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bers of such systems would move ten times faster in perihelion than in aphelion, and for ten meteors along a given small range close by perihelion there would be 100 along an equal range close by aphelion. For 10,000,000 meteors then close by perihelion there would be 100,000,000 equally close by aphelion. But the latter set would be spread uniformly over the surface of a sphere having a diameter ten times greater than that of the sphere over which the latter set would be spread. The surface of the larger sphere would, therefore, be 100 times greater than that of the smaller sphere, while the number of meteors spread over it would be only ten times as great. It follows that meteors would be spread only oneten th as richly at the aphelion distance as at the per-ihelion.

On the average, the meteors belonging to such a system as the November one are spread eighteen times as richly (cubical space for cubical space) near the point of their closest approach to the sun as near the orbit of Uranus, beyond which their aphelion lies. Giving to the August meteors a period of about 100 years (the real period is certainly greater), we get a mean distance of somewhat less than twenty-two (the earth's as one), or an aphelion distance more than forty-three times exceeding the perihelion distance; so that the density with which these meteors are distributed in cubical space is, on the average, more than forty-three times greater at the point of nearest approach to the sun than at aphelion. And the like is true, mutatis mutandis, of every cecentric meteoric system, whether traversed by the earth or not.

To sum up then, we have—

1. Absolute certainty that the number of meteoric systems is enormous.

2. Very good reason for believing that meteoric systems aggregate as systems towards the sun's neighbourhood; and

3. Absolute certainty that individual meteors in every elliptic system are, on the average, much more thickly spread (cubical space for cubical space) near the perihelia than near the aphelia of their orbits.

The last relation, only true on the average as expressed for any given meteoric system, must be absolutely true when all the meteoric systems are considered together. For example, when the gem of the November meteor-ring-as Mrs. Wood finely called its richer portion-is travelling out in space beyond the orbit of Uranus, this system is, for the moment, richer out there than near perihelion, where the poorer part is passing. But we cannot doubt that this temporary effect is much more than counterbalanced by the superior aggregation of the numbers of countless other meteoric systems near the sun-we cannot, I mean, imagine that any one system, or even several systems, can even temporarily disturb the preponderance of aggregation in the sun's neighbourhood.

Is it conceivable that so tremendous an array of illuminated bodies, let them be as minute as we can suppose them to be, would give no appreciable light when the sun is totally eclipsed? Is it an idea so utterly wild and fanciful that the light actually seen during eclipses-where this long array of illuminated bodies has been shown to be-the sun's corona, I mean,-does actually come from them? Or, if we were disposed still to be doubtful as to this interpretation, ought not all doubt to be removed when such a practised observer as Captain Noble tells us he has actually seen Venus (when placed somewhat as shown in the figure at V) projected as a black body on a relatively light background? When some one shall have shown me whence the light illuminating that background can have come, except from beyond Venus, or how, supposing it so to come, any doubt can exist that during total eclipse we ought to see some such light, I shall prepare to admit that there is no objection to Mr. Lockyer's theory that the corona is a phenomena of our own atmosphere, except that it does not square with Mr. Freoior's opinions."

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But there are other consequences to be considered. I reserve them for a future paper, in which I shall, in the first place, show how the results here deduced serve to explain the zodiacal light in a very satisfactory manner-even the phenomena hitherto considered most perplexing; how the zodiacal light is brought into direct association with the corona; and, further, how the peculiarities of comets, as distinguished from meteoric systems, find their counterpart in the peculiarities of the corona and zodiacal light. I would specially invite any readers of the ENGLISH MECHANIC who find my reasoning either obscure or unsound in any place, to kindly point out their difficulties or objections. I have no wish to make out a case, but to interpret, if I can, the phenomena I have referred to. Let me add that I can see no reason for waiting because we hope to gain new information during the eclipse of next December. The more earnestly we try to educe the meaning of what we have already learned, the more significant will new observations become. There is a

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good deal of affectation (to say nothing of downright laziness) in the continually repeated advice to wait for fresh observations. The warning addressed specially to me reminds me of Miss Lavinia Spenlow's remarks about "mature affection." Mature science," Professor Pritchard seems to say, "does not easily express itself. Its voice is low. It is modest and retiring; it lies in ambush, waits and waits. Such is the mature fruit. Sometimes a life glides away and finds it still ripening in the shade." I confess I prefer a fruit of somewhat quicker growth.

(To be continued.)

ANTIQUITY.

BY ARTHUR UNDERHILL. (Continued from page 411.)

CHAPTER V.

and I shall therefore proceed to the consideration of it first, and shall then take the others in order. In a previous chapter, I said that, after the first convulsion had taken place, the sea deposited a system composed of the detached particles of granite. This deposition formed the gneiss system, and so well was the character of the original granite preserved that it is in many cases extremely difficult to tell the difference between the granite and gneiss rocks. The stratification of gneiss, however, is a sure test, and in most cases it is marked enough, although in others, on account of the very contorted and flexured stratification of the primary rocks, it is a work of difficulty to follow it. Gneiss is, however, of a neater appearance than granite, if I may be allowed to use such an expression.

The contorted appearance of the metamorphic strata is (when the flexures are large) generally accounted for by the supposition of an immense lateral and vertical pressure acting upon them while yet in a soft and yielding condition; and when the contortions are small, they are explained by the help of an analogous case, which presents itself to our notice at the present daynamely, the phenomenon of ripple marks, which is seen on the sandy beach of any of our many watering-places. The sea at the time of the. deposit of the gneiss was in an excessively troubled condition, and in consequence the motion of the waves was communicated to the very bottom, instead of being confined, as now, to the shallow portions of the ocean. The first cause of contortion, namely, lateral and vertical pressure, has been experimentally demonStrated by Sir C. Lyell. He took some clay, and having made of it several slabs or cakes, he placed them one upon another on a table; he then placed two pieces of board, one at each end, and upon the top he laid another board very heavily weighted. He then, by means of a press, forcibly contracted the space between the side boards. The result was that the slabs were bent and contorted in a similar way to the strata of the primary rocks.

The strata of the gneiss system are gneiss proper, composed of quartz, felspar, and mica ; syenitic and porphyritic gneiss, of the same minerals as syenite and porphyry respectively; and quartz rock.

the mica schist. This has by many geologists The next system in order of superposition is been classed with the gneiss, both on account of the similarity of the characteristics of both systems, and also because their order of superposition, unlike any other groups, is somewhat uncertain. However, as for purposes of description it is more convenient to keep them apart, I have adopted that method. Mica schist differs from gneiss in the entire absence of felspar, and has, therefore, an appearance of a white glistening stone, which is for the most part laminated like slate. It is, as a rule, softer than gneiss, more AND distinct in its lines of stratification, and less crystalline. Its chief strata are mica schist proper, composed of mica and quartz; tale schist, in which tale supplants the mica; chlorite schist, where chlorite takes the place of the mica and gives a greenish colour to the stone; hornblend and actynolite schist, of hornblend and actynolite respectively with quartz; and primary limestone, such as the highly crystalline Carrara, and other pure marbles. The meaning of the word schist is somewhat similar to that of slate, and is used to signify that such rocks are laminated. The gneiss and mica schist systems are very plentifully distributed over Scotland, but are extremely rare in England. I may mention, as examples, the passes of Glencoe and Killiecrankie, and the mountains around Loch Katrine.

AVING investigated the nature of the ig

Now, even giving up the second of the above THE WORLD: ITS FORMATION conclusions as not absolutely demonstrated, the other two remain, and leave us no manner of doubt whatever that the neighbourhood of the sun must be more abundantly crowded with meteors than the track through which the earth pursues her course. But it has been proved that within every space along that track equal in size to the earth there must, on the average, be some 13,000 large meteors, and forty times as many small ones. If the whole space enclosed by the earth's orbit (to consider no farther) is at least as richly supplied with meteors as this (and I see no escape from the conclusion), some rather remarkable results follow, which we shall do well to consider somewhat attentively.

"V

N

Here is one-Let Ee be a cylinder enclosing the earth at E, passing pretty close by the sun S at N, and extending to the earth's orbit again at

e.

H neous rocks, we now come to the con

sideration of those of an aqueous formation. The oldest, and in consequence the lowest, deposit of this species is that which is called the metamorphic (from two Greek words, signifying changed in form) or primary class. The rocks of this series are termed metamorphic because they appear to have undergone considerable alterations since their deposition, and under the influence of pressure, heat, and chemical forces, to have assumed a semi-crystalline character, which is not possessed by the ordinary aqueous strata. They are also called non-fossiliferous, hypozoic, under life), or azoic (without life), because they contain no remains of plants or animals.

The primary, metamorphic, non-fossiliferous, hypozoic, or azoic class (for by all these names is it known) comprises three systems or groupsnamely the GNEISS, the MICA SCHIST, and the CLAY SLATE systems.

The length of this cylinder would be about 180,000,000 miles, a length containing the earth's diameter some 22,800 times, and therefore the volume of the cylinder would exceed the earth's more than 34,000 times. The cylinder would therefore contain more than 442,000,000 meteors such as become visible to the naked eye when traversing It will, perhaps, be noticed that in the list of our atmosphere, and 17,680,000,000 smaller ones, rocks in order of superposition I have placed the or more than 18,000,000,000 meteors of one sort clay state system in the class of secondary or another. These would be illuminated by the rocks. This was, however, a lapsus calami, which sun with more or less brightness-those near NI must beg my readers to excuse. It should have with an inconceivable glory of light (these, too, would be so heated as to be incandescent, if not vapourised), and they would turn more or less of their illuminated portions towards the earth.

stood at the head of the primary class, and the Cambrian system should have been inserted in its place at the bottom of the secondary class. The gneiss is the oldest and lowest of the three,

We now come to the clay slate group, specimens of which are so continually seen in the roofing of our houses. It is of various colours, from light grey to black, and its texture is also subject to considerable modification; it is, however, much finer than that of gneiss or mica schist, and the minerals of which it is composed appear to be the finer and more impalpable particles of water than matter. The lamination of this group is particularly marked, and renders it of the greatest use in the arts, as it splits up into plates of the most perfect thickness throughout. The cause of this property is very obscurely understood, but is thought to proceed from chemical and magnetic action combined with heat, acting whilst the strata were under great pressure. The line of lamination, or cleavage, is not generally the same as that of the strata, but lies at all angles to it.

The scenery of the clay slate system is very wild and abrupt, the strata being tilted up into

the most fantastic shapes and forming precipices of tremendous depth.

I have now reviewed the primary rocks, and in my next chapter shall commence the consideration of the secondary class, which is of far greater extent and of much more interest than the metamorphic or non-fossiliferous systems.

(To be continued.)

MICROSCOPICAL JOTTINGS IN TOWN
AND COUNTRY.
No. IV.

TH

HE name of micro-fungi is legion, there are at least 2,000 species for the study of which the microscope is essential, and, as I have before said, any person having good eyes and a fair amount of patience may collect a goodly number with little difficulty, from the beautiful "cluster cup" (Ecidium) to the humble smut (Ustilago). He will find ample scope for real earnest work

which is not without its reward.

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Whilst upon the subject of fungi, I may touch upon the yeast fungus, concerning which enquiries have lately been made by correspondents in the ENGLISH MECHANIC. In John Quekett's Lectures on Histology," and in Dr. Carpenter's Microscope and its Revelations," drawings are given of the various stages of the development of this plant, accompanied by a lucid description, which we cannot do better than abridge. The initiatory stage is that of a simple cell, which we may regard as the perfect plant. Place one of these in a saccharine fluid containing also albuminous matter, and each cell "rapidly puts out one or more projections which appear to be buds," that speedily become new and complete cells, themselves to increase in like manner, so that in a few hours a single cell will develop into several rows of cells, all remaining in continuity with the parent cell, but existing independently, and exercising all the functions of separate plants. If we check the process of fermentation these separate into single cells, and return to the isolated state we call yeast. Any of our readers can easily examine these for themselves if they be provided with a good in. or in. objective, and, by a little ingenuity, can devise means by which the process of development may be watched for a considerable period.

Various "insect preparations are generally to be found in our microscopical cabinets, and usually attract a considerable amount of attention from the outside public, so that I am not surprised that "C. R. H." (15. 4328), requests me to give some information as to the best means of "putting them up." It will perhaps be more interesting to the readers of the ENGLISH MECHANIC generally if I give a few hints as I touch upon different kinds of insect preparations than if I give "C. R. H." a formal reply. Premising that he will require a few glass slips 3in. x lin., a few thin covers, either square or round, about in. across, a little balsam and gold size or asphalte varnish, I will for the present dismiss the subject. But if our readers wish a short paper on mounting I will try and meet their wishes as best I can.

The House Fly.-The proboscis is the favourite portion of this insect, and is really, when nicely prepared, a splendid object in the hands of a good manipulator, and furthermore affords a good test of the correctness of the lens used. We have to remove it from the head of the insect, soak it awhile in pure turpentine and mount it in balsam, paying great attention to its arrangement on the slide.

Balsam, when used in mounting, should be of medium thickness, and it is usually desirable to warm both slide and cover slightly, in order that the balsam may flow freely, and air bubbles be less likely to be included. When mounted, the slide must be placed awhile in a warm room, until the balsam becomes hardened, when the slide may be cleaned off. Under a good lin. objective we can make out the anatomy of the proboscis very well. Briefly we may describe it as consisting of the two lobes of the lingula, or the expanded portion which is pressed upon our hands when the creature "bites" us, of the lancets formed by metamorphosis of the lesser pair of jaws (called the maxille), and of the maxillary palpi, small appendages attached to the latter. Certain ring-like markings on the lobes of the lingulæ are really metamorphoses trachea, as may be made out by a good lens and careful focussing. I have often watched, with much interest, through an ordmary inch pocket lens, the creature at work apon a lump of sugar, and have seen it pump up

the dissolved sugar as though it were determined first noticed this narrow mountain chain perfo-
to lay in as much as possible in the least possible rated in parts by craterlets, and which he calls a
time.
crater-rill, on February 3rd, 1865, although the
The eye of the fly is perhaps not so easily pre-eastern part of the same mountain wall he had
pared. We must carefully remove it by cutting known as early as August 17th, 1843.
round it with a fine pair of scissors, lay it on a
slip of glass and wash it freely with clean water.
A few minutes' soaking in potass solution will im-
prove it, but I have rarely found this to be neces-
sary. So soon as we have made the eye perfectly
clean by washing away all its pigment, we may
remove it to a clean slide and lay a piece of thin
glass over it, add a little pressure to ensure its
flatness (it is often needful to notch the eye all
round), and allow it to dry at its leisure. When
quite dry, we may moisten it in balsam. Under
a good in. or in. we find that the eye is com-
posed of a great number of hexagonal facets, of
which there are as many as 4,000 in the two eyes.
Each facet is the "corneule" of a distinct
'ocellus," and may be correctly regarded as a
perfect eye. The question has often been asked
whether a fly with its 4,000 eyes sees but one object
or many at once. To this there can, I think,
be but one answer-viz., that it receives but one
image at once, and that one impression only is
transmitted to its brain. The why and wherefore
of this, our readers may profitably work out by
the aid of their microscopes. To explain it here
would require diagrams and more space than

66

can ask.

I

I must reserve further notes on the fly until
my next, which I think ought now to be my last,
as it is unfair for one contributor to monopolise
space for too long a time together.
H. P., Hull.

IT

The observer will not be long in ascertaining, under the oblique illumination at the time of first quarter, or a little later, that the mountain wall separating Albategnius from Hipparchus is but a small portion of a line of cliffs extending eastward to the junction of the borders of Ptolemæu and Alphonsus, a very rugged and rocky region, and westward as far as the two craters on Webb's map 64 (Ritter), and 65 (Sabine). The faces of these cliffs are very steep towards Hipparchus, the depressed level of which appears to have resulted from subsidence. At the time of full moon, a ray from Tycho, the metropolitan crater of the moon, as it is called by Webb, crosses Hipparchus. This ray, by comparing lunar photograms taken at the full, and shortly after the first quarter, is found to traverse very uneven ground, which is sufficiently connected and linear in its direction to warrant the supposition that it has been dislocated and shattered in the line of the ray, and therefore that the ray and fault are mutually connected. At the point where this fault or ray crosses the mountain wall common to Albategnius and Hipparchus, the wall has been greatly disturbed, and from the manner in which this has been effected it is probable that the ray from Tycho is the most recent of the two.

In Webb's map there are four small craters, three on the S.W. border of Hipparchus, and one within its enclosure north of them. The largest has been called Halley, and the one west of it Hind, the northern one within the enclosure of Hipparchus has been termed Horror. The obTELESCOPIC WORK FOR MOONLIGHT server will find a small crater west of the three,

EVENINGS.

BY W. R. BIRT, F.R.A.S.

There are similar peaks on many parts of the moon's surface well deserving attention. Of these mention may be made of Pico (Webb, 131) on the south border of the ancient plain called Newton by Schröter. The plain is visible for a short time only, but Pico, with an altitude of nearly 8,000ft., may always be seen. There is also a tine peak on the east border of Plato (Webb, 132) named by the late Dr. Lee Rupes Smythii," which Schmidt finds to be 9,000ft. high. Peaks of this kind should be well examined under every phase of illumination.

66

on the S.W. border, forming a conspicuous row of four craters, which is well worth his study. From the three craterlets on the mountain wall between T is well known that the finest views of lunar Albategnius and Hipparchus, the cliffs pass close scenery are obtained about the times of the to the N.E. border of Halley. An interesting first and last quarters of the moon, when the feature connected with Halley is a peak common boundary of light and darkness, which is to its border and the cliff, which according to technically called the terminator, divides the Beer and Mädler rises to the height of 3,543 visible disc into two portions; in the first English feet. The western foot of this peak is case, before the full, the western or day perceptible within the interior of Halley, and it side, and the eastern or night side, which in sends out a spur towards the N.E. on to the floor the second case, after the full, are reversed. With of Hipparchus, which has a rapid declivity. As such telescopes as those mentioned by Webb in the sun rises upon the spur it appears as a fine his interesting work, "Celestial Objects for Com-line of light, and is a very interesting object, mon Telescopes," the irregular and rugged line separating the two is well brought out. On the west of the first lunar meridian (the line on Webb's map joining the letters S and N) may be detected, about the time of first quarter, the formations numbered on the map 288 (Hipparchus), 289 (Albategnius), and 290 (Parrot), and as the terminator moves eastward one of the finest chains of walled plains to be found on the moon, just eastward of the first meridian, comes into view-viz., 208 (Ptolemæus), 207 (Alphonsus), 204 (Arzachel), 202 (Purbach), 201 (Regiomontanus), and 200 (Walter.) These formations are mentioned as being calculated, when beheld through a good glass, to arrest the attention of the observer by the magnificence of their appearance and the quantity of interesting detail to be found in their immediate neighbourhoods; it is, however, to a few of the characteristic features of Hipparchus that attention is solicited, as this formation exhibits in many respects, a marked difference from its neighbour Ptolemæus. Although the boundaries of each may be easily recognized when the sun has newly risen upon them, those of Hipparchus differ so greatly from the usual boundaries of walled plains, which are more or less visible under every angle of illumination, as to remove Hipparchus from this class of lunar objects, its general outline being lost to view in about forty-eight hours after sunrise upon it, it is rather, as Beer and Mädler describe it, "an assemblage of diverse lunar forms than a general whole." Under suitable illuminations these diverse forms possess considerable interest for the explorer of the moon's surface.

If the observer be fortunate enough to catch the terminator on the eastern part of Hipparchus, there is little doubt of his being greatly interested in contemplating the high chain of mountains which separates Albategnius from Hipparchus. The summit of this chain, which is narrow, appears at the time of sunrise upon it as a brilliant line of light, and he will soon detect upon its western portion three craterlets-the northern half of the middle one having been elevated apparently by the upheaval of the narrow strip of mountain, while the southern half has remained at a lower level. Schmidt

Mention of a feature connected with the mour tain wall to which the attention of the observer was first directed must not be omitted; it is that the western of the three craterlets is the brightest, and immediately below it, on the face of the el is a shallow ravine, which appears on Rutherford's photogram, 1865, March 6th, as if it had ca excavated by the flowing or descent of material over it, and on the floor at the bottom of this ravine is a mound of spparently accumulated material. It is very desirable that further observations of crateriet, ravine, and mound, should be made, also that the rocky region in the intermediate neighborhood should be well examined, for it is in such localities that discoveries are likely to be made. Schmidt says:-" As other objects of a rigorous and searching examination, I mention those little craters, crater rows, crater rills, that, situated in the interior of the ring mountains, form the limits of the plain and the beginning of the wad mountain. Here the eruptive forms have issued, as it were, out of cracks, and in parts of considerable and high mountains, where two mountain masses approaching each other form a narrow valley, or a sharp corner."-Report of the British Association for the Advancement of Science, 1865, p. 307. Craters are much more numerous on the rocky land filling the region between Albategnius and Ptolemeus than they are to the westward, but as yet no evidence of recent formations has been met with.

It is probable that on some future occasion the interesting features on the floor of Hipparchus may be described.

CHAPTERS ON CURIOUS CATERPILLARS. claspers brown. This is by no means an easy caterpillar to rear in confinement; though it may

A

we

AUGUST.

By J. R. S. CLIFFORD.

secondly, with markings in the shape of the letter V, and these are of a dull violet hue. The quan tity of leaves consumed by these caterpillars when in their last stage is extraordinary, and having arrived at maturity they enter the earth to a considerable depth and there construct a cell composed of a gummy substance mingled with earth. Not unfrequently, when potato-fields are dug over, the caterpillars and chrysalides are turned up, the former being called "locusts" in the midland and northern counties. The chrysalides thus got are sent sometimes to London or to other towns for sale, and some years they may be purchased at a moderate rate by those who may be curious to see this magnificent moth emerge. The getting the moth out is no easy matter, for very often the chrysalis has received some unnoticed injury when unearthed, and afterwards the temperature and the moisture or dryness of its condition must be nicely adjusted in order to secure its emergence.

seven

Considerably less in size, though still to be reckoned a large caterpillar, is that producing the Privet Hawk-moth (Sphinx ligustri); this is so conspicuous on the privet hedges that those not insect-hunters sometimes see it, and pause to admire its beauty, as I have myself noticed in the be found sometimes in good condition, on a trunk vicinity of London. This has also a horn, pointor paling, making its way to the earth, where it ing backwards, black and shining above, and usually spins its cocoon in some dry nook, not yellowish beneath. The ground colour is a appearing as a moth till the spring, which is the delicate green, and along the sides are case with others of the genus. Another hand- stripes, which are purple and white. A few some caterpillar, not very frequent, is the Coronet days before the caterpillar is adult, the colour of (A. ligustri). This refuses to roll itself up when the stripes fades, and the green of the rest of the alarmed, but moves off with some speed. The body turns to a brown. Entering the earth, the head is of a very light green tint, and appears caterpillar finally scoops out a cell, in which it almost transparent; the general colour of the body becomes a chrysalis, on the front of which there is also green, while down the middle of the back is a sort of beak, which contains the proboscis of is a narrow white stripe, and below this another the future moth, whose appearance on the wing broader stripe of yellowish-white, which does not is usually in June. Feeding on the lime or the kowever reach to the spiracles; on each segment elm, and in some places not rare, we may disthere are a few silky bristles. Though called cover during August the caterpillar of the Line It is rather after the privet in its Latin designation the Hawk-moth (Smerinthus Tilia). caterpillar before us seems to prefer to feed on partial to the higher branches of trees, whence a the ash, near the roots of which the chrysalis may brisk wind occasionally dislodges it, and sends it be found in some slit in the bark or hidden in to the ground, not advantaged by the fall. But, moss. The cocoon turns black after a certain like others of the family to which it belongs, it time, and is somewhat of a gummy texture. On grasps the branch or twig on which it rests with the alder there is sometimes detected, though great tenacity, and may be injured if torn very rarely, the caterpillar of the Alder Dagger suddenly from its hold. This caterpillar is (4. Alni), and this is remarkable not only from its shagreened all over, and sprinkled with yellow scarceness, but because it curiously differs from dots, the ground colour being green; on the sides the other caterpillars of the genus. The head is are disposed the seven stripes so frequent amongst very glossy, and as broad as the segment to the Hawk-moth caterpillars. The anal horn is which it is united, black in colour. The body is blue on the upper surface and yellow underneath, purplish-black, and along the back are situated a while close to it there is a very singular plate or series of yellowish-white markings, which are circlet, purple, edged with yellow. This is not sometimes absent, wholly or partially. The most found in the two other caterpillars belonging to singular circumstance connected with its appear- the same genus (Smerinthus), and which are ance is that on each segment there is what has commonly known as the Eyed Hawk-moth, and been called a process or "appendage," black the Poplar Hawk-moth, though in other points and flattened, and unlike anything seen in other they are not dissimilar. The caterpillar of the British caterpillars. In confinement this cater-Eyed Hawk is most partial to willow, occasionally pillar has been found to eat other leaves besides visiting fruit trees, and in this the horn at the those of the alder. The cocoon is compact, and tail is blue, which at once distinguishes it. That usually concealed. of the Poplar Hawk is generally more of a yellowish cast, and along the sides close to the spiraclesthere runs a series of red spots.

UGUST is very often a month of sunshine, and one also favoured with heavy showers of rain. The first is agreeable enough to many of the caterpillars now feeding, though there are some so squeamish as to resort to various concealments during the heat of the day, preferring to feed while the early dew studs the leaves, or at night, when they can come abroad with the additional advantage of not being in danger of their lives from some vigilant bird intent on filling its own crop, or intently engaged on the more benevolent business of providing for the wants of a helpless brood. There are some caterpillars, too, which seem indifferent to the rainfall-in fact, perhaps rather enjoy a shower bath than otherwise; while again, in many species, the dislike and avoidance of moisture is notable. After a summer's rain, shall find numerous caterpillars, especially young and naked ones (for the hairy and spiny individuals have the best of it at those times), sadly bedrabbled, or even lying half dead, while a certain portion are actually killed; and there is no doubt the numbers of some destructive species are thus diminished by drenching showers or long rains, to the advantage of vegetation. What are commonly called by collectors the Dagger moths (from peculiar markings found belonging to the very deficient family of the Bombyces. Some of them are amongst the earliest on the wings of some species) belonging to the genus Acronycta, and the family of the Noctua, in the caterpillar state remind one rather of those captures made by the young seeker of caterpillars, who is surprised at the emergence of a moth or moths not at all resembling his expectations. The most common of all is the Grey Dagger (A. Psi), which occurs all over the country, and even in the heart of towns. On the back of this caterpillar are two humps-the first being long and horn-like, on the fifth segment, and at the extremity of the body is another, shorter and broader; the former of these is deep-black, covered with hairs; a yellow stripe runs down the middle of the back from the third segment, ending at the anal lump, and on each side of this is a black stripe of the same breadth; enclosed in this stripe on every segment from the fifth there are two red spots and two white warts; beneath this black stripe again there is a grey one on each side, tinged with red, and hairy. The head is black and shiny, like that of the well-known Tiger caterpillars, often called "Woolly Bears." The caterpillar of this species is by no means particular as to its food, roving about in gardens from plant to plant, and from tree to tree, sometimes continuing to feed until late in autumn. Closely allied to the preceding is the so-called Dark Dagger (4. tridens), though not noticeably darker; indeed, in the perfect state the two species are so alike that our greatest entomologists find it no easy task to distinguish them. The caterpillars, however, are markedly distinct, and of the two, Our largest native caterpillar is to be found of tridens is apparently the scarcer species, though its full dimensions at the end of July or during widely dispersed. The body of the caterpillar is August, and he who has once seen it will not black, having numerous orange and white spots easily forget its appearance and proportions. disposed in a regular manner;there is a narrowish Though most partial to the potato, it has someorange-yellow stripe along the back from the sixth times been detected on the privet, the jessamine, to the eleventh segment. There is a hump, as in and several other plants. Whatever its food it tridens on the fifth segment, black on the top usually hides from view during the day, going but grey behind; and on the twelfth segment there to the surface of the earth, or to the thicker poris a slight hump, with a snow-white mark on its tions of some bush or shrub. When at its greatest top; behind this is a horn pointing backwards. size, the caterpillar of the Death's Head is nearly There is a stripe along the sides containing the five inches in length. It has long been noticed spiracles which is mottled with yellow, not that the moth had the power of producing a grey, as in the preceding. This caterpillar is peculiar sound, so stridulous as to be sometimes most partial to the blackthorn and whitethorn, called a squeak, and some of those who have and remains out, like its relative, for some time; reared the caterpillar assert that it has also a the cocoon is generally spun in a crevice of the rather similar faculty, only the noise resembles bark of some tree. The sycamore is not a tree more the snapping of electric sparks. Others favoured with many insect dwellers, but one of the have failed to perceive this, and have questioned devourers of its leaves is the caterpillar of the the truth of the statement. This caterpillar, like Sycamore Dagger (4. aceris), which generally so many others of the Sphinx family, has an anal prefers to feed on the higher branches, also eating horn, which is rather rough, and has a double occasionally the leaves of the horse chestnut. bend downwards at its junction with the body When alarmed it assumes one of the positions and then upwards again close to the tip; in colour shown in the figure, and remains unmoved for a good while. The body is of a dull flesh colour, but this is scarcely noticed, owing to the long hairs which clothe it, and which, though varying in tint, are usually yellowish-red; some of these hairs form a series of "facicles," or brushes, each series having nine. Along the back we find a series of white spots bordered with deep black. The head is black with a white mark like the letter V, the spiracles and legs are black and the

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66

it is yellow and black. The head, which is occa-
sionally almost withdrawn beneath the second
segment, is orange-yellow, with a brown stripe on
each cheek, commencing at the crown and running
down to the mouth; the colour of the body is
rather lighter, and the yellow passes into green
on the under side; on the three segments imme-
diately behind the head there are no spots; but
the other segments are highly ornamented-first,
with a number of oval deep purple spots, and

Some curious caterpillars of butterflies are feeding in the month of August, and several belonging to the Vanessa genus are full grown at this time, or a little earlier. It is singular that several of these live exclusively on that apparently unpalatable and most abundant plant, the stinging nettle. Living in companionship almost throughout their caterpillar life (which only lasts from four to six weeks) we have the small tortoiseshell (V. Urtica), a beautiful insect as it sports from flower to flower. The caterpillars of this species vary much in colour, being all shades of grey, mingled with yellow, green, or black. The head is shiny and black, while the claspers are quite pale. The whole body is covered with what are called compound spines. That of the peacock (V. Io) is also social until the last change of skin. Here the ground colour is a rich black, not variable, and freckled all over with white dots, which seem to be arranged in rows. The spines are long and compound. Rather hermit-like in its habits is the caterpillar of the brilliant and fearless Red Admiral (V. Atalanta), and not only does it choose to live alone, but draws the leaves slightly together with silken threads as an additional security. This is very dark grey, or sometimes reddish-black, slightly marked on some parts of the body with white, and with a wavy yellow line along each side. The spines are of a reddish-brown. Sometimes on the nettle, but more frequently on the thistle or the burdock, protected by a slight

silken web, dwells the Painted Lady caterpillar (V. Cardui), similar to the preceding, but darker, and having usually more stripes. Singular as this caterpillar is, like many others, it gives no indication of the splendidly adorned winged insect it is to produce. In some years the Painted Lady is scarce, and the cause is doubtless a mortality amongst the caterpillars, as they appear to be liable to severe attacks from insect enemies. The

REVIEWS.

Contributions to the Mineralogy of Victoria. By
GEORGE H. F. ULRICH, F.G.S. Melbourne:
John Ferres. 1870.

Tminerals hitherto found in the "richest gold-
HIS little pamphlet contains a list of the

The Quarterly Journal of Education. London:
T. J. Allman. July, 1870.
THE latest number of this unpretending quarterly
is now before us, and we are astonished at the
amount of interesting matter it contains. That a
journal devoted to the interests of schoolmasters
this magazine is really more than could be ex-
should be well written cannot occasion surprise;
but that it should contain such papers as are printed

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bearing country in the world." Victoria possesses caterpillar of the large tortoiseshell is little not only the very essence of mineral riches, but it pected. Thus we have an article on is likewise the home of several minerals which are new to science; but taking into consideration the small number of different mineral species hitherto discovered in the many hundred of auriferous lodes opened up throughout the country, and comparing the result with the dozens of fine minerals occurring in the ore-lodes of Cornwall, Saxony, the Hartz, &c., the reward for mineralogical research appears rather a meagre one.

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known in this country. Unlike its brethren, it rejects low plants, and climbs tall trees, especially the elm and the sallow. This is also spiny, and of a dull yellow hue, with a black stripe on each Some of the Geometric caterpillars to be seen this month are large and singular. That of the Peppered Moth (Amphydasis betularia), when reposing, stretches out its head in a peculiar manner, having almost invariably a silken thread passing from the month to some part of the branch, and thus securing it against a sudden shock. This caterpillar has the head notched on the crown. The ground colour varies much, even in individuals from the same batch of eggs, some heing clay-coloured, others greenish or brownish. There are two conspicuous red spots on the back of the ninth and twelfth segments, and six similar and one in particular, presented to the National no doubt that Dotheboys Hall has been greatly

One letter in

Political Economy as a Means of Education," by Professor Rogers; a paper by A. R. Hope, the well-known author of the Book about Boys," "Stories of School Life," &c.; and a short description of the R. Morell, LL.D. There are also some useful State of Linguistic Studies in France," by J. all students of the language and afford some mental notes on ** The Twelfth Night," which will interest pabulum to lovers of Shakspeare. able cassiterite, and magnetite; and among be expected, replete with matter for thought, The list includes bismuth, stibnite, the valu- other interesting subjects are discussed, and the columns devoted to correspondence are, as might precious stones the sapphire and oriental ruby, although naturally enough connected principally topaz, garnet, and opals; while Selwynite, pyro- with schools and schoolmasters. minerals known to science. phyllite, and taleosite are among the more recent Speaking of the particular we would commend to the attention of rubies hitherto discovered, the author says that those of our readers who have any notion of sendseveral have been found of a size worth cutting, ing their children to boarding school. There is from its fine violet colour, be called by jewellers the is still ample room for improvement. At the Museum, a small, but nearly perfect crystal, would, changed for the better, but the facts related in this communication show very clearly that there oriental amethyst. It resembles the quartz amethyst, but its distinction from the latter is present time, while the education question is so rather handsome and stick-like caterpillar, having perior hardness (scratching topaz), and its action Education to interest everybody, and we coreasily proved by its more acute pyramid, far su- fiercely debated, there is matter in this Journal of upon the dichroscope. It shows before the blow-dially commend to our readers a periodical so ably generally recorded for the spinel ruby, but which pipe, on and after strong heating, a behaviour is also characteristic of the oriental ruby; it turns quite a dark opaque, but on cooling becomes green, then colourless, and finally resumes its original red colour.

ones along each side.

trees; in the birch, whence it has its name, it is The food is a variety of rarely found. The chrysalis is buried beneath the earth through the winter. The Great Oak Beauty (Boarmia roboraria) is developed from a

two humps on the sixth segment. The colour is a chequered tinge of black and white, and down the middle of the back there is a slender thread. Oak is the chief food of this choice caterpillar, which has been taken formerly in Richmond Park, and still occurs in the New Forest, and a few other places in the south of England.

PLATINISED MIRRORS.

At

conducted.

ON ZYMOTICS."
(Concluded from page 415.)
OTH the specific process

This book will doubtless be of use to crystallo-B have a tendency to terminate in the restore.

graphers, as correct figures of the more interest-
ing crystals are given, together with accurate
measurements of angles for the determination of the
indices of the planes of some of the new crystals.
As a record of the more recent discoveries of the
minerals hidden in one of our most distant
colonies, this little brochure must be of interest, if
not of value.

tion of the sufferer to health, without any intervention of the medical art. But at the termination of these conditions a state of health, often wretchedly below par, is left behind. Scarlet fever frequently destroys the drum of the ear, by extension of the sore throat backwards into the Eustachian tube, and there sets up an ulceration by which the patient's life is in constant jeopardy: at any time, too, from the fading of the rash until a month afterwards, that fatal form of dropsy, called scarPewtner's Comprehensive Specifier. A Guide to latinal dropsy, may supervene on the slightest exposure to cold. Measles, chicken pox, and the Practical Specification of every kind of whooping-cough, very slight in themselves, leave Building-Artificers' Work. Edited by WILLIAM behind a predisposition to a most fatal complaint, YOUNG, Architect. London: Longmans. After the deposit of tubercles in every part of the body. THIS handy work of reference will doubtless save In grown-up people the brunt of the disease usually the architect and builder some trouble and time, falls upon the lungs, and it is then called consump to form a specification, which are printed in dis- generally throughout the system, the brain and containing, as it does, the various items necessary tion; but in children the disease is spread more tinct paragraphs, and marked by consecutive other organs suffering quite as much as the lungs. This disposition to tubercle arises after these three numbers for facility of reference. diseases without any previous hereditary taint or also an appendix, which contains a specification inclination whatever. The zymotic diseases, then, form of building conditions and agreements. think them to be, but even the mildest may leave befor repairs and alterations, together with a short are not the harmless ailments which the public Those of our readers who are aware of the dis-hind the seeds of a malady which, sooner or later, putes which often arise between architect and will destroy life. builder, or between the former and his employer, through some item of a specification being insufficiently or wrongly described, will readily un

HE cost of large mirrors, to whatever cause it may be due, is undoubtedly larger than what the nature and price of the materials of which they are composed would lead one to imagine. We are not now alluding to a framed mirror, but simply to a given area of glass and quicksilver. It has therefore been proposed, some years since, to dispense with the silvering and substitute a preparation of platinum. Aisne, this system, which was introduced by M. Dodé, is in full operation, the basis of the process being the chloride of platinum. being thoroughly well cleaned, the glass receives the liquid, it is then moved about in various directions, so as to ensure the layer or film being uniformly spread over its surface. The liquid has a slightly oily character, as it is mixed with a quantity of essence of lavender. It spreads gradually, and dries without leaving behind the faintest tint of any kind. The platiniferous compound is made as follows. About three and a half ounces, avoirdupois measure, of thin platinum ribbon are dissolved in aqua regia, dried in a sandbath, care being taken to avoid the decomposition of the newly-dried chloride of the metal; spread

There is

The circumstances under which zymotic diseases are enabled to spread are the following. First of all, the zymotic principle itself must be present;

out upon a glass surface, and the rectified essence derstand and fully appreciate the value of such next, a condition of the atmosphere or of the sur

of lavender added, little by little. So soon as nearly fifty ounces of the essence has been poured upon the chloride, the mixture is placed in a porcelain vessel, and left completely undisturbed for eight days. At the expiration of this time it is decanted and filtered, and after a further period of six days, it is again decanted. As a flux for this mixture, certain proportions of litharge, borate of lead, and essence of lavender are employed. These are all mixed up and thoroughly incorporated; and the liquid is then ready for application. Mirrors prepared in this manner are exceedingly brilliant, and the cost does not exceed one shilling per square yard of

glass, a notable degree of cheapness compared with the price of the silver mirrors.

a concise vade-mecum as this little volume.

The Manual of Colours and Dye-Wares; their Properties, Applications, Valuation, Impurities, and Sophistications. By J. W. SLATER, Author of the "Handbook of Chemical Analysis THE title of this book almost renders unnecesfor Practical Men." London: Lockwood & Co. sary any elaborate review of its contents; and all we need say is that Mr. Slater appears to have handbook what its title asserts it to be. The done his work well, and has really made his object of this manual is to furnish an account of the chemical products and natural wares used in dyeing, printing, and the accessory arts, their properties and applications, the DOES ALCOHOL WARM THE BODY?-Professor means of ascertaining their respective values, ject:-1st. That alcohol lowers the heat of the body, present. Recent years have been so fruitful in Bing has come to the following conclusions on this sub- and of detecting the impurities which may be and that it preserves life in febrile affections, where the novelties, and have witnessed so great an enlargetemperature rises very high, by its antipyretic properties. 2nd. That extreme depression of the vital ment of the resources of tinctorial art, as to powers in febrile cases is most frequently dependent render older authorities defective and, in some upon the temperature of the blood, and passes off when measure, obsolete. Mr. Slater's work is a strictly it falls. 3rd. That the number and strength of the con- scientific manual, as he relies on the chemical tractions of the heart always rise under the use of alcohol. Whenever, therefore, such an effect would be methods of determining the nature and value of injurious, alcohol would be an improper remedy. 4th. the different dye-wares, rather than upon the That in all probability alcohol lowers the temperature judgments formed by brokers and consumers by the retarding influence it exerts over the oxidizing process. after a cursory examination of the article.

roundings, favourable to the spread of disease; small-pox and scarlatina are always present in England, yet it is only occasionally that the sporadic cases multiply so greatly as to become epidemic. Thirdly, a medium for the conveyance

of the contagious matter to the individual or some
part of him, where it can easily enter his blood; it
seems probable that most of the zymotic poisons
enter by the mouth. Lastly, an individual in a state
fit to receive the germ of the malady, and allow it
to multiply.

for the spread of these contagious diseases, the
Knowing that these four conditions are necessary
shortly alluded to.
ineans at our disposal for their prevention will be
With regard to the zymotie
substance, the agent which most effectively des-
troys it is heat. In Egypt, the spread of the
plague is always arrested after St. John's day, from
the intense heat which then arises. A temperature of
120° Fahr. will destroy the contagious material con-
uninjured after exposure to so low a temperature.
tained in clothes, papers, &c., thus most conveniently
disinfected, the most delicate fabrics remaining
Several chemical agents are said to have the power
of altering or changing the composition of the con-
tagious material so as to render it innocuous.
Amongst these are especially to be mentioned car-
bolic acid, chlorine, and nitrous acid.

The state of the surroundings is very important, but unfortunately little is known, of the meteoro

* Written by J. WICKHAM LEGG, M.D., and extracted from The Student.

have been got rid of. The disposal of water and other fluids which have been used by the sick is a matter of some difficulty. It is without doubt in the highest degree immoral to throw such refuse into a drain, whence it may easily pass on and infect others; the best plan seems to be to mix all these fluids with a solution of chloride of zinc, or carbolic acid, and then to have them deeply buried in the earth with a quantity of disinfectants, far away from any wells or sources of water supply to any human habitation. If the refuse materials are more solid than liquid, they should be completely destroyed by fire.

logical changes which accompany an epidemic. A temperature of 32° Fahr. seems to check the spread of some contagious diseases, but the whole of our information on this point is most meagre. One of the surrounding conditions is known to be extremely important-the dilution of the contagious material with fresh air-this is without doubt, the most important agent that we possess in checking the progress of a contagious disease. Free, efficient ventilation of a house will often protect its inmates from infection from without. The media for the conveyance of disease have been spoken of previously. A predisposition on the part of the individual who is exposed to the contagion; for not every A low degree of civilization sets a low value upon one exposed, is infected. Some persons seem quite individual human life. If we compare the thouincapable of receiving the zymotic diseases during sands of pounds lavishly spent by Government, the whole of their life; while, on the other hand, where cattle alone were concerned, with the small certain conditions of the system predispose to them; sums given grudgingly for the prevention and inmental anxiety, worry, and trouble of any kind ren-vestigation-the first step in the prevention-of der a person peculiarly liable. So do fear of taking human disease, it will be seen how hollow our the complaint, a poor state of health at the time, boasted advance really is. The lives of cattle must great bodily fatigue and exhausting labour, above be protected because they are valuable property; all, the fasting state. A person who has not eaten the lives of men are apparently of little or no for hours will be far more likely, other conditions account. So long as the poor remain in their being equal, to be infected, on exposure to contagion, present wretched and unhealthy condition-a very than one who has just taken a meal of meat and poor population may yet be healthy-and so long wine. We cannot always control our emotions or as the death-rate exhibits little or no decline in secure a tranquil and happy frame of mind; but at each succeeding year, so long are we on the moral the worst, most of us can afford a dinner and a dose level of barbarians in disregard for human life. of stimulant. After exposure to infection, a glass This deep stain on modern civilization, the entire of sherry, or brandy and water, is said to prevent neglect of the sanitary condition of the poor, can the complaint from taking root; it would always be only be wiped away by a great effort on the part of well to try this remedy when a person has been society in general, by the framing of laws, which near a source of contagion. shall be no half measures-the curse of English sanitary legislation—but which shall effectually and at once remove this evil from amongst us.

Amongst the poor, the want of good food and clothing, the indifferent light which does not allow them to see the dirt about them, and which they therefore do not remove, the overcrowding and bad ventilation, all render them exceedingly predisposed to the acute specific disease. Accordingly we find THE APPLICATION OF PHOTOGRAPHY TO that an outbreak of zymotic disease always makes head among the poor first; amongst them it gathers its strength and multiplies its points of contagion

before it attacks the rich man's family. Indeed, there is one disease-typhus fever-which is unknown except among the extremely destitute; clergymen and doctors occasionally die of it, their profession obliging them to visit the sick poor, but under no circumstances does it ever spread among people moderately well to do.

After a consideration of the preceding remarks, the question, "How may zymotic diseases be prevented?" may be more easily answered. Individual action can do little; it is to the State that we must look for efficient interference for the suppression of these complaints. With our English notions about the liberty of the subject it will take years of active teaching and reiteration before any government will be sufficiently interested to make laws which will perhaps seriously interfere with the present prerogative of every English subject to spread infection. It has taken seventy years for the English Government to realize the value of Jenner's great discovery, and to take steps to protect the community against periodical outbreaks of small-pox. It is to be hoped that another seventy years will not elapse before something is done to stop the spread of scarlatina, measles, or typhoid fever. Laws compelling the drainage and water supply to be at least effective, and forbidding the frightful overcrowding of dwellings which now prevails in every large town, ought to be made; every case of zymotic disease ought to be watched by officers of health, since that one case may become the centre of extension to the whole town, country, or even kingdom.

Individuals may, however, do a little in preventing these complaints, especially in their own households, but their exertions can scarcely reach beyond this. In the first place, let the water that is used for drinking be most carefully seen to at all times. No one should buy water of a company the purity of whose source of supply is at all questioned, for water that looks, smells, and tastes perfectly good may convey the deadly poison of cholera or typhoid fever. The same consequences ought to follow the sale of unwholesome water to the public as follow the sale of unwholesome meat or vegetables; or, rather, the punishment should be greater, because the effects are more widely spread.

Monsidered as

MILITARY PURPOSES. ODERN warfare may in many respects be so many applications of science. Not only is war matériel designed and manufactured nowadays upon the most approved data, and according to theories worked out with mathematical accuracy, but a large section of our soldiers are educated in such a manner as fully to appreciate the value of their resources, and so to overcome difficulties which years ago would have been regarded as impossibilities. No instance demonstrates this more satisfactorily than the recent Abyssinian expedition, which, whatever may be said of it as a campaign, cannot but be regarded as one of the most wonderful feats of engineering accomplished in modern times. The nearer warfare approaches perfection, the more decisive, and therefore less cruel it necessarily becomes, as witness the brief duration of the wars of late years on the Continent; and for this reason the improvements in warfare effected by science cannot by any means be regarded as a misapplication of knowledge.

Our present remarks bear reference to the applications made of a very modest branch of science, if science, indeed, it can be called, our object being to demonstrate the many uses made by the War Department of photography. In the special application of this art-science to military matters, our Government is certainly in advance of others, if we except, perhaps, that of France. No less than three establishments have been organized in connection with the army in which photography is extensively practised, the most important of them being the General Establishment at Woolwich; but, besides these, there are again many Royal Engineer stations, both at home and abroad, which are furnished with photographic requisites and employ the camera for divers purposes. At Chatham, the photographic establishment assumes the character of a school of instruction, at Southampton it forms an adjunct to the Ordnance Survey Office, while at Woolwich, of which department we desire more particularly to speak, the duties performed by aid of the camera are as various as they are numerous. For registering patterns, recording experimental results, imparting military instruction, and for other purposes too multifarious to enumerate, photography is extensively used, the faithful accuracy One of the most important means of prevention of sun pictures, as likewise the facility with which is also within the reach of individuals; it is quite they are produced, causing the art to be eagerly emsimple, needing no apparatus or chemicals, and is ployed in any way where it can be made available. the free and complete ventilation of all rooms and As an example of the value of photography in inpassages by means of windows opening on the ex-struction, we would cite an interesting scries of ternal air, assisted, where there are opportunities, pictures taken to illustrate ordinance drill. This by fires in open grates. This method yields to none in efficiency; it is of far more use than any chemical means of disinfection, useful though these may be the only effectual plan is complete and thorough ventilation. When a member of a household has been seized with a zymotic disease it is most important that no communication should be held with the sick room other than is absolutely necessary; everything which comes from the sick bedside, or which has approached the sick man should be immediately destroyed with fire. When

series comprises upwards of one hundred views, and demonstrates the practical working of the various kind of guns, mortars, rockets, &c., in the service. One picture, for instance, will illustrate the command "Prepare for action;" a gun will be shown surrounded by a group of artillerymen in the positions they have been instructed to occupy on the issue of that order, each man having his respective number attached to his cap as a distinguishing mark. The next illustration in the series is probably that of "Load," and the next again "Fire,"

gunner or number, for it must be remembered that in gun-drill every man is told off to a particular number and entrusted with a separate and distinct duty. Thus, on the promulgation of any new system of drill, or of any modification in the method of working, it is merely necessary for the military authorities to forward pictures of this kind to the different instructors, who cannot fail at once thoroughly to understand the new exercise; and even the rawest recruit who had assigned to him & certain number at a gun would see at a glance the exact position he is to occupy by a reference to the photographs.

Another not less striking instance of the importance of photography in this connection may be given. At the outset of the Abyssinian campaign it will be remembered that several thousands of packsaddles were required for transporting war matériel into the interior. These packsaddles were made in and sent direct from England to Annesley Bay, so that the troops coming from Bombay knew nothing of their construction, nor of the method in which they were to be packed. This ignorance in the hurry of affairs would have been of serious consequence (for a military packsaddle of the present pattern is a somewhat complicated contrivance) had not the authorities at home been fully alive to the subject and foreseen the threatening difficulty. A mule at Woolwich was harnessed and packed, after some experience had been acquired in the matter, in the most suitable and approved manner, and the animal then carefully depicted by the aid of the camera; the disposal of the harness and trappings and the correct way in which the packages were to be carried, were thus clearly shown in a photograph, numerous copies of which were immediately sent out to Annesley Bay and distributed among the officers of the QuarterMaster-General's department.

In recording experimental results photography again fulfils a duty which could not be discharged so rapidly and impartially by any other means. The stout iron-cased shields and armour targets built up of metal plates of different thicknesses, and then fired at by shot and shell of all descriptions, are carefully photographed after each decisive experi ment, and a record of indisputable accuracy thus obtained. With a picture before us of a target, constructed to represent the side of an armour-plated vessel which has been experimented on, we can at once form an accurate estimate of the impression made upon the iron wall by shot of different calibres, while rear and side views of the structure will show plainly the amount of damage which the backing or skin of the shield has suffered. As may be imagined these prints form important illustrations to the written reports made from time to time to the War Office authorities.

The photographing of newly adopted government patterns, whether in the shape of guns, carriages, waggons, mantelets, tents, &c., is also an important section of the work undertaken at Woolwich, as likewise that of producing pictures relating to army equipment, such, for instance, as demonstrate the setting up of cooking apparatus, disposal of ambulances, refitting of ordnance in the field, &c. There is, moreover, the pursuit of photo-lithography to be mentioned, by means of which designs and sketches are copied and transferred to stone for printing off in the ordinary manner.

The subject of working photography in the field is a matter to which much attention has been given at the general establishment, for it will be readily conceived that the simplest and most effective methods of working, as likewise the different uses to which the camera may be put during warfare are questions of very serious study.

The photographic copies, many thousands of which are annually produced and distributed over all parts of Her Majesty's dominions, are not now printed upon silver paper in the ordinary way, but by the so-called carbon or autotype process, a method which produces prints of an absolutely permanent character. Ordinary silver prints are always liable to become faded and stained after the lapse of a few years, owing to the presence in the paper itself, or in the atmosphere with which it comes into contact, of sulphur compounds which attack the metallic silver composing the image. In the carbon pictures, however, no silver at all is present, the composition of the image being a mineral pigment in combination with an insoluble chromium.

Our description of the General Photographic Establishment at Woolwich has been very brief indeed, but enough has been said to show to what an important extent the art is employed in connection with the War Office; the department which we have described is a branch of the chemical establishment of the War Department, which was first organised in 1854, by Mr. Abel, and has gradually become intimately and indispensably connected with every branch of the military service.-Nature.

THE VARNISH TREE. beautiful black varnish which is so much

this is impossible from the nature of the article, as both of which will represent the change in position THE berut the world over is the production of a porcelain or glass, it should be placed in boiling of the men, as one operation succeeds another, and water for several minutes, as soon as its contents the various duties performed in turn by each tree which grows wild in Japan-and China as well.

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