and on a still grander scale in the mountains ad-
jacent to Mont Blanc. At another, forming
promontories and reefs, which stretch far
into the ocean, and render the navigation -
cult and dangerous.

no license to use it had been obtained. We peduncles incrassated and bulbous at the base." notice these points, since they must be of im- If a friend wish to work at the brand he can portance to all future industrial exhibitions. apply a little diluted nitric acid (1 in 5) to the The show is so creditable in itself, and so deeply spores, and carefully observe the effect produced. interesting, that hitches of this sort are blame- He may also test them by sulphuric acid (1 in 3) able in the extreme. Passing, however, from a and sugar. By means of the nitric acid test he The principal species of granitic rocks are those disagreeable topic, we may observe one announce- will probably find that the cylindrical body con- called granite proper, syenite, hypersthenic granitz, ment which is still of interest to workmen. sists of an outer membrane, which is nearly trans-protogine, porphyritic granite, and serpentine There is to be a Workshop Competition." parent, and encloses a number of cells, which Ordinary granite has been described in chap. i "Workmen are invited to enter their names as give the body the appearance of being jointed. and therefore requires no explanation. Syeni competitors. When a sufficient number of names There is, I think, little doubt that these cells are is formed from felspar, quartz, and hornblende, a have been entered, arrangements will be made formed by what we may term hour-glass con- dark- vitreous substance; hypersthenic granit for a series of competitions. The council are also traction of the primal cell-wall, and that the consists of quartz and hypersthene, a green fist willing to arrange for trials of skill in other whole has its origin in the small yellow spores in- crystal; protogine is ordinary granite, in which branches of handicraft, for which intending com- variably found intermixed with the Aregma, and the mica is supplanted by tale; porphyritic petitors should at once give in their names." by some botanists raised into a distinct genera granite is where large crystals of felspar an Here is a novelty deserving of all support. (Lecythea.) The burnet brand differs somewhat mingled with ordinary granite; and serpentine It is, perhaps, the wisest possible use to from that of the bramble as will be seen by the a conglomeration of all kinds of small pieces d make of an international exhibition. And we following description, which we take from Cooke's mineral substance. Granite is a most durabl must add that a most liberal spirit has been" Rust, Mould, and Mildew." "A. acuminatum-rock, and is on this account much used in engi evinced by the English 'exhibitors, who are, of hypogenous, scattered in minute tufts; spores neering works. When granite appears in the course, in a majority. They saw the Italian con- multiseptate, terminal joint acuminate, peduncles form of needles, as in the Aiguille Dru (see Fig. 1), course, they acknowledged its richness and equal." A vast number of most interesting beauty, they gave it precedence. Not that it objects may be secured by dint of careful and bears away the palm in point of newness, or patient observation by any one who cares to use utility, or the method of improving the ease and his faculties to this end. I may briefly allude to comfort of the life of mankind, because it betrays a few before I pass on. Aregma mucionatum, on an ancient origin in its Roman splendour and its roses, differing from A. bulbosum in having Tuscan grace; but that, being most lavish of art, 5 to 7 "cells," in being scattered over the and precious in substance, it stood, as it were, on leaves in minute tufts, the terminal joint being the step of the industrial throne. As to their mucionate and the stalk fusiform. The raspberry own contributions, in detail we must not attempt brand, A. gracile, is not so common-has 7 to 9 to describe them now. They are of an infinite cells, terminal joint apiculate and peduncles variety. Amid Saturday's bell-ringing, trumpet slender. The strawberry brand is more common, flourishes, songs, wedding marches, coming and is scattered in minute tufts, is multiseptate, has going of courtly crowds, crush of people, confusion terminal joint obtuse, peduncles equal, and rejoices of ceremonies, bewilderment of catalogues, ex- in the name of A. obtusatum. The whole of citement of exhibitors, and thronging of visitors these may be mounted dry in shallow cells, or the round the more popular stalls, it would have been spores may be mounted in balsam for minute vain to undertake a critical view of the Exhibition observation-glycerine is better, but is less trustunder its strictly industrial and artistic aspects. worthy as regards permanence, and is infinitely We hold this duty in reserve, however, and it more trouble. The smuts and mildews of our shall not be through want of will if we fail in cornfields are worthy careful notice. The Puccinea rendering justice to deserving competitors. graminis of the learned, or mildew of the unlearned (the latter, by the way, is most indiscriminately used to designate most diverse fungi), furnishes a beautiful object for moderately high power, and abounds on the leaves of grasses. Of Puccinea there are upwards of 40 species to be found on one or another of our commonest plants. "The spores are uniseptate and supported on a distinct peduncle derived from the Greek, and simply means (Berk.). The name is "closely packed," the spores being closely arranged together. The Sedge mildew (this must not be confounded with the smudgy sedge rust (Ustilago longissimus), the polygonum brand, the ground ivy brand, the P. compositatum, P. vinca, most easily to be found. We P. galiorum, are amongst the most common and

I

MICROSCOPICAL JOTTINGS IN TOWN
AND COUNTRY.
No. III.

H. P.

THINK we may now for a short time wander from the sea-shore and pay a little attention to the land-work of microscopy. A few days since, a break occurring in my usual business hours, away from home I strolled along the line of rail, botanizing with a brother microscopist. Our "takes" were not numerous. Orchis maculata, remarkable only for its " pollen masses," secured in large quantities, and this indeed was the real object of our stroll. My companion called my attention to clumps of the burnet (Poterium sanguisorba), and we set to work to search for the very rare brand (Xenodochus THE WORLD: ITS FORMATION AND carbonarius), which is sometimes found on that or on the "great burnet" (Sanguisorba officinalis). In this we were not successful, but we found a great number of leaves bearing another, and a very interesting fungus, the Aregma acuminatum, and also a yellow fungus, the Lecythea Poterium.. Probably as the best season for collecting micro

ANTIQUITY.

BY ARTHUR UNDERHILL.
(Continued from page 362.)

CHAPTER IV.

fungi is now nigh at hand (July to November), II ANNOUNCED, at the conclusion of my last

chapter, that I should in this number treat of the superficial or surface accumulations of the earth; but I have since thought that it would be better to commence at the other end (if I may so express it). I shall therefore proceed to describe the igneous or amorphous rocks, which play so distinguished a part in the drama of creation.

Igneous rocks are divided into three groups or systems, called respectively the granitic, trappean, and volcanic; and each of these systems is again subdivided into different species of rocks, each however bearing the characteristics of its system.

cannot do better than chat for a while about
them. Some of my readers have seen on bramble
leaves in the autumn, certain black spots on the
under side, accompanied with reddish purple spots
on the upper, and have, I dare say, at times
asked themselves some such question as this,
"What causes them?" Let them in the approach-
ing autumn select a leaf so distinguished, and sub-
ject it to microscopic examination. The examiner
must place the leaf on the stage of the micro-
scope, and throw a good light on the leaf by the
bull's-eye condenser. With a half-inch objective,
or a good inch, he will see that the black spots Granitic rocks are easily recognizable from
are composed of small cylindrical bodies, with their appearance, being always of a highly
short stalks arranged in small tufts. With a crystalline character, and from looking like a
penknife let him remove one of these tufts, place it conglomeration of minute particles or grains
on a slip of glass, cover it with thin glass, and (whence the name granite, from granum, Latin
moisten with water or glycerine, and he will see for grain) of different coloured substances. They
that these cylindrical bodies are multiseptate or are found in all parts of the globe, and form by
are composed of a number of little chambers or far the greater portion of its bulk,-here appear-
cells (four), that the terminal joint is apiculate, ing in huge masses of mountain country whose
and that the peduncles or stalks are bulbous at rugged surface is wholly destitute of any vege-
the base. He may conclude that he has found tation of a higher nature than mosses and lichens,
the Aregma bulbosum, of which the technical and which elevates its summit in sharp outlines
description, as given by Mr. Cooke, is " A. bul- far above the surrounding country; there over-
bosum-hypogenous, with a dull red stain on the lying the strata in flat masses of slab-like
upper surface; spores in large tufts" (relatively figure; at once place found in the form of huge
large) "four septate, terminal joint apiculate; pikes, tors, aiguilles, or needles, as on Dartmoor,

at Chamounix, it is evident that it could not have
taken such a shape, if it had been formed in the
open air, and the only way by which it could have
assumed such a peculiar shape, appears to be that
it was originally injected through the strata, as yet
in a soft and yielding state, and was there
gradually cooled down as in a mould; in course
of time, however, the floods and rivers wore away
the softer casing, leaving the hard granite in its
who see it.
present form, the wonder and admiration of all

Trap Rocks are generally found in the form of terraces, from which fact the name trap is derived. The trappean system embraces a great many varieties of igneous rocks, which run from the hardest basalt to the soft and earthy claystone porphyry. Basalts are nearly always found arranged in columns or pillars, and constitute some of the most curious and most beautiful tableaux in nature. (See figure 2.) Staffa (& small

island on the west of Scotland) is a mass of basalt.
and is guarded on every side by these mighty
palisades, whose height is in many places several
hundreds of feet. At one side of the island s
huge cavern burrows under the land, forming, as
it were, a natural cathedral, in which the cluster
of columns supporting the heavy arched roof of
the cave, the immense size of the place, and the
architectural regularity of structure, impress the
beholder with far more awe and admiration tha
the most glorious temple built by man.
Giant's Causeway, on the north coast of Ireland.
is another instance of basaltic formation.

The

Greenstones and clinkstones are other species of trap rocks; they are more granular tha basalt, and do not often occur in columns. Amyg daloid and trachyte are more earthy and rough, and contain crystals of other minerals; trap tu are a kind of igneous conglomerates; claystone porphyries are earthy, with felspar crystals.

All the trap rocks appear to have had a vol

2

some slight acknowledgment for their kindness and courtesy. Among the most distinguished of those who shed the bright light of science on its pages stands "F. R. A. S.," and I wish, like him, to preserve my nom de plume, and thus I trust to exonerate myself from any motives of ambitionindeed, that is a long way behind me now. To interest those who are able to use and enjoy this elegant instrument, and perchance to guide beginners past some of those self-created difficulties into which they are so liable to fall, often from attempting to accomplish, in a few months, that which asks the perseverance and discipline of years-and to pass some wearisome hours usefully I-this is the motive which induces me to write. Enough that the controversial war did long and hotly wage to the vexation and perplexity of players, and to the cost of many talented and eminent men, who sacrificed something even more precious than gold. All honour to each one of them! Once upon a time the flute was a very bad instrument; now it is as good as any one can reasonably desire; from its peculiarly intractable nature, it will never be more perfect than it is, and it must be a man's own fault, or rather the fault of his pocket, if he does not possess a really fine flute. As I cast a backward look at the best years of my life devoted to its study, I cannot help contrasting the flute of 1830 with the flute "of the period," and as I do so, I offer my grateful thanks individually to those who have expended time, patience, talent, and money to make it what it is.

II.-Principle of action. A body M, Fig. 77, laid on the length A B of the plane is acted upon by gravitation Q along the line M Q. The force of gravitation can be decomposed into two: one M O, perpendicular to the length A B; the other, MR parallel to A B. Now M O, or the "normal," as it is called, has no effect whatever as to the motion of M down the plane; hence M R is the whole force to be considered. Therefore a force M R, equal and opposite to M R, will keep M

at rest.

never stand for sin a unless when cos 6 is in a
line like H.
(2.) 6

P

W

P

=

sin a

-m

W sin a

1-m

Р

In

= 1

W

this formula P, Fig. 78, is the power exerted;
its direction is along
the line N P, but for
the moment no in-
tensity is marked by
length of line; W the
weight of the body;
a the angle of the
plane, ẞ the angle of
the
with the
rope,
"length" A B.
proof of this formula B
is simple, and just
represents the amount
of knowledge sup-
posed in this series.
Construction. The
forces P and Q not
being parallel act upon

The

C

FIG. 80:

the body at a point N. в

P'

Draw N O1 perpen

dicular to A B, i.e.,

=

=

known under a special name the principle
virtual velocities. The word "velocity" S
to require force in action, yet it is not so. I
principle is more easily understood by suppos
action for the moment, but it applies in si
fulness to equilibrium, or more strictly is
for forces not allowed to act. Hence in the D
the word "virtual," i. e., the velocity whic
The
force could produce if allowed to act.
mination of what takes place when a weig
raised along an inclined plane shows, in a sul
and comprehensive manner, the main truth
tained in the principle of "virtual velocities.
body on an inclined plane has a certain w
When it has arrived at the top it has moved
a certain velocity through a given perpenda
On the other hand the power which r
space.
it has a certain amount of force, which co
represented by a weight. When the bo
been drawn up, the power, too, has acted
certain velocity, and through a given sa
Take case (1), and let A B = 100 ft., A C
50, P
Hen:
power 5 has
space of 100,
length A B.
only moves
AC 10.

ni.e., the cords form some angle (fig.78) represented by the indefinite quantity n. Cos 6 may be represented by 1- -M. m indicates the diminution of of the value of cos 6. As none of the elements of the plane enter iuto this supposition, an ordinary formula is not possible. But the value of 1 m (cos 6) is at once found when absolute value is given to n. From the inspection of the formula in its general shape, it is evident that as 6 increases P must increase (the divisor cos decreasing) until (3.) Cos 6 sin a-i.e., when the power acts perpendicular to the horizon, then P must be equal to the weight. That the P W power is acting along a persin a is pendicular to the horton when cos 6 easily shown. Draw O V (fig. 79) parallel to A C, the base, which is always taken as horizontal. BAC or a = a. But Now the angle BO V sin a', therefore the to move through a perpendic by the supposition cos 6 angle POV must be equal 90°. For the equaas it must draw the weight over t lity, cos 6 sin a', is only possible when V O P In the mean time the weight y is a right angle, or when P is perpendicular to the through the perpendicular base. That the plane is of no service in this case Now multiplying the power by experience is enough to teach; but there is a space (50 x 10), and the weight by its sp great satisfaction in finding it so clearly indicated (50 x 10), there results an equality (1) 500 W. 500 500; or (2), 500 by the formula: P: 0. Substituting in Hence cos 6 = cos a. But cos these equations the possibility for the actuair (4.) 6 a. A C, the base (fig. 80). (the posse for the esse) of the result, the princr Here therefore again the height of virtual velocities signifies: that in all machse there must be equality between the power, mu may be used instead of sin a. This is another of the ordinary plied by its velocity, and the weight (or work to laws P: W: H: B. The com- be done) multiplied by its velocity. In the frac mon form in which this case is tional form it runs ; the power is to the presented shows the power (the cord) parallel to the base, A C. But the formula work inversely as the possible velocities (r = veproves that the law is general; therefore the locity of P, v velocity of W). Hence (3) P v x force may be applied in any other direction in w 0. This last formula will make intelliwhich the condition (6a) is observed. Hence, gible the general expression of virtual velocithe force may be applied along the line P' Nties" to be met with in books-(p x v) = 0 — which can be so drawn that the angle P F B (3)

This being the first of the machines, it will be very well to state, in a marked way, their object, and to show how in the "present" machine the formula indicates the conditions for the better the general object of these machines is to proattaining of that object. In the plainest terms, duce equilibrium with the smallest possible power. Hence the formula which gives P the least value indicates the most favourable conditions of equiSines and sides opposite being proportional, it librium. There is something unusual to a be

portional to the forces

i.e., the algebraical sum of all the pressures
(forces of power or weight-work) multiplied by
their respective velocities is equal to zero. This
expression is in nothing essentially different from
the formula (2). Instead of P v is the sum of all
the forces which may constitute the sum of P -
sum of its constituent forces, which are also ren-
p v + p' v' + .
dered by the letter (p) with different indices. The
letter (p) is used for all, both power and weight
elements, to express pressure-forces not in action
--equilibrium.

Instead of wr' is the

IV.-Development. Inclined plane uses. Rea The from one point to another raised above it. are no more than very long inclined planes d small angle. Here occurs a technical term to explained-for example: " the road rises 1 in 1: That signifies that at the end of each 12th plane is one higher than at the end of the ceding 12. Suppose 1 = a foot, 1 in 12 siges that the road is one foot higher at the end every 12 feet. The same is the meaning of 11 20, 30, &c. From the principle of the inclined plan, it is evident that the great object in the c

ginner in this view of a formula which, if not minded, may suggest a wrong interpretation of the results. Therefore the least being the best, it is evident from inspection of the formula I., that case (1) gives the greatest advantage; for in that case cos 6 is the largest possible divisor. II. Case (2) comes next as long as it keeps from (4) 6 After 6 = a, at each increase of angle there is a nearer approach to the machine being useless. These conclusions suppose that the plane elements Now sin PNO cos PND (D N drawn per- do not change. How they should change to decrease pendicular to O N) P is also shown by the formula I. sin a (the smaller the angle of the plane), the tion of roads is to make the incline or "gradients" as they are now called, as gentle as pushe, i smaller will be the quotient P. Here is the a as small as circumstances will permit. Of great practical experience: that the less the height of inclines there are some wonderful examples. The the plane the better. II. The greater cos 6 (the longer the plane), the greater the divisor, and temporary railway over Mont Cenis is the greatest ever yet attempted with success by a lemotive. consequently, &c. This falls back into the first, The gradients " of the zig-zag inclinei padeS are 1 in 12 and 1 in 13. The aids to the poset in practice: the height remaining unchanged, the III. No the steam will be brought in under their o longer the plane the less the angle. lengthening of the base will give increase of in India had before the Mont Cenis the gr power unless the angle be changed, for the rela- principles. The railway over the Western Gha lation of sin a and cos. a remains the same. incline. Crossing the Western Ghauts, i &c. The conThese elements of the inclined plane serve to in-miles there is an ascent of 1,800ft.* ditions of equilibrium, without the help of simple troduce a most important consideration regarding trigonometry, must be studied in a set of different cases, each having its own formula and special train of reasoning; with the formula just established, all possible cases are included in three or four suppositions. The simple evolution of these will show what a quantity of knowledge is securely stored up by remembering the short formula (1.) 6

W

all machines-namely, what is gained in power is
lost in time. Thus here, when the plane is longer
with the same height, there is a gain of power,
but a loss in the time required to move the body
to the same height. Suppose the plane 500 ft.
long and 10 ft. in height, the body has been only
raised 10 ft. after the time spent in moving over
100 ft. Were the plane but 30 ft. long, with the
same height, there would be a loss of power (P
0,-i.e., the cord forms no angle, is should be greater), but there would be a gain in
parallel to A B (fig. 77) cos 6 time. This gain or loss suggests the announce
A B the length of ment, even now, of a principle most important in
radius
the plane. Sin a in this sup- practical mechanics, which is usually explained
position may be replaced by the first, in another place. Still as a rigid demon-
height (H) of the plane. Hence stration of it cannot be given even there, its
the common formula (c). Sin a simple explanation is well obtained by means of
is always the height, but H can the inclined plane. Such is its value that it is

=

=

The raising of great weights from one lev another is the second use of the inclined pl” Blocks of stone from the quarry, and ships ha up into the dockyard are the chief practisi amples on a large scale; on a small scale exan are without number, and too obvious to ro special mention. On the Morris canal, New Jets U.S.A., there is an example of a novel use of t inclined plane. Instead of a series of "luck this canal has a series of twenty-three inde planes, varying in height from 35ft. to 10 The boats (carrying some 70 tons of coal drawn to the top of the plane by a rope

passes almost as quickly over the plane as over so fact, we find Ptolemy speaking of Polaris as "the tary acquaintance indeed with mathematics to much level water.* star at the end of the little Bear's tail," Regu- enable any one to see that while the configuration lus as "the Lion's heart," &c.; and it is curious of the stars will correspond pretty accurately that this mode of description actually survived where the cube touches the sphere, i. c., in the to the time of Halley, our second English Astro- middle of the maps, when we get up to the bounnomer Royal; albeit, nearly 180 years before, daries of the maps, or to the edges and corners of that very voluminous writer, Piccolomini, in a our imaginary box, the distortion becomes unwork on the fixed stars and the sphere, had desig- manageable, and well known stellar configurations nated the stars of each constellation by letters, are twisted and cramped up so as to be unrecogand even inserted some rude maps of them thus dis-nisable. tinguished. Some 50 years later than Piccolomini, Bayer gained what has been called "cheap immortality," by a revival of this idea, and attached to the stars in each constellation, in the order of their brightness, the letters of the Greek alphabet, commencing with the capitals, going on to the small letters; and finally, on exhausting them, using Roman type for the remaining components of the constellation. The recognised constellation makers are Aratus and Ptolemy, and (perhaps) Bayer, Hevelius, and Lacaille. Others, including Halley, have made confusion worse confounded by poking in foolish little asterisms into the midst of a scheme already most exceedingly involved; and by adding where they might very well have subtracted, only made bad worse. There can be no doubt of the use of constellation-figures as a kind of memoria technica for those whose object it is to acquire a naked-eye acquaintance with the heavens; but those of Ptolemy were sufficiently confused, and interlaced in a sufficiently perplexing way, without requiring modern help to still further complicate the artificial divisions of the face of the visible sky.

Sub-application I.-The wedge I., an inclined plane forced under a weight, has the same action as if the weight were drawn up along the plane. Some of the most ordinary uses of a wedge show that it is no more than an inclined plane driven by blows under some weight; or in more general terms, at an angle to some forces to be overcome. II. The wedge, when used for lifting, is a single inclined plane, the force is applied parallel to the base, by blows on what is called the "back" of the wedge (the "height" of the plane). For all effects of separation the wedge is a double inclined plane III. Theoretically, therefore, the wedge should be reducible to the formula of the inclined plane. But practically, the wedge requires attention to forces, the power of which can only be calculated more or less approximately. Thus the power (P) is usually exerted by a blow, the exact value of which it is very difficult to estimate. Then there enter elements, some of which it is almost impossible to bring under the control of mathematical formulæ. A good notion of the difficulty may be formed by reading in the ENGLISH MECHANIC, April 15, the article on the wedge, in the valuable series of papers on Friction, by Mr. C. Draper.

REVIEWS.

A New Star Atlas. By R. A. PROCTOR, B.A., F.R.A.S. London: Longmans, Green, & Co. 1870.

F we may credit Clemens Alexandrinus, the

ness.

The most prominent characteristic of the admirable atlas the title of which heads this notice, is the manner in which this grave defect is obviated, by the assumption that the sphere is contained not in a cube, but in a regular dodecahedron, thus dividing it into twelve equal and similar spherical pentagons, and by the employment of what is called the equidistant projection. For a detailed account of the method adopted we must refer to the excellent and readable introduction to the atlas itself. In practice the pentagonal boundaries of the maps are replaced by their circumscribing circles, so that the respective maps overlap, not at their extreme edges, but well within the area delineated. It is, of course, physically impossible to reproduce a spherical surface with absolute accuracy on a plane; but the amount of distortion in the particular species of projection adopted is so very nearly insensible as, for practical purposes, to vanish. It is only needful to compare the twelve circular maps which constitute the atlas with the two key maps prefixed to them, and drawn on the gnomonic projection, to see the enormous superiority of the former.

The first stellar maps, worthy of the name, were those of Bayer, which appeared in 1603. The scale of the maps being that of a 20in. Flamsteed's "Celestial Atlas," published in 1729, globe, affords ample space for the delineation of consists of 28 charts, and was the principal one detail, and the consequence is that many thouemployed by astronomers during the last century. sands of objects are charted without the slightest Bode's atlas, published in Berlin in 1805, contains confusion. Some rude notion of the legibility (if between 17,000 and 18,000 stars. Harding's, in 27 we may employ that word) of the maps may be charts, gives more than 50,000. Since then gathered from the statement that on map 2, a and Bessel's zones and Argelander's "Uranometria 3 Andromeda are 2.5in. apart. These maps have Nova" have appeared. Weisse's reductions of been very beautifully reproduced in photo-lithoBessel's zones contain nearly 32,000 stars, as-graphy by Mr. A. Brothers, F.R.A.S., to whom cending to the 9th magnitude. The chief excel- high praise is due for his share in the matter. lence of Argelander's maps consists in their con- Mr. Proctor has not, however, confined himself taining a thoroughly revised scale of magnitude of to the manifest improvements we have indicated; stars, they having been by no means previously all a very cursory inspection of these maps will reveal classed exactly according to their apparent bright- many others. He has discarded, the rays which A large atlas has also been brought out in previous uranographers have always put round Paris, by M. Chas. Dien, within the last few the images of the stars, and represents them as years. A great drawback to the popular use of circular dises. A very simple and ingenious methe majority of the works published during the thod is employed, too, in indicating the various present century is found in the fact that the stars magnitudes, and we may add that the adoption of in them are dotted down without note or symbol, Sir John Herschel's photometric scale enables and suggest the idea that a brush full of Indian him to indicate the relative brightness of the ink has been rapidly drawn across a small tooth leading stars, an exceeding help to beginners, comb, while the latter has been held over a sheet who may well have been often puzzled to see of white paper. From 1830 up to the present the smaller of two stars in a map the brighter one year essentially the maps of the stars which have in the sky. been in use for ordinary purposes in England are those of the Society for the Diffusion of Useful Knowledge, and, with certain reservations and exceptions, very excellent they are: that, however, they are defective in more than one point of detail everyone who has ever used them will admit. A compilation from them came out about the year 1842 under the title of Middleton's Celestial Atlas;" this contains a most valuable adjunct in the shape of corresponding blank maps, presenting the stars white upon a dark ground, as we see them in the heavens. A very picturesque "Atlas of Astronomy" too was produced (under the editorship of Mr. J. R. Hind, F.R.S., superintendent of the "Nautical Almanac ") some fourteen years ago by the great Scotch geographer,

In the maps themselves, the constellation figures are abandoned. Deferring, however, to popular prejudice, our author has retained them in the index maps, where we may see a brown bull with bright yellow horns butting at Auriga, who is appropriately got up in pea-green.

The names of the constellations are put on small labels in those parts the most free from stars, and Colonel Strange's capital forms of numerals are used throughout. The hour circles and parallels of declination are marked in continuous lines-the lines of latitude and longitude in dotted ones. A very simple arrangement of arrows indicates the processional motion for 100 years, so that the maps serve, and will serve, for any epoch. The symbols employed to indicate nebulæ, clusters, simple description, and the whole of the detail of co-ordinates and nomenclature, while perfectly sharp and distinct, is yet so relatively faint as not

I wet division of the bus coustella by. If is beautifully printed binary and multiple stars, de, are all of a very

tions was made by Chiron some 1420 years before and got up. The most glaring and obvious fault the Christian era. Pliny, however, speaks of in all these atlases, without any exception, is the astronomical observations found on burnt bricks great distortion which exists when we recede from ("coctilibus laterculis") among the Babylonians, the very middle of the maps. To take the Useful to distract the eye from the various discs repreascending more than 2200 years B.C., while Knowledge Society's maps as a typical example-senting the stars themselves. Alexander sent to Aristotle from Babylon a they are drawn on the six interior surfaces of a Probably a difference of opinion may exist as set of such observations reaching 1900 years back; cube, on what is known as the gnomonic projec- to the expediency of the alteration made in the and it is asserted that the Chinese and Indian ob- tion. A popular notion of this construction may servations extend back to a more remote peri od be gained if we conceive the stars to be accurately still. Reference in the Bible too, as in Job delineated upon the internal surface of a sphere, xxxviii., 31, 32, to individual stars and groups, this sphere to be placed inside of a cube or box indicates that various stellar configurations had whose sides, lid, and bottom are tangent planes to been remarked, at a very early age. Knowing then, the sphere (or, as one might say, the cube exactly as we do, that hieroglyphics, or pictures, have holds it), and the eye being placed at the centre always preceded writing, as the means of record employed by nations in their primitive emersion from barbarism, it seems only natural to believe that figures of star groups, of some sort, must date from the very hoariest antiquity. Quitting, however, the region of conjecture for one of ascertained

* Scientific Review, Vol. ii., p. 308.

of the sphere, lines drawn from it through the
various stars and produced until they pass through
the faces of the cube, then the places of the stars
will be marked down upon the inside of those
faces at the points where our imaginary lines pass
through them, and upon dissecting the cube we
shall have six square maps representing the whole
of the visible heavens. It needs a very rudimen-

names of some of the constellations by Mr. Proctor. The chief objection to such alteration would seem to be that it throws a needless difficulty in the way of the beginner, who may be searching for some object from its name in a catalogue. For example, the incipient possessor of a "Nautical Almanac" might not quite recognize 12 Canum Venaticorum ina Catulorum," nor Procyon in a Felis. And while mentioning this last asterism by the way, we remember that some former starcollector actually did insert a constellation Felis, somewhere under Hydra. We may add too, that if it be needful to alter Ursa Minor at all, we would indicate Ursula as more suggestive of its old appellation, than merely "Minor," a name

equally pertaining to Leo Minor and Canis Minor, both of which figure here under a changed no

menclature.

The atlas is strongly but handsomely bound, is of a handy size for reference, and is sufficiently elegant in its external appearance to render it an ornament to any drawing-room table. For the especial purposes for which it was designed it is certainly not only unsurpassed but unapproached by anything which has hitherto appeared; and, while it will doubtless soon be found in every fixed observatory in the kingdom, its peculiar adaptation to the wants of the astronomical students unprovided with graduated instruments, will commend it to that large and increasing class of observers who merely possess moderate telescopes on ordinary stands. They may accept our assurance that in no other way can they acquire a familiarity with the face of the celestial vault so easily and pleasantly as through the medium of the work of whose leading features we have endeavoured to give some indication.

On the Manufacture of Beet-root Sugar in Eng-
land and Ireland. By WILLIAM CROOKES,
F.R.S., &c., Editor of the Chemical News.
London: Longmans.

THE manufacture of sugar from beets is an in-
dustry which bids fair to become established in
the United Kingdom; and from a conviction of
its great national importance Mr. Crookes has
been induced to prepare this elaborate work
for the press.
In the year 1747 Marggraf,
a Berlin apothecary, made known at the Royal
Prussian Academy of Science the fact that beet-
roots contained sugar identical with that derived
from the sugar-cane; and although his proposals
to extract it on a large scale, owing to a variety of
causes, did not then meet with any success, with-
in a century after its announcement his discovery
became an important industry, and the extraction
of sugar from beet is now one of the recognized
manufactures, not only of Germany but of France,
Austria, Russia, and Belgium. The original
plant from which the beet of agriculture was de-
rived grows wild on the coasts of the Mediter-
ranean, in Spain, Dalmatia, and some parts of
France. It is an unsightly bi-annual plant,
known to botanists as the Beta maritima; and the
common red beet is a variety of the same genus.
The percentage of sugar contained in beet-roots
varies considerably with the nature of the soil, the
method of culture, and the kind of seed used. In

always preoccupied with the use of formulas deduced from the theory of flexion, did not attach great importance to the phenomena attendant upon rupture, and the majority neglected to extend the IT experiments beyond the limit of elasticity where the formulas cease to be applicable. The observations of Hodgkinson sensibly enlarged the field of the old experiments.

All these results have led to more exact determi

ing, and carried on simultaneously. Thus a Mr.
Robert Campbell has erected a large beet-root distil-
lery on his estate at Buscot Park. This agricultural
establishment comprises about 5,000 acres of land,
and the distillery supplies sufficient refuse to feed
12,000 sheep and 2,500 oxen. Mr. Campbell has
obtained on the first trial about 40 tons of beet-
root to the acre, with from 10 to 12 per cent. About this time the extended use of metal in
of sugar. A French manufacturer, M. Cham- construction upon railroads, and especially the can
ponnois, has succeeded in extracting the whole of struction of the great iron bridges, Conway and
the sugar contained in the beet, and converting it Menai, were the occasion of new experiments, very
into alcohol, and in keeping in the residuary pro- numerous and interesting. The account of the
duct the whole of the alimentary principles which observations, generally extended to the point of
the beet contained. The value of the spirit ex- rupture, is contained in the monograms upon the
tracted is not the only return for the original out-construction of these great bridges of Stephenson.
lay; for on the land belonging to the distilleries nations of the specific constants relative to ir
of which Mr. Crookes gives statistics, the yield of They show that iron obeys the theoretic laws
wheat was increased from 19 hectolitres to 27 transverse flexion for slight deformations; that
per hectare; and whilst these farms were found coefficient of elasticity is reduced in very larg
capable of rearing only 25,386, and fattening works; that the resistance of iron to crushing s
6,955, head of cattle, they now rear 51,449, and generally less than the tensile resistance.
fatten 46,656 head, besides giving employment to reverse is true of steel. Besides, the limit of
a vastly increased number of workpeople.
elasticity of steel is greater for compression than
for tension; while in wood and iron the limits are
the same. The coefficient of elasticity for steel is
not the same for compression as for extension-3
singular anomaly, which makes rigorous calculation
of flexion very difficult. MM. Collet-Meygret and
Desplaces have deduced an interesting consequence
from observations made on the Viaduc de Tarascon :
it is, that in steel the sections do not show every-
where an equal elasticity, so that it is necessary to
distinguish the shell from the portions near the
surface, giving to each its special coefficient. The
line of demarcation between the two regions seemed
to be difficult to trace rigorously. Iron drawn into
wire of a small diameter presents analogous pheno
mena; so that it has long been known that iros
wires contain elements that resist extension-
property utilized in the construction of suspension

Mr. Crookes gives the following estimate of the expenses of a sugar manufactory, the first cost of which he puts at £13,157, and considers capable of producing at least 1,200,000lb. of raw sugar. The amount required for labour and material would be £12,620, which, together with taxes, insurance, and interest on capital, would make a total expenditure of £13,980. The realization from this outlay should, reckoning only 8 per cent. yield of sugar, reach £20,470, thus leaving £6,490 as the profit! Mr. Baruchson however, taking the yield of sugar at 64 per cent., estimates the return at upwards of 24 per cent. on an outlay of £30,630; but if the roots yield 8 per cent. of sugar, the extraordinary profit of 48 per cent. will be the result. Even taking these state-bridges. ments cum grano salis, it is sufficiently evident Hodgkinson has made a special study of the that profitable employment can be found for resistance of pieces under pressure at their abutmoney lying idle; and we can confidently recom-tings; among these, upon steel columns. mend this book to any capitalist in search of a remunerative speculation. Mr. Crookes has spared no pains to obtain all the most recent information; and his work contains, we imagine, the completest account of the manufacture of beet-root sugar ever published.

THE RESISTANCE OF PRISMATIC

in a succinct form.

SECTIONS.*

His em

pirical formulas give the breaking load of a hollow column in terms of its height, and its external and internal diameters. The load which a column can safely bear is fixed at a sixth of the breaking load given by the formula. He has shown by numerous experiments the influence of the shape of the base, whether flat or round; and also the effect of rentement. He has substituted a formula for wood instead of that given by Rondelet, and shows that the load supported by oak varies nearly as the fourth power of the least dimension divided by the square of the length. M. Sove has substituted more convenient formulas for solid columns of steel or iron; they lead without difficulty to the cholec between iron and steel for a column of given dimensions.

The observation of the vibratory motion of elastic solids leads to the determination of the coefficients of elasticity. It is the only method ap plicable to their plates or to wires. To this class of researches belong the experiments of Wertheim, and those of M. Phillips upon the spiral reglat

In a scientific point of view the experiments upon the resistance of materials have shown that the hypotheses assumed in the solution of the problem of the deflexion of beams cannot be re garded as absolutely true. It is almost impossibl to determine the limit of elasticity. A metall bar, once subjected to tension, does not return to precisely its original form when the tension ceases, and its elasticity has undergone a certain alteration. The limit of elasticity, as understood in practice, is that limit at which alteration becomes sensible by the coarse methods of experiment; but as these become more precise, it is seen that this limit gradually diminishes, and it would without doubt disappear if the processes were perfect. The limit of elasticity is certainly of great importa but one should not pretend to determine it will a precision that cannot be applied in a practical problem. Late experiments have shown the 3istence of certain gaps in the theory, without filling them. They have shown the great com plexity of the problems without suggesting the means of getting rid of it; so that the old theory of deflexion remains the only guide that can be confidently followed, while we wait for the perfect solution which is to come from future investiga tions.

a number of analyses made by Professor Voelcker, IMPROVEMENTS in experimental methods have, he found the amount of sugar to vary from 3-62 during our epoch, kept pace with improveper cent. in a white beet, to 13-19 in a red, the ments in analytic methods. Formerly experiments latter manured with London sewage. Professor were made upon pieces of small dimensions; and Church has found as much as 13-47 per cent. in the constants which were determined were applied Carter's prize nursery sugar beet, and Messrs. to the same materials, whether employed in the smallest or the greatest works. The old experiVilmorin, of Paris, are reported as having seed menters followed this method; Buffon with wood, which will produce roots giving 16 per cent. sugar. Rondelet and Rennie with materials employed in The chief requisites in soil upon which this crop masonry, Barlow and Tredgold with iron and steel, is intended to be raised are a sufficient depth Vicat with mortars. They had in view generally and ready penetrability by the plant. A good the determination of four quantities-the specific friable loam, and all soils which grow potatoes in gravity, which enters into the calculation of the perfection, are the most eligible for the growth of proper loads, the coefficient of elasticity, the limit A fifth beets. Clay lands will be found equally well of elasticity, and the breaking weight. adapted, if the soil is judiciously prepared. It remained to be determined, that is, the limit of the load for actual construction consistent with would, of course, be bad farming to cultivate the durability. These experiments, repeated by a great beet two years in succession on the same piece of number of observers, under the most diverse conground; but it forms an excellent rotation crop ditions, have thrown great light upon engineering with wheat, clover, and oats, or with wheat, flax, art. The tables of Genieys, in the section on the and turnips, all of which, according to Mr. Baruch-resistance of materials, present an excellent résumé son, are more abundant when beet forms the alternate crop. That this is especially the case The problem of the reaction upon pieces at their with wheat all who have made the experiment supports which leads to particular cases, has been studied experimentally; and Rondelet, in his "Ar can testify. One peculiarity of the beet, and one de Batir," reviewing all the facts collected by his of its great advantages to farmers, is that, added predecessors with reference to the compression of to the fact that its leaves make an excellent fod-wood, has given a practical rule which indicates the der for cattle, the pulp, after extraction of sugar, successive reductions to which the limit of load makes a valuable feed for stock, and according to should be subjected, as the ratio of the length of Prof. Voelcker, although he speaks with some re- the piece to its least transverse dimension is servation, one ton of the pulp as it comes from the increased. It follows from this rule that a piece presses contains as much nutriment which cattle twenty-four times as long as the side of its square can assimilate as 1 ton of the roots before the section upon which it stands, will sustain only half the pressure which it would if reduced to the form sugar is extracted, or as much as 2 tons of common mangolds. of a cube. This subject has been taken up and "In Belgium fattening beasts are sometimes fed upon nothing else but the refuse perfected by the English engineers, whose experipulp of sugar manufactories." A fair allowAmong these experiments the most numerous ance of bean-meal or cotton-cake, and as much and remarkable are those of Mr. Hodgkinson; the pulp as the cows will eat, produces both abund- results of which were published in 1846, and which ance of milk, and milk of good quality." Pigs were translated in 1855 by M. Pirel in "Les AnnalesHAT, then, is the way in which the contagious matter is conveyed? Chiefly by will also do well upon it, if they likewise re- des Ponts et Chaussees." The experiments of emanations from the sick man. The clothes which ceive barley or pea-meal, or a mixture of both. Hodgkinson were intended to determine with pre- he has worn, the bed on which he has lain, the Having seen that the cultivation of the beet cision the extreme resistance of steel to traction, to furniture, carpets, and curtains of the room u must be profitable, we will proceed with Mr. flexion, and to transverse strains, and to deduce which he has lived, all become the recipients of the Crookes to inquire into the pecuniary aspect of the from the observed phenomena the best form to give contagious material, retaining it for months, or manufacture of sugar and spirit from beets. Of to solids made of this material. The old observers, carrying it with them for miles. The contagious these, the latter seems the more profitable, but * Translated from " Exposé de la Situation de la the distilling should be connected with the farm- Mécanique appliquée."

ments we shall now notice.

ON ZYMOTICS.*
(Continued from page 394.)

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