tho octahedral or regular system, called also the cubical system when the cube is considered tho typical form. If diagonals be drawn upon each face of the cube they will intersect in tho centro of each face; lines now drawn so as to connect the centres of each opposite face will give the axes of tho cube, of which there are three. The following minerals crystallize in the cubical or octahedral system :—

Zinc blende, alum, galena, silver, iron, salt, diamond, lead, gold, iridium, fluorspar, and iron pyrites. The crystals of this system exhibit only single refraction and expand equally in all direction.s when heated.

2nd System.—The typical form of this system is a right prism upon a square base, or an octahedron upon a square baso, therefore it is called the right square prismatic system; it is often called the pyramidal system.

If lines are drawn joining each face of a right square prism from the centre they will represent the axes, of which two, as they are formed in a square, must bo equal. Tho characteristic of the second system is three axes, two of which are equal.

Crystals of this system exhibit the phenomena of double refraction, but they possess one negative axis, i.e., one which does not possess this peculiarity. Tho following minerals are found crystallized in this system :—

Calomel, zircon, rutile, anatase, scheelite, and mellite. Tho crystals of tho above system expand equally in at least two directions.

3rd System.—Rhombohedral or Hexagonal System.—This system is characterized by possessingthree equal axes and one which is perpendicular to tho other three. The axes may be found by forming the hexagonal priem and joining the centres of the opposite edges, these lines are the threo equal axes; the other, and that which is perpendicular to the other three is found by joining tho centres of the hexagonal faces.

These substances crystallize in the 3rd system :— Calc-spar, quartz, bismuth, graphite, antimony, emerald, dolomite, ice, tourmaline, hmmatite, apatite, and amothyst. Double refraction and unequal expansion characterize this system.

4th System.—Prismatio or Rhombic.—This system, also called the right, rectangular or rhombic prismatic and orthotopic system, may contain crystals formed either from the prism or octahedron on a rhombic base. There are three axes peculiar to this system, no two of which are equal. The principal axis runs parallel to the long edges in the centre of the crystal; tho secondary axes are lines joining the centres of the opposite long faces of the crystal; they are perpendicular to the principal axis.

Cryolite, nitre, sulphur, topaz, citric acid, sulphate of zinc, and bichromate of potash, crystallize in this system. They possess two axes of no double refraction and expand unequally in three directions.

5th System.—The Oblique.—Tho typical form of this system is an oblique prism or an oblique pyramid upon a rhombic base. The behaviour of the crystals of this system under the influence of light and heat is similar to the preceding system. The principal axis runs in the centre of the prism, parallel to the oblique long edges, joining the two rectangular faces. The secondary axes join the centres of the long faces. In this system two axes are oblique, and the third perpendicular to both.

The following crystals belong to this system:— Carbonate of soda, malachite, sulphate of iron, sulphate of cobalt, gypsum, felspar, Glauber's salt, mica, and realgar.

6th System.—Doubly Oblique or Anorthic System.—This system may be called the orystallio lumber-room : it is the system to which all crystals are referred when they cannot be classed in any of the preceding systems. Most of the forms of this system are characterized by then' want of symmetry: they possess three axes, all of wliich intersect each other obliquely, no two there'oro are inclined to each other at right angles.

The following crystals belong to this system :— Sulphate of copper, nitrate of bismuth, native boracic acid, axinite, and Labrador felspar.

A chemical compound generally crystallizes in one form belonging to one system, but some ore found to crystallize in two forms, they are then termed dimorphous: as an instance, calcium carbonate is found as arragonite in the prismatic system, and as calc-spar in the rhombohedral system.

Common salt generally crystallizes in cubes, but if deposited from a solution containing urea, the form is altered to that of an octahedron; and sal ammoniac, treated likewise, is said to form cubes instead of octahedrons, which it always furnishes in pure water.

Certain bodies when they take the crystalline form acquire a certain amount of water, which is neoessary for the permanence of that form; when this water is expelled the crystal falls to powder, it is therefore ceiled tho water of crystallization.

When orystals dissolve in water, the bulk of this latter fluid is not increased if the crystals be anhydrous; if such, however, is not the case, the increase is only by the amount of crystallization water they may contain. From a vast number of experimeuts upon the subject it is probable that hydrated crystals when in solution exist, not as a solution of the anhydrous salt, but as one of the hydrated crystals. A solution of sodium sulphate saturated at 32-78° С with the ten-atom hydrate, upon elevating the temperature, about one-sixth of the salt is deposited as anhydrous rhombic ootahedrons. If a supersaturated (boiling) solution of sodium sulphate is made, and the vessel closed to oxclnde nuclei, it may remain for a long time before crystallization sets in, but if nuclei are admitted in the shape of dust, or if touched with anything surfaced with that which is foreign to its composition, it at once solidifies (see Nature, Aug. 4; Chemical Neirs, xxii., page 560). But before we leave the subject of crystallization we will notice one point which has had such influence in the progress of chemical philosophy.

Substances are termed ùomorphoun when they crystallize in the same system, with an identical or but slightly different angular element, or when they are found intermixing with other eubstanoes without altering their form.

Mitscherlioh has shown that bodies which possess an analogous constitution,exhibit also a similar crystalline form. Of this we have an instance of the manganese, chromium, aluminium, and iron alums. These alums possess the same crystalline form, and the sesqui-oxides of the above metals are termed isomorphons.

If wo examino a crystal of magnesite (carbonate of magnesium) we find it belongs to the rhombohedral system ; calamine or zinc carbonate belongs to the same system, and the angles vary but a few (15) minutes ; therefore, by the law of Mitscherlich the oxide of magnesium is isomorphons with the oxide of zinc, and the two compounds possess an analogous constitution. Magnesium carbonate is Mg" С 0-¿, and zinc carbonate is Zu" С Од. Calcium in calc-spar, iron and manganese in the proto-salts, with nickel, cobalt, and copper, form with the above what is termed an isomorphons group. Acids also form isomorphons groups, as—1st, phosphoric acid, vanadic acid, and arsenic acid; 2nd, sulphuric, chromic, and manganic acids; while molybdic and tungstic acide arc also isomorphons.

As an instance of the control of formule by the law of isomorphism, I may quote the recent researches of Professor Roscoe on the subject of the true atomio weight and constitution of the salts of vanadium. Beraelius assigned the formula V Oj to the acid oxide ; but Karamelsberg, a few years afterwards, observed that vanadiitite ((Pb Cl2) + (Pb 0)j + (Pb3 (V Ot\) was isomorphou? with apatite ((Ca Cl Fl) + C¿3 (V 04)a), and with mimelile ((Pb СЩ + (Pb, (V 04)2), and it was then supposed that anhydrous vanadic acid had au analogous composition to the arsenic and phosphoric anhydrides, viz., V2 05. Nothing was done in the matter till Professor Roscoe took it up and thoroughly investigated it. The result of his experiments was, that the vanadium trióxido of Berzclius turned out to be a pentoxide, and th( lower oxides exactly agreed with those of phosphorus. From the above experiments, which we rei »lit say proceeded from Jlitscherlich's law of isomorphism, vanadium has been placed in its proper pliicj among the metals, and its true atomic weight established.

[To be continued.)

A PRACTICAL TREATISE ON THE
HARMONIUM.*

By Hermann Smith.

(Continued frota page 458.)

THIRD DIVISION.-CHAPTER VI.

OF THE RESONANCE OF THE CHANNELS.

Л musical note, far from being a répétition of the вягас simple sound, should be considered as the conjunction of subordinate- sounds reiterated at proportional intervals. Tho sweetness of this Compound effect or tone appears to depend on the frequent recurrence of interior unison.—Prof. Leslie.

A MUSICAL pipe is of true or perfect longth when it is capable of maintaining pnlsations which synchronize with the vibrations of the exciting agent. The unison is integral and absolute. Nevertheless there may be many departures from this perfect condition whioh shall be agreeable to the ear; minute divergences which seem to waver on either side the balance, and variations to a range apparently beyond the governance of the same laws, remote from tho same system of tones. An organ would be a very tame and spiritless aflair if ail its pipes were of perfect standard, and so likewise would tho harmonium be if we sought only to use one perfect scale of channels; indeed we consider the principles of the organ and the harmonium to be in all particulars identical. Each instrument helps to explain the other. The pulsations of a pipe have no dependence whatever on sound; they exist prior to it, have a dynamical causation, of which sound is the accumulated effect. The power of transmitting the force is inherent in tho constitution of air. This you should bear in mind, that air, being an elastic fluid, must of necessity vibrato or pulsate whenever it is disturbed, even as water is under necessity, in like condition, of gravitating in a series of undulations until it attains equilibrium. If the surface of water is disturbed it is ruffled into waves; of these the eye takes cognizanco by means of the intervals of lights and shadows. In analogous modes the results of the elastic force which is active in the air when under disturbance, affect the ear as sounds by reason of its power of estimating the intervals of pulsations. We throw a stone into a lake, and it produces an annular wave; we see the circle expand and spread farther and farther until it subsides into quiet, all its impulse absorbed in the mase of water. It is the same when tho air is stricken; it is agitated to undulations which epread and die away in the ambient expanse. If those air-waves have certain periodic times with quick repetition or deflnito rates of velocity, they become, to our perceptions, music. You should think of the condition of tho air quite apart from its musical effects. The condensations and rarefactions of air under impulso constitute wave-motion.

Advance now a step further. Confine water in a trough; at one end agitate it, raising waves, these will spread, will travel to the opposite end and not cease there, but return with rebounded impulse.moeting and crossing over other oppositelyadvancing waves. In like manner if air is environed, enclosed in pipes, pulsations excited will be returned and rebounded ; but the waves of the condensations and rarefactions of air differ in this, that they have definite lengths and a celerity of motion of which water can give but a faint representation ; for air is a free ocean surrounding us, and its ratio of elasticity is constant, whereas, in comparison, water is elastic only on its surface. Analogy should not be forced too far: it has its limits, else it would be identity.

The perfect pipe of which we have spoken would be the flue-pipe of an organ. This class of pipes is always regarded by builders and philosophers as being of a nature quite distinct from the class of pipes called reed-pipes. As briefly setting forth the doctrine, we note tho following passage by Dr. Bushnan :—" In the flute, flageolet, and diapason organ-pipe the molecular undulations of the air are the source of musical sounds."

And again, Dr. Brewer, in his work on Sound, speakiug of reed instruments and reed pipes, says :—" They differ essentially from those (viz., flute and organ pipes). In the former the column of air i* only the auxiliary of the sounding body, in the latter it is the sounding body itself.'

Our views do not coincide with these, which we believe to be erroneous. We may not stay now to refute them, but can only ask you to take note of tho divarication as essential to the full understanding of tho statements we have to placo before you and the arguments to be founded upon

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tUcm. No column or body of air is itself capable of sounding or of creating sound; it is always au auxiliary—a resonator, and nothing more. We hold the organ pipe and the harmonium channel to be both resonators. The difference is one of degree only, not of kind, and through all the varieties of pipes and channels we trace but one determining clement, the relations of proportion. Thus the full-length eight-foet organ pipe is active in giving simple or integral resonance, the diminutive channel is active in giving multiple or lesser resonanoe. And what is resonance? If we ask, with a child'e persistency, whatis resonance? why does resonance increase the power of any tone ? text-books and teachers sagely tell us it means "sounding again," or they tantalize with merely formal explanations, which fail to reach the root of the inquiry. The best elucidation we know of is to be found in Brande's " Dictionary of Science and Art." "Resonance.—In music a very indefinite term need in regard to the production or reverberation of sound." Admirably true, for the idea called np by tho use of the term resonance is generally as vague as this explanation. Let us hopo to obtain a little light at all events on the physical fact we want to express. Evidently the word is wrong; looking to its philological derivation it is seen at once to be inadequate, for we want to express the condition which produces the musical result. The term is naturalized in science and cannot be displaced. It is, however, necessary for the development of our argument that we should define clearly what we mean by " resonance." Let us coin a word for the occasion. When we say a pipe or channel is resonant we would affirm a physical fact, that it is re-undative, that it returns the wave.

We will halt here and bring up the line of argument with which we started to rejoin at this point. The exciting agent at the mouth of a pipe has a periodic time of movement wherewith the column or body of air, by reason of the perfect accord of its wave-length, responds in faultless synchronism; the two movements meet together in time, or absolute unison. Imagine now that this double-natured pipe affords a parallel to the nature of two notes of a musical scale. Thus, two notes from two distinct musical sources may be sounded, and being of the same pitch, they sound the unison. We spoke of minute divergences,—yes, the tuner well knows that they boar very considerable passage below or beyond absolute unison before they become discordant: yet mark this, the minutest change cannot be effected without producing appreciable difierenoe in the quality of the combined tones. If instead of the unison we combine the octave, the wave of which is as two to one, we perceive a new result. In some kinds of organ pipes we obtain the parallel of this, cither by diminished length or by forcing the wave-lengths to break up into lesser waves when we elicit harmonic relation or multiple resonance; hence also channels of length, capacity, and proportion, accordant with the multiple pipe, return the wave with similar synchronism, even as a fifth, or third, or fourth synchronizes with the fundamental note of a chord. Strike the notes of a chord in succession and you can recognize them again as regards the quality of the tones as well as in their pitch. Strike the same notes as a combined chord and we feel that the tones have coalesced into something very different in the effect or display of quality ; tho blended or compound tone is a new product. A change in characteristics, as of substances when brought anew into chemical anion. It may be for better or for worse. We often experience this in harmoniums ; one that will render a melody pleasantly will become intolerable as soon as the notes are thrown into combination for harmony, and on the other hand an instrument of real artistic worth will so blend in its harmonies with infinite variety in effects of quality, piquant flavours, glimpses of tonal colour so alluring, that the ear is never satiated with its charms, but finds new beauty, new delights, day after day. The same peculiarities are observable in organ pipes and channols; according to the relation of proportions in the associated generator and resonator, so is tho result affecting the ear: some pipes of simple resonance aro soft and agreeable, others tame and dull; some pipes of complex resonance and full of harmonics, are harsh and jangled and almost unbearable, others are rich in lovely qualities. What a compound of harmonics in the tone of the French horn, yet what tone more captivating to the musical ear 1

We recognize three states of resonance : the integral resonance, or simple undulation of the whole —the diminished or multiple resonance—and the

combination of the two into one system, or compound resonance. Resonance may be manifested in two modes: when the generator and resonator are allied, their activity being reciprocative and supporting, as in organ pipes, reed channels, and musical instruments generally; and the second mode,when the generatorand resonator are isolated, detached, and merely sympathetic in response, as is the case with musical vases, hollow soundingboards, and the like. In whatever mode manifested the physical action is the same, giving back the wave—re-nn dative.

The question remains, why resonance increases the power of tones? The re-undulated impulse, provided it is timed in concurrence with the stroke of the generator, produces an augmentation of sound by reaction upon the agent, thereby increasing the amplitude of its vibration (intensity of tone depending npon amplitude), and by receiving that strengthened energy upon a larger area, and again propagating the impulse of an increased surface upon the external mass of quiescent air. Resonance is to the generating sound an auxiliary in actual force; the arrow flies faster with the wind. It conspires to aid the original impetus, just as on the stage the springboard aids the vaulter to increase the amplitude of his leap, timed as the swing of the rope to the hand of the trapèze performer; musical vases are as springboards to the wave-tones that leap upon their aerial surfaces. The organ pipe and the harmonium channel differ only in degree, the one superior in extent of surface, the other inferior in the front it can present to act upon the external air. With your fingers you can agitate the air inferiorly, but take a fan in your hand, and you communicate your impulse by the presentment of a superior extent of surface with an enormous increase of power. Thus it is with the organ pipe; its larger orifice and more capacious mouth are the endowment of a giant, as compared with the diminutive scale and little apertures of the harmonium channel. The resonating power of the organ must, therefore, always transcend the capabilities of the harmonium. In a former chapter we illustrated the shapes of the channels; we have now to set forth the scales or dimensions of the channels. Experiment tells us that when channel of about 18in. in length is allied to a reed of 16ft. tone we obtain the best quality of sound that reed is capable of affording. Now we cannot well use such a basis for the scales of the harmonium, or we should occupy almost as much space as with an organ, and have to adopt a similar system in building. No doubt a smoother bass wonld In gained and better balance of tone, for at present the tenor and bass are shorn of their just pro portions, in order to economize space, and henc< the roughness orreediness preponderates, drown ing the treble, unless great skill is exercised to restrain it within due bounds. The structure of the harmonium is compatible only with a system of reduced scales, and we can but select the best and be content with the compromise.

Scale M, 8ft. tone.

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In general reference we may denote scale M as suitable for flute stop; scale N, for bassoon stop; scale O, for diapason stop; these are the three usual 8ft. stops included in full-sized in s tri; ments. Scale P, for the fife stop, or principal 4ft. tone ; scale Q, for bourdon or double diapason stop. Yet it muet not be forgotten that before we can pronounce definitely what quality any particular scale of channel will yield, we have to consider the character of reeds, the sizes of apertures, the influence of pallets, and other details. Therefore, be not too curious about precise scales and absolute measurements, for should you copy a maker's plans yon will not of a surety attain results equal to his, unless you could follow his methods throughout up to the final finish of the work. Your teacher may be lavish in expoundin" his special knowledge, and in giving the fruits of experience and study, yet there is a skill which is incommunicable, and even figures cannot reach the minuteness which only moulds of each channel could adequately supply. Each maker has his own particular set of scMes, to which he clings with partiality, and henos his instruments bear features by which they are recognized in comparison with instruments of other makers who use different scales. Excellence is of many degrees. To work out new scales a man needs to be patient in observation and sagacious in inference, sensitive to perceive quality in sounds, and eager to analyze the combinations conenrrimr to produce the ultimate effects. Looking at the variations of channel, each said to respond to 8ft. tone, there seems to be little appearance of law or system; all looks casual and arbitrary, yet experience, the surest teacher, leads us to very different conclusions. The scales for the apertures, which will be given in the next chapter, exercise a most important influence, and rest on principles deeply involved in the physiology of the voice, although practically disregarded by manufacturers who disdain study. It is so much easier to rely upon custom, tradition, and rule of thumb. Our anxiety has been to interest you in the principles which govern the quality of sounds. Our next most necessary consideration relates to the vowel qualities reed tones, and the effect of apertures thereon; the subject, originally investigated by Kratzenstein, and afterwards by Prof. Willis, of Cambridge, yields to nono in value for the student of the harmonium.

In a passage in the last chapter the word "larynx," was inadvertently allowed to pass, when obviously the word "trachea" should have been substituted.

(To be continued.)

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ELEMENTARY SCIENCE.«

By The Rev. E. Kernan, Clonoowes Colleok.

(Continued from page 633.)

Application X.

Inclined Plane.

NOW studying the action of a common ecre? in water, observing its defects, and correctif these by the aid of the " consequences," the etndent will find himself face to face with the propeller as described in tho first point.

It is clear that a screw placed in water will work a nui for itself, as a common wood-screic does in a piece of timber. The defects of a common screw working in water aro four in number. To each defect let its remedy be applied; the remedies are to be found amongst the "consequences." Taking at once an examplo, suppose a screw of which the " elements " aro measured thus: "pitch " {in., " breadth " of thread Jin.

Defect I.—Yielding Of The Water.—The liquid state being so movable a form of matter, the resistance is far from being equal to that of the solid state. Hence the screwwith '■ elements' as above would produce little or no motion, the small quantity of water which touches the threaJ of the screw would yield to the force concentrated thus in a small space.

Cokeection I.—The "thread " of the screw is

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spread out, from being ^, to (say) 5ft. in breadth. The forco now divided over a large surface being much diminished at the parts which make np that surfaoe, the water in contact with theso parts is able to resiet,—the screw acts, the body joined to the screw moves.

Defect II.—Small Advance.—Tho height of the inclined plane—the pitch of the screw—being so small (Jin.) the body only moves Jin. at each turn. The velocity therefore should be something incredible for any useful effect.

Correction II.—The " pitch" of tho screw is increased, say from Jin. to 16ft. At each turn the body will advance 16ft. In Fig. 99 is represented

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one turn of a screw of great pitch.

Defect III.—Waste Of Space.—With the extended "pitch " there are large spaces—from A to В and nnder the two end-portions, С, C, of the shaft, Fig. 99—in which there is no work done. The work then is not so much divided as might be, and consequently the action on the pooriyresisting water is greater than need be.

Cokkection III.—An Archimedean screw of 1, 2, . . . n threads is substituted for the screw with only one thread. The spaces А, В, С, C, of Fig. 99 are filled up by a second spiral, or " thread," in Fig. 100. Two being enough for the most complete

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explanation, it were better not to render the diagram confuse;! by more spirals. The work being thus much more divided, the water at tho different parts is much better able to resist, as the whole amount of resistance (suppose to be the samo as before) is now divided over a much larger area. Theoretically, therefore, it ought to be possible to make a screw so that the water should offer complete resistance, and consequently the ship should advance at each turn to the full pitch of the screw. Experience, however, showed that there was still an unthought-of defect.

Defect IV.—Motion Of The Water.—Practically it is found impossible to avoid setting the water in motion. The resisting power of the wator is so small, that only a part of the screw finds a "nut" immovable for a moment. Quickly this " nut " receives the rotatory motion of the screw, which motion destroys all resistance to the remainder of the screw. Besides this neijative effect, the moving water has a positive retarding action upon the inefficient part of the screw. Supposo that tho space С В, Fig. 100, represents the "working part" (as it may be called) of. the screw; and that the ship bo moving in the direction of the arrows a, a. All the resistance of the water is overcome in that space С В, and besides the remainder С A having nothing tt, work against as it advances into the moving water, it is opposed by the backward motion of this water, which produces a current in the direction of the arrows b, b, which current strikes the entire remainder of the screw. Even were there no retarding current, tho remainder of the screw would be a drag upon the ship's progress.

Correction IV.—As every portion of the screw acts independent of the rest, "cut off the useful part." The discovery of this correction was the result of an accident, and seems to have preceded the knowledge of the defect. In the early experiments, the screw of one of the first ships was partly broken. To the surpriso of all concerned,

tho consequence of the injury to the Bcrew was increase of speed. This fortunate accident led to a series of experiments as to tho real useful length. Piece by piece tho screw was shortened, each cut giving improved speed, until about l-6th of a turn was reached. Here seemed to be the limit, and it is pretty generally admitted that about l-6th is the efficient part of the screw. Let the student now imagine a plane cutting off l-6th of the screw. Fig. 100; the cut-off piece is the propeller, such as was first shown in Fig. 94. As it is almost impossible to give a clear, correct, perspective view of the "cut" by a side view,

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Fig. 101 represents the double spiral turnod for an end view. The cutting plane А В is seen full front, and exhibits the identity of the cut-off piece with the propeller Fig. 94. The plane ie supposed transparent, and shows {through) one complete convolution of the double spiral. The apparatus of Fig. 100, being made with one piece movable, removes every difficulty there may be of clearly understanding the screw-action of the now so important propeller. The question "What is the screw propeller?" may now be answered in a few words. "It is a portion of an н-threaded screw." This portion is every day receiving new forms, to meet new minor defects, or to suit peculiar circumstances; and in some cases, although the action still continues to bo that of the inclined plane, there is a deviation from the outline of the strict screw, or "true screw," as it is called. Much as this important subject has been studied, there would seem still to be considerable difference of opinion amongst practical engineers, even as to its most important elements. The question is much complicated by the form of the ship, the currents running to and from the screw, &c. On theso points further detail would here be out of place.

(To be continued.)

THE FLUTE AND ITS VICISSITUDES.

By. Sable.

(Continued from page 459.)

The Revolution Of Böhm.

FEW instruments have passed through such reverses in the conrso of reconstruction as the flute, and certain it is that no other has suffered so severe a penalty; and if it is not wholly consigned to oblivion, it is treated with a coldness and neglect as uujust as it is undeserved. The pianoforte and violin are not more popular now than was the flute in the days of the Nicholsons and the Ashes; a concert then without a flute-solo would have been quite as unorthodox as the absence of a violin-solo at the present time, and it always elicited an equally hearty and well-merited encore. Our periodicals teem with notices of musical doings; musie was never more cultivated and appreciated by the public generally than at this period; new artists and new music appear as regularly as tho flowers, and are welcomed with an unfailing interest: but we look in vain amidst the names of those who distinguish themselves as instrumentalists for a flautist—soloists there are in goodly array, but the voice of praise once raised forthe "silver-toned" flute is heard no longer. And why is this? Has all love and admiration of the instrument died out? This little couplet, from the pen of a popular writer, says "nay."

"Her volco ....

So Bolt it was, and liko tho note

Yon olttimes hear npon the flute."

And the flute's voice was never sweeter than

now; the old "breaks" which formerly somewhat disfigured its evenness are to a great extent removed, and all its time-honoured beauties stand out in greater prominence. Whence, then, the semi-contempt with which it is regarded, even by professors themselves? A greater reproach to tho musical world could scarcely exist than the systematic manner in which this elegant and once fashionable instrument is ignored. Is it that further experiment and alteration ar¿ fearcd? That apprehension is groundless ; both players and manufacturers have had enough of that, and to spare, if vexation, anxiety, and loss are good preceptors; he would indeed be reckless who should adventure more time and money in so "used-np" an undertaking. It is certain that all professional players have now come to a sort of growling understanding as to the flute of thoir adoption, and that, and no other, will they recommend to their pupils.

It is both useless and foolish to cushion facts, even though they be disagreeable. The flute is a very difficult instrument to play thoroughly well; it has difficulties inherent to its nature; but so has every other instrument, and it is by conquering these that the student gradually emerges into the professor, and it is by deeming this conquest always imperfect that the professor arrives at distinction. Mr. Chapman (p. 469), writes as a master; his observations are the result of experience; the road to proficiency is rugged, albeit the personal aid of one like himself will render the rough places much smoother and pleasanter to pupils. A great deal is advanced about the difficulties of the extreme keys, but the real difficulty is more often to be found in the composer, and that in what are called the easy keys. It is worthy of remark that perhaps the greatest cause of the flute's neglect lies in the lukewarmness and want of energy and industry both of composers and professors. There were giants in "flutedom" in days past—why should there not be again? Whatever man has done, man can do, and greater means are now at his disposal.

The flute was what we hope to seo it again. Its popularity as a source of recreation and enjoyment was unrivalled, but it was soon to bo exiled from the drawing-room, driven from its position as a solo instrument, to become henceforth chiefly the occupant of the workshop aud orchestra. As it had engaged admiration aud regard, so also it engaged the eye of the critic ; its defects were pointed out and enlarged upon, the necessity of a reformation was spoken of, and ere long it was commenced with a vengeance,—it was stripped of its charm and simplicity, and what it gained in its resources and importance it lost in public favour. The defects of the eight-keyed flute lay chiefly in the cramp fingering for F natural. There was a difficulty in passing from octave to octave with freedom ; there were some awkward cross and back fingerings ; its tone was unequal; some notes were rich and full, others very dull and feeble. There is an obstacle, common to all instruments of its genus—as the oboe, clarionet, bassoon, &c.— which tho flute presents to the learner,!, е., passing from the last fundamental note to thefirst note of tho octave immediately above, which often involves the simultaneous movement of all the lingers; this can never be completely removed, although it is now materially obviated. True it is that the access from С sharp to the D might be rendered perfectly easy, but it would simply be transferring the evil to the next note, and in that case the D (now a good note) would be harsh and thin in quality. The violin has its own peculiar difficulties, and tho alteration of the distances in the "stop "in the different " positions" on the finger-board, commonly called the " ehifts," may be included among the greatest of them; but if the violinist will put all his four fingers down on a string, and keeping them well down, do a rapid even shake with tho little finger, he will realize something of the finger-gymnastics of tho flute. This is had enough; but let him replace all his fingers, and keeping the rest duwn try to execute a shake with the third finger, and ho will experience the pleasant sensation inseparable from tho anatomical arrangement of the tendons of this finger employed under such embarrassing circumstances. On referring to the drawing at page 459 it will be seen that two keys, a and b, are provided for the little finger of the left hand (Ü sharp and F natural) ; the use of the latter is sometimes very awkward and perplexing; to the right hand little tinger are apportioned the three foot keys ; the reader will thus вее the labour imposed npon the weak digits. One other koy only claims notice in this flute, the long С natural, manipulated with tho first linger of the right baud. Ou looking at the finger-holes it will be seen that they are unequal iu size and irregularly graduated, henoe the nnevenuess of tone and flatuess of the third octavo, because those holes which serve for vent holes in the production of the latter are frequently too small for the purpose. To finger A natural in the third octavo every aperture is closed with the exception of 1 and 6, these are very small holes, therefore, the note is fiat, thin, and requires great strength of lip to render it well in tune and agreeable to the ear. For E natural in this octave all the holes are closed save 3 and 1; it is true that the D sharp key is open, but this does not materially remedy the evil which results from the smallnees of tho two holes actually engaged in tho delivery of the noto. In the formation of the fundamental E natural 6 is the hole uncovered, with the addition of the D sharp key, and the result is a dull feeble note. "Any pipe constructed to emit a musical sound must contain within itself a medium of resistance, and thus give an additional impulse to the vibrations of air as they pass through it." Glancing again at the engraving, it will bo noticed that the body of the flute is conical, the diameter of the bore at the foot joint being about one-third less than at tho head (in tho flute from which the sketch is made it is only one-fourth loss, which perhaps accounts for the fulness and beauty of its tone). Bat this conical bore offered rather more resistance than was needful, preventing the flute from "speaking freely," and causing that difficulty in " getting out " the lowest notes with which amateurs are so painfully familiar. To remedy this defeot and equalize the position and size of the holes was the study of HerrBiihm.aprofessorof Munich. In the year 1728 a Captain Gordon, residing in Paris, laid the foundation of the system. It occurred to him that if the handle of a key covering a distant hole was brought in a semicircle round the edge of a finger-hole above, tiro holes could be stopped by tho action of one finger. Herr Böhm sent the first practioal model of this flute into England about 1832, and it was protected by letters patent. The fluto now changed the form of its body from a cone to a cylinder. It was thought this would render.tho fundamental octave more full and free ; shut keys wore changed into open keys, the bore was equal ill diameter throughout, the holes were enlarged and made equal in size to remedy the inequality of tone and tune. The following is quoted from a treatise on the subject by the patentees :—" Equality of tone can only be obtained by means of cqual-iized holes." This is only another way of saying, take an organ pipe suitably graduated in length and diameter for the correct delivery of its proper noto, say tenor C, cut it in half, place it in the wind chest, and it will givo you tho octavo above. So it will, if double force of wind be used; but tho note will be harsh and disagreeable, and out of tune, because the diameter of the pipe is not proportional to its length. Never was any fallacy so perversely held as that of equalsized holes. To obtain greater freedom in passing from octave to octave the fingering was changed and all altered. The key arrangements were entirely remodelled, and rings we»e added to give the power of acting on holes now placed beyond the reach of the proper fingers. In the next paper drawings will be given of the Böhm flute. It was intended to give illustrations of the several forms which the instrument has assumed, but when it ia stated that during tho years 1818 and 1849 those eminent flute makers Messrs. Rudall & Rose manufactured ten flutes for different schemers, all of which were during that time discarded, it will be admitted that the space and tunc of the engraver are capable of better employment. The names of these instruments are barely remembered : they were acoustical, scientifical, and mechanical, but they could not rescue them from oblivion, and nothing remains of them save a few odd drawings and descriptions.

In the Nicholson flute the natural fingering only has been alluded to, i.e., that which gives the best tone and tune. No reference is made to the "exceptional" fingerings, as they are only used to facilitate rapid continuous passages, brilliant effects, Sic, and are quite inadmissible in the sostenuto.

(To be continued.)

Tbc Phenüphthaluiotropeis tho паше of a now machino for elucidating tho movement* of the eye-ball. Its inventor is Dr. Dondurs, of Utrecht. By its help, the mathematical analysis made by Prüf. Uehnholtz of the ocular movements may he prActically demonstrated.

THE PROGRESSION OF LIFE. *
(Concluded from page 535.)

IT is the same with the animal kingdom. The whole, the unity which it presents to ns, involves the life and death, the genesis, the maturity, the decline, not only of an infinite number of individuals, but also of n vast number of species and families, which once having disappeared are never reproduced. They too manifest in their evolution the same law as each individual, the phases of whose existence have conspired to form their distinctive character. And not only in so far as each stage in their development, also, is inseparably liuked with the preceding one, but in this too, that the whole coarse of that progression at any period is portrayed in the changes which one individual, that shall be taken as typical of the progress of the species, undergoes in the course of its own growth. Crustaceans, as we have said, present to us, in their complex organizations, the highest type at which the life of the earth hod arrived at the close of the Silurian and the beginning of the Devonian epoch ; but they were preceded by vast numbers of individuals, whose abnormal forms were for a long time a puzzle to geologists. But in the mature form of many of these we now recognize the larvallike organization of those higher crustaceans which succeeded them. "Almost all the genera of Trilobites," says Agassiz, "seem to be the prophetic images, ш a gigantic form, of'the different types the Crustacea present in their embryonic state."

Again, the insect type isa more highly organized one than the crustacean ; and1 it is much later, in the carboniferous epoch, that we obtain the fossilized forms of true Insecto. But insects are divided into two great classes—those which have an imperfect, and those which have a perfect, metamorphosis ; and through a series of strata, representing a vast interval of time, the forms and species of the lower class are abundant, while those of the higher are scarce to be found.

Further, organisms that are recognized as fishes become noticeable at the commencement of the Devonian epoch. But in what order do fishes, as a class, come into the world? Taking one of the most highly organized fishes, such as it exists at present, and noticing the changes it undergoes in its development, we find that the growing embryo has a vertebral column of cartilage before it develops a perfectly osseous one; it has a one-lobed tail before a twolobed one -, the position of the mouth is lower in the embryo than in the mature form. Looking at the species of fish now existing, we put those with a cartilaginous ekeleton, as the sturgeon, lower than those with a bony one ; the one-lobed tail is considered a mark of lower organization than the two-lobed one, and the inferior mouth is held to he a characteristic of less perfect forms. But for thousands of years in the history of the world cartilaginous fishes were the predominant, the only forms, that peopled the seas. The characteristics of the heterocorcal tail and the inferior mouth are here almost universal. It is not until the Chalk era thai the forms which give a specific character to the fish-type of the present come into significance. So that, in the words of Agassiz, " the embryo' of a fish, during its development, the class of living fishes in its numerous families, and the fish-type in its planetary history, go through analogous phases." The embryo of a frog is, as we know, to all intents and purposes, a fish, and iu geological order, Fishes, as we have seen, precede Batrachians. One of the characteristics of the true reptile is that the vertebras are different from those of amphibiu, which have more resemblance to the bi-concave ones of the fish, and we have seen how huge Amphibians represented vertebrate life on the globe before the appearance of true Reptiles. But man also, as the head of the mammalia, gradually assumes the specific characters which distinguish him from all other beings; passes through certain transitional stages in which are sketched as it were, in rude outline, the permanent forms of those types of animal organization which are held to be lower than his. That is to say that, commencing his existence in a germ similar to that in which every form of existence has its rise, he develops successively points of resemblance to the fish, the reptile, the bird, and the annual. Moreover, as we have said, the yonth of the civilized man has much in common with the matured character of individuals of less civilized races. And, looking at the forms of life which have successively distinguished the epochs of the developing world, this is the order, this the general plan, in whieh with advancing time they have gradually insensibly assumed more and more complex phases. "Nature," says Sydney Smith, " has not formed man totally different from other animals, but rather added to bis brain new organs. She has not, in his case, pulled down the fabric of sentient being, and reconstructed it npon a totally different plan. All that she has done has been to add to the original edifice Corinthian capitals and Doric columns ; bestowing reason, not to supersede, bat to guide, direct, and perfect his animal nature." The whole course of the world's history has been

* From a troatise entitled " Force v. Organization/ in St. Cutlibert's Magazine.

an uninterrupted evolution from tho first moment to this last. The first forms of existence implied the life that was to follow, as the child is father to the man. That life was potential then ; it is actual noa. The character of the fut tire forest is involved in the molecules of tho first acorn. "Das Weltall ist ein Gedanke Gotten"—the Universe is a thought of God. And seeing how this life-scheme of the globe has " unhasting and unresting," through unnumbered centuries, followed the appointed path; how, in spite as it were of the agencies that have lifted or submerged continents, that have destroyed myriads of individuals or wrought strange effects in the forms that succeeded them.—how, notwithstanding the ravages of earthquakes and tempests, the conflicting forces of fire and of deluges that have made or marred the surface of the globe,—that- globe has fulfilled the stern decree of its destiny; ha» solved in the growth of every germ and in every moment the problem of all its existence, we cemrtot but regard that existence as the embodiment of a thought, that growth as the realization of an idea.

Fuit her. the whole life of the human race ii one which comprehends not only those lesser cycles completed in the life and death of all those human beings that have lived and died since the first appearance of man until now, but also involves а number of those larger cycles which have their beginning and their end in the rise and decay of nations; and in these we may perceive, in like manner, the growth and decay of families and tribes.

But the laws of the existence of the social organ ism is, as we have seen, the same as that of the vegetal and animal one. They too are gradually evolved from simple, crude beginnings to the most complex phases of their organization. "Progress, therefore, is not an accident, but a necessity. Instead of civilization being artificial, it is a part of nature—all of a piece with the development of the embryo and the unfolding of a flower. Tho modifications mankind have undergone, and are still undergoing, result from a law underlying the whole organic creation."*

If, again, there be " one mind common to oil individual men ;" if " the genius and creative principle1 of all eras" is to be interpreted by, because involved in, the mind of that individual who shall best embody the genius and resolte of his own ; il the epochs in the development of the race have their counterpart, аз we have said, in the years which make up the life of one man. and the tendency of great civilizations, Jewish, Egyptian; Greek, Roman, &c, be read in the thoughts and aspirations of childhood, youth, and manhood, then does hnman life become the key to the whole history of the world; the lav:s uf the- human mind become embodied, in the facts and systems of the, geologist, a* toell as in the facts and epochs of Iwman history ; then must the course of man's development invoice tket principle* of all developmenttehaUeerer.

Now, we do not wish to shnt oar eyes to the difficulties which he ill the interpretation of the great problem of the development of life on the globe. We know fall well all that may he urged against our generalization; but it is became we Ktinw these things, because we perceive that there ¡ire a multitude of iacts seemingly more irreconcilable with it than any we have ever seen stated, but which we trnst to show are in accordance with it, that we have put it in the way we have done. We have transferred the great problem of the genesis and development of life in all its forms to that of human life, as the microcosm which involves the principles of all. But ore there no difficulties here? Has humanity no problems left unsolved in that which concerns itself, its oten life, its own development?

Allowing that the development of life on the globe has been a continuous evolution, as we affirm, yet the method of this progression must not be misunderstood. It does not imply that the highest forms of one class ore intimately related to the lowest forms of another ; that if Invertebrates preceded Vertebrates, or Molluscs Crustaceans, in the order of the developing life of the globe, in such manner as we have stated, our theory by no means demands that the highest Invertebrate should give rise to the lowest Vertebrate, the highest Molluscs to the lowest Crustacean. In considering the progress of civilization, the Roman succeeded the Greek, as we English have come after the Roman, but this does nut imply that the lioman was developed fron the Greek, ur that the Englishmtm is a lineal descendant of the Roman. They each take their rise from distinct centres. The ancestry of each may be traced back to a remote past ; and the predecessor of the Roman was contemporaneous with the ancestors of the Greek of the age of Pericles, and the ancestor» of the Englishman oí the nineteenth century with the age of Augustus. It is precisely the same with the history of animal life. In what remote past the ancestor of the exogenous plant or of the verte brate animal may be discovered, it is left for science to determine. *

Now, the same law holds good even of the differ- • eut species of any class. Take that of the Mollusca, for instance. One, perhaps, that comprises at pre

♦ H. Spencer. X

zalion which it gains in it* development, au equiva-
lent of¡tower U lost.

sent more individuals than any other (save. micro- point to which all our arrangements converge is this,

SL'upical organisms), which for thousands of years —that a certain amount of force is involved in every

was the doiuiuaut typo of life on the globe, as shown orgnnixm, and that for every step in higher organi

by the remains imbedded in its rocks by myriads.'

Tho cuttle-fish is generally held to be the most

highly organized representative of this sub-kingdom,

and its appi arancc on the earth, or that of forms of

the same species strikingly similar, is much later

than that of the less highly organized individuals of

its division. More, according to the best authorities,

even the lower or less specialized members of the

family to which it belongs (the Cephalopoda) are also

prior to it in point of time, and these much resemble

the gronp (Gasteropoda) considered inferior to it in

point of organization. But although one Gastero

pod, or many, may have undergone modifications in

the course of time, which presented in the end more

resemblances to a higher species than to the one to

which it or they originally belonged, the theory of

progressive development by no means implies that

that course was necessary. And so, generally, we

may trace back the history of animal or vegetable

species on a thousand dilferent lines, but on each

the less and less developed organism manifests

greater reseinblanco to the immature forms of other

superior organisms, or to the permanent forms of

inferior ones. The educated Englishman of to-day

presents many distinctive points of characterdiffers mnch from the Frenchman, German, Italian,

Spaniard, &c. ; but step by step, as we go back, these

ditfereuecs become less and less apparent; and,

some two thousand years ago, who could have

defined their several ancestors among the barbarian inhabitants of the forests of central Europe?

How little did these again differ from the ancestors

of the Romans! Similarly, classes of Englishmen

at present vary greatly ; but the forefathers of some

of our proudest noblemen, at one time, were very

similar to ploughmen and mechanics—not to go

lower.
Moreover, our generalization does not imply that

Batrachiaus or lteptiles of some preceding epochs

were less highly organized than those which exist

in our own. Nay, rather ,the contrary; that such

have been as a class more highly developed than

any contemporary with man, as presenting under

more generalized forms certain affinities to higher
types. Such organisms had their special epochs in

ages anterior to that of intellectual man.
Further, though vast numbers of organisms once

coeval with molluscs on our globe, and possessing

a similar low type of structure, have yet in the

course of ages undergone extraordinary changes

—have progressed, as we say, to higher types,

—yet vast numbers of others rem: i in much the

same as they were thousands of years ago. Yea,

even such as they were in those primary strata,

wherein we find almost the beginnings of the world's

Ufe. And have we no "persistent types" of humanity? None in that Eastern portion of the

globe to which ull history anil tradition point as the cradle of the race?

Space prevents our considering further these analogies, as also some problems touched on in the articles on classification just referred to, but to the main difficulty which there presented itself we must devote a few lines, for it is the point we have had in view in writing these articles, in fact it is their rainoii d'etre! Having decided that vertubrate animals were from one point of view higher than invertebrate, yet we found that the bee belonging to the latter, on every principle on which humanity bases its judgment of superiority, was higher in the scale than some individuals belonging to the higher type. That, generally, structure could not he taken as a mark of superiority. That, in deciding the relative rank of different organisms, their properties, functions, Ac, had to bo taken into account, and that since these were different in different species, there was no common ground of comparison. Will not the study of humanity throw light on this question? Is tho Englishman, although later, more complex in his organization, superior in all respects to the Greek or Roman? All dovelop ment, we say, is analogous to human development, the eras of history to the phases of the growing mind, and these again to tho epochs of the growing world. That progression is from the simple to the more complex we allow ; hut is the more complex the more perfect 1 In the individual, is it the innocence of childhood, the enthusiasm of youth, the strength and intellect of manhood, or the judgment of age, which constitutes the more perfect phase? What is that " sense of something lost" which haunts the growing man, and which asserts itself in tho instincts of the race? Intellectually, humanity has advanced ; but does it not suffer some compensation for the advantages it has gained? Is intellect the sole criterion of perfection .' Language again is undoubtedly more complex now than in the time of Shakespeare, but can our abstract terms stimulate the imagination, rouse the passions, sway humanity like the simple ones? Is our more complex language then as perfect as when lees devolopoil? But that word ■' perfect" is vague and indefinite. Who has the true typ.; of perfect ? or who, having it, can demonstrate to his fellow-men that his is the absolutely right one? In our own opinion, the more complex is not the more perfect. But opinion is an unstable and variable thing ; the

COLOUR AND BRIGHTNESS OF THE
MOON'S SURFACE.

Тик following extracts from Mr. Birt's letter-
press to the fourth area of the Lunar Map ore
interesting in connection with an unstudied region
of the moon's disc which has every appearance of
being very ancient, and to have received its external
characteristics long anterior to Chacornac's epoch
of the production of the smaller and moro perfect
craters and blow-holes. It is also probable the
reader may discover indications of the basis of
a theory, which, if built up from telescopic obser-
vation aud the study of photograms, may intelli
gibly explain many of the difficulties which now
beset seleuographicol research.

"In numerous portions of the moon's surface, as
on that of the earth, we behold the results of the
operation of two opposing forces, one by which tho
features are moulded and, as it were, built up, im-
parting to the objects so produced on aspect of
freshness that it is impossible to question then-
comparative recent production: the other, by which
objects onco possessing all the characteristics of а
recent formation have yielded, it may have been
gradually, to surrounding influences, whatever they
may have been, so that at the present time they
exhibit the semblance of vast ruins, which in some
localities are unrelieved by even the slightest indi-
cation of the operation of a force of an opposite
character.

"Webb, in his very masterly paper on the moon,
in Froscr'a Magazine for September, ltílib,
p. 381, speaks of the possibility that the colossal
lunar formations may have been the resnlt of forces
acting in a more gradual manner, and with less
temporary vehemence than may seem to com-
port with the term explosion. It may be that
astronomers have paid much more attention to
those lunar features which are clearly the results
of explosive action, than to those which manifest
the presence of a degrading agency. It has been
considered that many of the larger forms have been
produced by rapid, violent, and tumultuary pro-
cesses; aud however true this view may be, it is
certainly inadequate to account for the present
appearinces of still larger tracts in which no ex-
plosive outburst of an epoch which may in any
sense be called recent occurs. Nearly filled as weil
as broken rings, interrupted mountain-chains, com
paratively smooth tracts without any well-defined
boundaries, are characteristic of such regions; and
it may be asked, in what manner and by what
agency have they attained their present condition?
Has the 'erosion' of Chacornac destroyed the
missing portions of tho broken rings? and has this
'erosion' acted suddenly or gradually f Has the
'diluvial,' restricted by Webb to the expression of
comparative fluidity, independent of the nature of
the material, invaded and nearly filled previously
deep craters so as to furnish a connected series of
well-known forms, from the smooth-floored walled
plain to the just perceptible ring above the surface?
Has this same 'diluvial' buried the lower portions
and the lateral spurs of continuous mountain-chains,
so that now the higher portions alone remain as
low, short, and detached ranges in the original line 1
One cannot help contrasting the continental region,
to use a terrestrial analogy in which this area IV An
occurs, with the magnificent chains of the Apennines
and Псетия, and the lower and smooth levels of
the Mare Imbrium and Mare Serenitatie, as exhi-
biting in a very marked degree the results of the
forces already mentioned. In the latter we see the
effects of comparative recent action in the produc-
tion of vast mountain-chains and the neighbouring
extensive level plains. In tho former these grand
features are wanting. The surface, although for
from being smooth, as that of the Maria, is
roughened only with the remains of former moun-
tains, rings, and craters; the degrading agency,
whatever it may 'have been, appears to have
operated almost unchecked in this region, and it is
a subject of interesting inquiry as to how this state
of things has been effected. Has the filling up, has
the wearing down (if such is the case) been gradual?
and what forces have been concerned in producing
the mutilated forms we now observe?

"Brightness and colour may ultimately become
keys by means of which a better acquaintance may
be obtained with the chronological sequence of
lunar formations. Chacornac refers the great
continental formations te on epoch anterior to that
of the production of the great plains, this, again,
being anterior to the period of explosive energy
contributing to the existence of numerous objects,
such as bowl-shaped craters and smaller blow-holes,
within the interiors of which no intrusive matter is
found. Reference, however, is not prominently
made to objects in mountainous regions similar to
those which we find in various portions of the great
plains—viz., partly buried craters and partially
destroyed rings, of which wo havo evidence in this

and adjoining areas to the west. The contrast of the general colour of the surface hereabout, as compared with that of the grey plains—its mottled and rugged aspect arising probably from its altered character from that which it possessed at a still earlier epoch—tho absence of that sharpness of outline in its remaining mountain-peaks or ranges so characteristic of those which we find nearer to and often on the grey plains, together testify to a much earlier epoch than oven that of the production of the partly filled rings on the grey plains. Bright white glistening surfaces, more or less in the neighbourhood of bowl-shaped craters and dark patches of a deep grey, approaching block, appear alike to indicate the most recent formations; the first, it may be, from loose fragmentary incoherent materials ejected from adjacent craters, the last from substances in a state at least of comparative fluidity which have escaped from the interior reservoir at the time of eruption. Phillips compares the bright glistening region of Aristarchus to one in which white trachyte abounds, and many of the basalts in terrestrial volcanic regions present a dark colour. Between the brightest and darkeet of such limited areas on tho moon's surface every gradation of intermediate tint occurs; and from a careful consideration of the phyeical aspects of those regions which, on tho one hand, reflect considerably less light than the brighter, and, on the other, considerably moro than the darker, it may be inferred that such regions ore amongst the most ancient of lunar formations."

Indications exist in the region to which the above extracts refer, that its earliett state, so far as our present selenographical knowledge will enable us to judge, was very similar to many of the more recent districts in which perfect craters and mountainous regions intermingle. This was succeeded by the formation of a neighbouring grey plain, accompanied by the invasion of the craters on its borders aud the breaking down of their walls facing the plain, remnants of which still exist. A further change posterior to the formation of tlie plain appears to havo been marked by the elevation of a chain of low mountains in the locality of the craters which liad been invaded.

Л NEW ANTISEPTIC.

THE hydrated chloride of aluminium, to which Mr. John Garagce has recently drawn the attention of medical men and of the general public, appears, says the Lancet, to be a valuable antieeptic. It is quite as potent as chloride of zinc or carbolic acid, and is at tho вате time uon-poisonons, and devoid of unpleasant smell of every kind. These qualities will no doubt ensure its being extensively used, and at no distant date we may expect it to displace the antiseptics which are at present in vogue.

It is somewhat strange that this substance should have been so long overlooked as a possible antiseptic, and Mr. Gamgee certoinlydeservee credit for suggesting the utilization of it for this purpose. The reason why it has been passed over is probably to be sought in its not being a waste product in any common chemical manufacture. The anhydrous chloride of aluminium, which is manufactured in order to serve for the preparation of metallic aluminium, is far too costly on account of the tronblesome nature of the process by which it is prepared —to wit, by passing chlorine at high tempcratnres over a mixture of aluminium and charcoal. By placing the anhydrous chloride of aluminium in water it is of course converted into hydrated chloride.

The most economical process for the preparation of the hydrated chloride of aluminium appears to be by double decomposition between sulphate of alumina and chloride of calcium (both of which are cheap commercial products). Whon solutions of these two salts are mixed together, sulphate of lime is formed and appears as a precipitate, whilst the hydrated chloride of aluminium remains dissolved.

On allowing the aqueous solution to evaporate at a very gentle heat and afterwards cooling, crystals of hydrated chloride are produced. H an attempt be made to drive off the water from the hydrated chloride by the application of heat, decomposition will take place. Hydrochloric acid is evolved under these conditions, and oxy-chloridc of aluminium is formed, and, by pushing the process, alumina is obtained as the ultimate fixed product.

Л NEW GUN.—According to the Scientific Journal, ot Philadelphia, there is incoarse of erection, on the esst sido оГ New York Bny, ft gun thftt will throw И00 five ounce balls in one minuto, to A distance of about t wo miles. The shot шлу be either red hot or colJ. The gun is circular, ftnil Rppeftrs liko two discs of heavy imn plate, about 4ft. in diameter; upon one side is a funnel to convey the balls through to the proper chamber, without cessation of firing or diminution of speed; the ntuzrJe projoets upon the periphery of the circular machine. пиЛ may be elevated or depressed at the will of the gunner by the trmmion upon which it rotates. The machine mftv be worked by manual labour nr steiim power, and when worked by the latter, it \t1u throw from five ounce balls to eight pound shot and shell, thus making It a destructive implement of warfare.

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