The English Mechanic

AND

MIRROR OF SCIENCE AND ART. Europe.' War has never done anything, never

FRIDAY, AUGUST 12, 1870.

THE WAR.

A
LMOST every man in Europe feels more or
less interested in the vast and unnecessary
war which is devastating the fairest portions of
Europe. We will not, in these columns discuss
the flimsy pretext for the war. We regard it as a
crime against humanity. There is no doubt that
one of the parties in the strife has been "swift to
shed blood." No one can forecast the results of

war.

the war; we do not, in fact, remember a single historic war that has answered the purposes of its originators. There is, however, one side of the question which wears a hopeful aspect, and which we may record with satisfaction in a scientific journal. Cowper said, "War is a game that, were their subjects wise kings would not play at;" and, for the first time in the history of Europe, we see symptoms of an awakening of the people to a true conception of the measureless evils of The Paris correspondent of the Morning Post says:-"The children of industry begin to question why they should be slaughtered and ruined to satisfy the pride and ambition of sovereigns and statemen. The international trade-unions, the improved education of the working classes, the better knowledge which the people now have of each other-originating in the facilities of railway communication and the interchange of opinion which arises from international journalism—are causes which affect the state of public opinion amongst the working classes of all Europe, calculated some day, if not in 1870, to produce political events of the most comprehensive

2

character."

nor sure."

11

=

87;

according to me, war would be a disaster. I do cell. For cases requiring a large current—as in
not speak in the name of fraternity, in the name plating-or for magnets or coils, it is absolutely
of those sentiments which have nothing to do useless; for a small occasional current, on the
with politics-I speak in the name of interests. other hand, as for ringing bells, household signals,
Experience has confirmed the saying of Montes- &c., it is one of the most useful forms; though
quieu, Men of war have been the ruin of the statement made by sellers that the cell
is calculated to work for "three years
is, of
settled anything. In vain you will be victorious, course, pure nonsense. Like every other form it
in vain repulse Germany and conquer the Rhine; can yield a current equivalent only to the quantity
after victory you will be able to disarm less of material used in it, which will be exhausted in
easily than before the war. You will be obliged a greater or less time according to the work done;
to augment your armies, and the public uneasi- and this depends upon two things-the quantity of
ness will not cease. War is therefore, according the excitant and the quantity of the manganese.
to me, a solution impracticable, wicked-an 148. The peroxide of manganese, otherwise
empiricism. The true solution is peace, peace binoxide, is, on the atomic notation, Mn O
with disarmament, peace with liberty; that two of these atoms enter into the reaction pro-
liberty without which peace is neither glorious ducing Mng O, sesquioxide of manganese, and O
These words were uttered about two one atom of oxygen; and hence, as this oxygen is
years since, and strange to say M. Ollivier is one 16, while the equivalent or our electric unit is 8, it
of the prime agents of the war.
follows that the atom of peroxide is also the unit,
Mr. Gladstone, at the Mansion House, did not as 87 of it by weight yields this 8 of oxygen; but
this is the pure substance, while the commercial
speak in exaggerated language when he said :—
In the name of wounded humanity, in the manganese contains often a large per centage of
name of grieving civilization, in the name of our impurity. In addition to this, as no solution occurs,
religion, afflicted with what it witnesses, I do the action takes place only on the surface of the
record that nothing more deplorable, nothing particles into which the material is divided, and
more dismal has marked, perhaps, the history of hence a considerable portion may escape action;
mankind, and certainly the history of mankind in it is therefore impossible to fix upon any quantity
our time, than this, splendid indeed it may be, as the electric unit; it may range from 100 to 200
but awful spectacle, in which nations of the grains or more. The peroxide is a good conductor;
highest civilization, with institutions the most the resulting sesquioxide is not a conductor, and
perfectly developed, with celebrity established in the same is the case with the corresponding lead
every department of history, with the first posi-oxides hence the action tends to diminish; and a
tions of the civilized world to which it is possible main object must be to spread the material in as
for any nation to attain, are pushing on their thin a film as possible over a large area of con-
troops by hundreds of thousands, and almost by ducting surface. This is most readily accomplished
millions, for deadly conflict, for causes which is by crushing carbon into various sizes, from a pea
down, sifting out the larger and packing them
tightly in a porous jar, in layers, so that the
particles are in firm contact among themselves,
and with a plate or bar of carbon, which forms the
main plate or conductor; the very fine particles
should also be sifted out and ground to an in-
palpable powder, with two or three times their
bulk of the manganese, then mixed with the
intermediate pieces and sifted into the spaces left
mass is formed. When the liquid soaks into this
between the larger pieces till a tolerably compact
and the action is set up, a very large area is thus
exposed, which compensates for the inherent
slowness of the action itself, and reduces the
internal resistance.

it very difficult to appreciate."

The words spoken by Mr. Disraeli in the House of Commons, a few hours after the first sad news reached this country, may form a fitting conclusion to this protest against a wicked and gigantic war:-"I hear, sir, superficial remarks made about military surprises, the capture of capitals, and the brilliancy and celerity with which results which are not expected or conSir, these are events of a bygone age. In the templated may be brought about at this moment. last century such melodramatic catastrophes were frequent and effective; we live in an age animated by a very different spirit. I think a great country like France and a great country like Prussia cannot be ultimately affected by such results; and the sovereign who trusts to them will find at the moment of action that he has to encounter, wherever he may be placed, a greater and more powerful force than any military array-and that is the outraged opinion of an enlightened

A very small surface of zinc is sufficient, and it generally is one or two small cast rods or rolled strips suspended in the outer vessel.

Let us add to this an extract from the Workman's Peace Committee in London, of which Mr. Edmond Beales is chairman, and Mr. W. R. Cremer the secretary:-"Peace is to us as the breath of life. War, that great curse and scourge of mankind, is especially our deadliest foe, for we are ever its most numerous victims, whether as regards the interruption of employment from national distress, or our enrolment in military service. Here, then, comes the question we would urgently press on your immediate and serious consideration. Why should we continue to suicidally furnish the means of our own destruction? Without us, war must cease; for without us standing armies could not exist. It is out of our class that they are formed. Moreover, ELECTRICITY-ITS THEORY, SOURCES, of ammonium will charge a cell, such as the ordi

without our labour the turreted war-ship and the rifled cannon, the needle-gun, the Chassepot, the mitrailleuse, and every other murderous instrument that the perverse ingenuity of man has

world."

AND APPLICATION.

BY J. T. SPRAGUE.*

(Continued from page 388.)

149. THE EXCITANT.-Either common salt or

sal ammoniac are usually employed, though others will answer. It may at first sight seem difficult to say why sal ammoniac at 6d. per lb. should be used if common salt at 3lb. per penny will answer; but as a couple of ounces of the chloride

invented for the annihilation of his race, could 147. PEROXIDE OF MANGANESE BATTERY, that furnished by the sodium chloride. The reason

Various peroxides have been employed
to surround the negative plate and furnish the
oxygen. Peroxide of iron has been frequently
suggested mainly on account of its cheapness and
commonness -common rust, hematite ores
powdered, red ochre, all may be used, and will
answer; but a little consideration of the following
remarks will show that no sort of advantage is to be
gained by the use of iron oxide instead of the per-
oxide of manganese, because it has all the objec-
tions of the latter with no kind of superiority; and,
under the circumstances, cheapness is so very small
a matter as to be quite out of consideration. Per-
oxide of lead, however, possesses real advantages
in that its electro-motive force is very high, and
consequently a battery in which this is used
gives the greatest
form. Its expense, however, is considerable, and
"intensity" of any known
so is its trouble, and I will not take up space by
further reference to it.

neither be fabricated nor made available for their sanguinary purposes. Surely it is time, then, for us to show our power, to prove ourselves a self-preserving power, and also a power for the happiness and blessing of all our fellow-men. We have no wish, whatever may be our individual sympathies, to side with either party in this lamentable war. The working men of Germany, the working men of France, are equally our brethren. It matters not to us, and we verily believe it matters as little to them, who is the prince or person selected by the Spaniards-if they cannot do without a king-to nominally rule over them. What concerns us-what we see and feel is in the enormity that, upon any such a pretext, or for any real or imagined affront, which the arbitration of a few honest and impartial men would honourably adjust in an hour, hundreds of thousands of human beings should be arrayed against each other in mortal combat, about to - steep the fields of France and Germany in their In point of fact the peroxide of manganese is life-blood, and myriads of happy homes be the only one of these substances practically useplunged into measureless misery and woe. The ful. Its employment was first suggested by De la prospect is one that only fiends could contemplate without horror!"

nary Leclanché, and do the amount of work for which alone it is properly fitted for several months, the question of economy dwindles to a very small matter against the higher electromotive force the ammonium chloride gives over for this higher electro-motive force is, that soda. displaces ammonia from its salts, and, of course, in doing so loses force; therefore, when both are de composed the sodium salt has less to yield. In the porous cell; in the other, ammonia is set free and one case, caustic soda is generated within the given off.

operations, it may be useful to give complete in-
As these salts are so largely used in electrical
formation as
chloride, N H, Cl.
to their solutions. Ammonium
ties, the unit is 55 grains, being 127 units per
53.5, or, allowing for impuri-
lb., and at 6d., the cost per unit is 0472 of a
penny. Its solubility varies according to tempera-
ture. My own experiments, which agree with
figures given by various authors, made 1,000 fluid
1,076 grains, and contain 288 grains chloride, or
grains of a solution saturated at 62° Fahr. weigh
5.24 units. Sodium chloride, Na Cl. 58.5, or,
lb., and its cost per unit 0028 of a penny. Unlike
commercially, its unit is 59, giving 119 to the
most salts, its solubility varies very little with
temperature; at 62° its specific gravity is 1.208,
the contents of 1,000 fluid grains, 322 grains, or
5-46 units. Its solution is, therefore, somewhat
stronger than that of the ammonium salt, and
still more so in cold weather.

=

has a tendency to form double salts with alkaline As the action produces zinc chloride, and this chlorides, a deposit of crystals of these is soon found to form on the porous cell, and still more freely on the zinc surface, obstructing the action

It is, therefore, desirable occasionally to remove these by soaking in pure water.

150. Experimenting with a Leclanché cell, which I purchased as about the best type of this form, it gave at first 43°, falling to 30 in ten minutes, and 23° in one hour. Connecting again after several days rest it gave 30, falling to 20 in ten minutes; and, after several weeks doing no work but these tests, it gives 20°. Its charge was about 5,000 grains of solution of ammonium chloride, being about 34oz. of the salt, or 25 units, of which probably only about ten would be effective, the rest being wasted by forming the double salt; and certainly all the work the cell has done would not exceed 2 units; on the other hand, two of these cells would have the same electro-motive force as three Daniels'.

151. SULPHATE OF LEAD BATTERY.-In this we leave the principle of supplying oxygen at the negative plate, but we have an insoluble matter there. It has several forins. Originally the porous cell was filled up with the sulphate surrounding a metallic plate or rod; a patented modification consists of a stout copper wire, to which are fixed several saucers, also of copper, tinned, for holding the metallic salt and preventing its solidifying in the porous cell, so that it may readily be replaced. This is, no doubt, a great improvement, though it is very doubtful whether the sulphate of lead battery is worth improving, notwithstanding that inany simply practical people highly approve of it. Its defects will easily be seen on a little consideration. The electro-motive force is low; the cell is usually worked with common salt for the solution, and in this sulphate of lead is to some considerable extent soluble, hence lead finds its way to the zinc plate and sets up local action. Then the action is expensive; sulphate of lead Pb SO, has an atomic weight of 303, half of which is the equivalent, but as the commercial article is usually very impure, the unit cannot be taken at less than 159, which is about equivalent to the work I have found it to do. This gives 44 units to the pound, and a cost per unit of 1364 of a penny, and hence the cost of working

this cell is

and if we only add 5 per cent. by local action, which is below the truth, we have the cost per unit 1838 of a penny, but as in actual working a large portion of the sulphate of lead would probably be left undecomposed, this would be greatly exceeded, making the cell one of the most costly to work.

The cell has the merit of very fair constancy, and yields a large current for some time, so that for some purposes it would be very useful. One of the patent cells gave me at first, on short circuit 48, rising in an hour to 52, at which it remained for four hours; for some days after I used it in electroplating, after which it gave 37°. and as it was worked fell to 20°. The porous cell becomes clogged with a brown deposit due to the lead, but which is removed by nitric acid, and the sulphate in the saucers swells considerably, so that they should not be filled too full.

1

formed into the sulphate by acting on it with a as a celestial object, whose figure and
cheap nitric acid, which would generate sulphate we wish to determine, the zodiacal Er
of lead from the sulphide direct, and the nitrate of at first sight precisely such an ob
lead formed would be precipitated as sulphate by might hope to deal with most sa
sulphuric acid. A white powder is also formed It is undoubtedly within manageabl
from the zinc, which might be available as a distance. It is often very clearly re
paint.
can view it from varying stations, st
153. THE SULPHATE OF MERCURY CELL.-seasons, and so on. Yet, despite all the
This, which is called from its inventor, the tageous circumstances, the zodiacal
Marie Davy Cell, is of use only in circumstances undoubtedly proved a crux to astrowe
requiring a small intermittent current of great peculiarities have been such as to lead..
force; thus, as it gives no trouble, requires no mulgation of quite discordant theories r
care, and gives off no unpleasant fumes, it is it be said that any theory hitherto
very useful for domestic telegraphs, &c., but it (so far as I know) accounts for al..
is quite useless for employments requiring large liarities of this phenomena.
quantity. Originally, it consisted of a porous
cell, with a rod of carbon packed with the mer-
cury salt; then the porous cell was abandoned,
and a peculiar arrangement employed, in which
the carbon was at the bottom of the vessel; but
now it is usually a simple zinc and carbon pair,
the latter of which extends to the bottom of the
vessel and dips into a mass of the sulphate. The
vessel is then charged with water, which dis-
solves a small portion of the salt slowly, and this
sustains the action, the acid radical acting on the
zinc, the mercury depositing on the carbon from
which it falls, and collects as metal at the
bottom. The action can, therefore, only be sus-
tained at the slow rate at which the salt enters
into solution.

I hope, however, to be able to sha results we have been considering le plete solution of all the geometrical a (if we may so speak), presented by th light. I proceed to consider what the ties are; in other words, to give an ace principal phenomena presented by tha light. Let it be carefully remembere theory to be admissible must give an a all the phenomena; or, at least, not be opposed by a single phenomenon. On this our very difficulties may be of service to enabling us to reject theories which othe would perplex us to choose among.

Speaking generally, the zodiacal light described as a faint tongue of light, visible a the horizon after sunset and before sunrise a extending as if from the concealed sun sloz neighbourhood of the ecliptic. The figures

E

There are two sulphates of mercury. The
proper one is what used to be called the bisul-
phate, now the mercuric sulphate Hg SO,, with
the atomic weight 296. It is obtained by
heating in an evaporating dish two parts by
weight of mercury with five to six of the strongest
sulphuric acid until only a dry white powder is
left. This is the required salt, which hot water
turns into the yellow turpith mineral," and
which does not actually dissolve unchanged, but H
forms an acid salt with the water.
The equi-
valent is half the atomic weight, or allowing for
impurities 150 or 45-66 units per pound, which
at 3s. 4d. per pound is 8750 of a penny per unit.
The cost of working is thus very high, but it is
reduced partially by the mercury recovered, and
for the special purposes for which alone the cell
is useful; this is of little consequence, being
compensated by the steadiness and convenience
of the cell.

154.-There are various other forms of
battery-many useless-some, such as Grove's
gas battery, highly interesting from a theoretical
point of view; others, like the chloride of silver
form, very powerful, but not of general use;
though this latter, where the material could be
obtained for about the value of the silver it con-
tains (as might be at some of the refineries)
would be really a valuable and economical cell.
But I have now dealt with all the forms I can re-
member of any general interest and practical
value, and therefore conclude this part of the
subject, but with the intention of soon describing
a new form which I am experimenting upon. In
the next paper the subject of measurement and
galvanometers will be dealt with.

IF

COMETS AND METEORS.
BY RICHARD A. PROCTOR, B.A., F.R.A.S.
Author of "Other Worlds than Ours," &c., &c.

(Continued from page 435.)

F we are led by the consideration of meteors and comets to a satisfactory interpretation of the zodiacal light, we may be well satisfied with the results of our researches, for there is scarcely a single problem in the whole range of astronomy which presents so many difficulties as this one.

Let me draw a distinction here between two very different classes of problems presented to

Z

Η

roughly what is the usual aspect of the light,
H H being the horizon, E Epse, S the
hidden sun, and Z the veries of the zodiacal
light. But as the position of the ecliptic is con-
tinually changing on our shes, the position of
the zodiacal light changes with it. It is mos
favourably seen, of course, when the eclipti-
shortly after sunset or shortly before sunns
inclined at the greatest possible angle
horizon. The former case happens in F
and March, the latter in October and N

Hence the zodiacal light can
be et l
favourably in the evening hours of s
the morning hours of autumn.

In places near the equator the zodia and in the morning hours, because there. be seen all the year round, both in th is always much more nearly verticalthe and besides, the twilights are shorter.

Wherever the zodiacal light can be set 5 south of the equator-it affects in this ve or within latitudes some 65 degrees 4 neighbourhood of the ecliptic; it sets as as a celestial object in the evening and re regularly as a celestial object in the met so that we might be disposed to conclude a that it is no mere terrestrial phenomenon, not for certain peculiarities presented at t this object. Indeed, as will be seen pre the evidence is far too strong for any question as to the cosmical character of the but there is yet good reason for feeling & where and what it actually is.

152.-The chemical reaction which occurs in the sulphate of lead battery is very complicated, and entirely different from what might be expected. It would naturally be supposed to be similar to that of the Daniel; that the sulphuric radical of the salt would be transferred to the zinc and In the first place the extent of the light ar metallic lead deposited. The action is altogether from time to time. Sometimes its vertes? different; the chloride of sodium is polarized and but 70 or so from the place of the sun, at ei broken up, the chlorine uniting with the zinc, and it actually exceeds 90° or even 100° from 3 the sodium set free at the negative plate. Where When it is remembered that no object travela there is in actual contact with this plate a parwithin the earth's orbit, as Mercury and Vente ticle of lead sulphate, this is decomposed, and could ever appear so far from the sun as the expected action takes place, lead being set the significance of such an extension of the zod free and sulphate of soda formed; but a large part the astronomer. To determine the physical cha-cal light will be seen at once. of the negative plate is not in this intimate mole-racteristics of a certain order of celestial objects Then, again, the brightness of the zodiac cular contact with the lead salt, and the nascent may be a problem which overtaxes man's highest light is not constant. At times, for example. sodium appears to be actually set free so far as powers, whether of observation or of reasoning; is very difficult in our latitudes to see the light > to decompose the water, and at the same time but nearly all questions connected with the posi-all, even on clear evenings or mornings and at t some of the neighbouring lead salt for hydrogen tion or motions of celestial objects seem only to gas is set free to a small extent, which causes the require the fulfilment of certain conditions in swelling of the sulphate, which is partly reduced order that we may resolve them quite satisfacto sulphide instead of metal, and a considerable torily. Those conditions are mainly a certain quantity of sulphide of sodium is also produced. relative proximity of the object in question, and The relative proportions of these actions depend certain motions, either on its part or on our apparently on the rate of the action, and I think own, by which we may be enabled to see it in that the slower this is the more is the salt reduced different directions and so estimate its position. to pure metal.

It may be observed that if this battery were largely used the residuary product might be re

Now the zodiacal light, if we regarded its physical constitution, might prove too difficult a problem for us to solve. But regarded simply

proper seasons; at other times no one can possilu fail to recognise the light when once its positi has been pointed out; while occasionally the list has been so brilliant that it has been mistake for the tail of a vast comet. This happened: March, 1843, during the visit of the great come of that year, when many persons took the zodia cal light for that amazing object. It is doubtless to a temporary increase of brightness of this se that the phenomenon described by Nicephoras, i the following terms, must be ascribed:-"Ther:

as seen at that time," he says, referring to the
ear of Rome's capture by Alaric, "above the
ncealed sun, a strange cone-shaped light, mis-
ken by the ignorant for a comet, but without a
ad. It was a sort of flame, self-luminous, like
lamp, and giving a light altogether different from
ar light.
The place and motions of this
ject changed. At first it was where the sun
ses in spring; then it extended along that part
the zodiac which lies opposite the last star of
Le Bear, its vertex lying westwards. When it
id travelled for more than four months along
e zodiac it disappeared. Sometimes its vertex
as sharper, giving it a lengthened form; then it
came shorter again, &c."
Further, the position of the zodiacal light has
en found to vary, and that in a manner far too
arked to be referred to such variations as charac-
rize the position of planetary orbits. Thus,
st March, Captain Noble observed the zodiacal
hit to be inclined at a considerable angle to the
liptic, its axis seeming, on a rough estimate, to
e inclined some 20° to that circle.

ring far off-say as far as the moon-we ought
always to see the light on opposite sides of the
heavens at midnight, precisely as we see the
moon in all parts of her orbit, except when just
in that small circular region where the earth's
shadow falls across that orbit.

one left us to deal with. As there must be some solution of the problem, and, as every other conceivable solution has failed us, we have a priori reasons for feeling confident that now at last we are on the right track.

To begin with, we need no longer speak of the bodies as hypothetical, since we have already seen that the space within the earth's orbit must be occupied with bodies whose paths carry them far out into space-soine of them even beyond the orbits of Uranus and Neptune. Whether these bodies be comets, or meteors, or associated systems of comets and meteors, we have at least the material we require.

Nor are the variations of the light at all better explained by this theory than the former. Then there remains another theory, according to which the zodiacal light is a phenomenon of the earth's atmosphere, and self-luminous. For instance, electrical discharges, excited as in the case of the aurora, have been adduced in explanation of the phenomenon. Such a theory accounts very well for the variations observed in But, also, we no longer have to account for the zodiacal light, but not at all for the constant variations as a difficulty, but to look for them as features of the gleam. The particular region of a natural consequence of our theory. We have air which would need to be illuminated, in order seen that there must be a continual flux in the that the zodiacal light seen at any one station, condition of the more richly aggregated part of might be accounted for, would be overhead as the family of meteoric and cometic systems reregards places not many hundreds of miles distant, garded as a whole. Even such an observation as and so people at such places should see the light Captain Noble's-exceptional as it doubtless isvertically above them; whereas, at those very would be fully explained if we regarded it as due Lastly, it has been asserted that the zodiacal places the zodiacal light is actually seen situated to the simultaneous arrival of the richer parts ight can be seen at certain seasons, in tropical very much as at the first station. Again, if at of three or four meteoric systems (or even of one Onntries, on both sides of the heavens at once, any one station the evening aspect of the very rich one), inclined about twenty degrees to their n other words, that before the evening glow in zodiacal light were thus accounted for, at other ecliptic. There is nothing in the inclination, in he west has disappeared the morning glow in stations this illuminated air would be due north; the degree of richness involved, or in the conhe east has come into view. Professor Smyth, at others, due south; at others again, due east;currence of three or four such arrivals, which is the Astronomer Royal for Scotland, found this yet all these stations would lie within such limits in any way contrary to what we already know of certainly not to be the case when he observed the of distance that, according to what we know of the nature of meteoric systems. zodiacal light under exceptionally favourable cir- the zodiacal light, the gleam lies actually towards cumstances at Teneriffe; but it may be admitted the west for all of them. Yet again, considering as at least possible (considering what we have only one station, we can perceive no reason why a ready seen of the variable extension of the the illuminated air should have the particular light), that occasionally the zodiacal light may be tongue-figure necessary to account for the aspect thaus visible at opposite sides of the horizon. of the zodiacal light, why it should set in the ay, the astronomer Liais asserts that the zodia-west-or rise in the east-like a celestial body, why cal light sometimes spaus the whole sky from it should follow the varying position of the horizon to horizon. Although this has been re- ecliptic, and so on. We are compelled to abandon garded as incredible, yet I can see no reason why this theory, then, like the rest. SO very definite an assertion respecting the zodiacal light should be rejected; and though I would not care to found a theory upon it, I should be inclined to look with suspicion on a theory which did not serve to explain the observation.

Now let us consider what these peculiarities those at least which are beyond all question-require from us in theorizing respecting the zodiacal light.

The brightest part of the light is seen, whether in the morning or evening, precisely under the same circumstances as the inferior planets, Venus and Mercury; and, undoubtedly, if a multitude of minute planets travelled between the orbits of those planets, we should recognise the diffused light reflected to us by such bodies in precisely those regions, and under precisely those circumstances, in which we see the bright part of the zodiacal light. It needs only an extension of this to the case of a disc of small bodies travelling within the orbit of the earth, or in places extending slightly beyond it, to account for the general aspect of the zodiacal light.

But then we fall immediately into difficulties. A disc, such as we have supposed, would occupy a position (regarding it as a whole) as constant as that of the Saturnian rings, or even more so. We have seen that the zodiacal light shifts very narkedly. We cannot conceive the components of this disc as distributed otherwise than with a ertain general uniformity. So distributed, the ight they would send us would vary little. We ave seen that the light of the zodiacal light varies n a very remarkable manner. Nor could such disc expand or contract to any considerable extent, assuming, as we are bound to do, that its constituents travelled according to the laws of gravity around the sun. But we have seen that the extension of the zodiacal light is very variable.

The difficulties are not diminished by the supposition that instead of a disc the zodiacal light represents a ring of small bodies, as Humboldt imagined.

Accordingly, some astronomers (Heis first, I believe) have suggested that the zodiacal light nay be due to a ring of bodies round the earth; or some of the observations made upon the obect, seem to correspond to this arrangement. It is clear that the earth's shadow would hide he parts of such a ring lying opposite to the sun, and so the visibility of the ring after sunset in the west, and before sunrise in the east, would be accounted for.

But then we fall into fresh difficulties. If this ring is tolerably close to the earth its apparent position ought to be affected by a difference in the position of the observer; yet if we put the

Let us

But there the object is; its light comes from
some region or other; the relations it presents
are very definite. We must not suffer ourselves
to be defeated in an inquiry of this sort.
go over the ground again, and see whether any
one of our theories, though not acceptable in
itself, may not suggest a theory which will meet
all the requirements of the case.

We turn to the terrestrial theory, and find no
hope in that. We consider the theory that the
zodiacal light is due to a ring surrounding the
earth at a greater or less distance, and we are
forced to admit that no shape or dimensions
which we can give to the ring will suffice to ac-
count for the peculiarities and variations of the
object. In fact, we find new objections the more
carefully we consider this theory; it leaves the
symmetrical figure, the systematic rising and
setting, the changes of apparent position with
longitude in the course of the year, wholly
unaccounted for.

Thus we become tolerably confident that it is to some modification of the first theory, according to which the zodiacal light consists of bodies moving around the sun, that we are to look for the solution of our difficulties.

A set of bodies travelling in nearly circular orbits around the sun and within the earth's orbit, failed so totally to explain the peculiarities of the zodiacal light, that though forced to look to that particular region of space for the bodies really causing the light, we are compelled to abandon the theory that those bodies can travel nearly in circular orbits. But if these bodies travel in eccentric orbits, lying yet completely in the sun's neighbourhood (by which I mean, not travelling much further away than the earth's orbit) we have by no means got over our difficulties. Since according to this view the same set of bodies goes always to the formation of the zodiacal light, and since those bodies travel in a short period round the sun, we should have the zodiacal light nearly constant in brightness; and whatever variations there were would take place in short periods. There would be nothing to account for any of the three marked forms of variation considered above; either the variation of brilliancy, and especially the sudden access of brilliancy at certain widely separated seasons, or the change in the apparent position of the light, or the remarkable variation in its extension from the sun's place.

If we give to the constituents of the disc of bodies eccentric orbits of far wider range, we seem to recognize a way-thongh at first sight not a very easy way-out of our difficulties. Anyhow. we may somewhat hopefully regard this new view, since it appears to be absolutely the only

Yet once more,-this theory accounts for even those remarkable observations according to which the zodiacal light has been seen in the east and west at the same time-and if Liais is to be believed, right athwart the heavens, from the eastern to the western horizon. Just as a multitude of minute bodies within the orbit of Venus accounts for the appearance of the zodiacal light in those parts of the heavens where Venus is seen, so the existence of a multitude of bodies within the orbit of Mars would account for the appearance of the zodiacal light along the whole of that arch where Mars travels on the heavens. Undoubtedly it would only be as a very exceptional thing that the meteors would be seen out there, for their general sparseness of distribution outside the earth's orbit (as proved in the preceding papers), and their faint illumination there, owing to increase of distance from the sun, would cause this diffused light to be ordinarily invisible to us, and always exceedingly faint. But from time to time the arrival of the richer parts of several meteoric systems, suitably placed, might be expected to be discernible in tropical latitudes by light such as Liais saw across the southern sky

I have hitherto omitted all reference to what the spectroscope has taught us respecting the zodiacal light. Angstrom's observations that this light gives a speculum of bright lines, corresponding in position to those of the aurora spectrum, may seem at first sight fatal to the theory above enumerated—which would be very awkward, for there remains, as I have said, no other theory to consider. But it must not be forgotten, that nearly the whole light of the zodiacal light might be reflected solar light, and yet its spectrum only show the lines above mentioned; for light collected into a few lines (in this case three) may be discernible where twenty times as much light dispersed into the rainbow-tinted streak, forming the solar spectrum, would be wholly unrecognizable. Now, it is worthy of notice, that one of the lines in the auroral spectrum corresponds to an iron line; and the only way in which we can understand the presence of iron in the upper reigons of our air, is by referring it to the continual arrival of meteoric matter. This being so, electrical discharges, excited by the sun's action, and taking place between the constituents of the zodiacal light, would quite as well account for the bright lines in the zodiacal spectrum as the discharges excited by the earth's much fainter action account for the lines indicating the presence of corresponding meteoric material in the upper regions of our own atmosphere.

If the American astronomers are right in saying that the same lines appear in the spectrum of the corona, we arrive by an independent process at the conclusion involved in the above interpretation of the zodiacal light as compared with what has been already established about the corona, viz., that the corona is simply the richer part of the zodiacal light.

Thus comets and meteor-systems, the zodiacal light, the corona, and the aurora, have been brought into close association. If these views are elucidated by future observations, a series of

hitherto perplexing phenomena will be simultaneously interpreted.

Here, for the present, I take leave of the subject; but at some future time I hope to return to it. I have so far looked at only one aspect of this maay-sided subject; there are others as well worth studying, and associated no less intimately with the economy of the solar system. THE END.

The strata of this group are of considerable the mouth, with its jaw and poison gland. T thickness, occasionally attaining that of 20,000ft., may all be mounted in balsam. and it must therefore have taken a long period for its deposition. The system is of extensive prevalence in Bohemia, Sweden, Russia, Canada, and New York State, and it therefore follows that such localities were subaqueous or submerged at the time of its formation. The fossils of this system are of a very low nature, such as seaweeds; specimens of Radiata called Oldhamia radians, a species of Brachiopod termed Lingula (Fig. 1), and AND Trilobites, which last deserve a some

1

what longer description. Trilobites,
then, were a species of the genus Crus-
tacea. From Fig. 2 you will observe
that their form is that of an oval divided into
three divisions; they are supposed to have
lived in the lowest depths of the ocean, and there
to have existed on

BOVE the metamorphic or primary series lie the secondary formations, and in the lowest system of this group first occur those im-the portant aids to geology-fossils, or animal and vegetable remains.

viz.

molluscs

which were not
provided with a
shelly armour.
But the most re-
markable portion
of these beings
is their eye, which,
although minute
in itself, would,
even if composed

This class is divided into seven systems, (taking them in order of superposition and commencing with the lowest), (1) the Cambrian; (2) the Silurian; (3) the Devonian, or old red sand stone; (4) the Carboniferous; (5) the Permian, or lower new red sandstone; (6) the Triassic, oi upper new red sandstone; (7) the Oolitic, o Jurassic; and (8) the Chalk, or Cretaceous sys-like that of ordi

tems.

The first five of these groups are termed the Paleozoic systems (palæos, ancient; zoos, life), because they contain the remains of life in forms totally different to any existing at the present period. Since it will be necessary in this and the future portions of my treatise to use certain technical terms in relation to the fossil remains of present and bygone races of beings who have peopled the earth, I think that at this stage a little digression for the purpose of explanation would be advantageous, and I therefore entreat my readers to carefully commit to memory the following list of the different genera of animals:

VERTEBRATA (having a backbone) are divided into four orders-viz.: 1. MAMMIFERS (or such as suckle their young), examples, man, dog, horse, &c.; 2. BIRDS; 3. REPTILES; 4. FISHES. ANNULATA (ornamented with a ring) are split up into six orders-viz., 1. INSECTS-examples, bee, flies, &c.-2. MYRIAPODS (thousand footed); examples-centipede, millepede, &c. 3. ARACHNIDES (spiders); examples-spider, scorpion, vermin, &c. 4. CRUSTACEA (shell coated); examples-crab, lobster, &c. 5. CIRRHIPEDS (hair footed); examples-the anatissa-certain beings which cling to the bottoms of ships. 6. ANNELIDES (little-ringed); example-the common earth

worm.

nary animals, be
a wonderful piece
of microscopic
handiwork, is ren-
dered infinitely

more wonderful by
the fact that it
is made of over
400 separate eyes,
to
so placed as
allow of vision in
every direction at

the same time.
Such an organism
proves that it was
not by a series of
experiments, be-
ginning at the
least complex,
that the Creator
or-

formed the
ganic world; for

2

there is infinitely more complexity and delicacy
of design in a Trilobite's eye than in the gigantic
limb of an elephant or a mastodon.

The scenery of the Cambrian system is very

bold and bleak, its slaty strata being split into rugged peaks, whose precipitous sides render any attempt to gain their summits perfectly futile. MOLLUSCA (flabby or jelly-like) are divided The pass of Llanberis exemplifies this wild asinto five orders-viz., 1. CEPHALOPODS (head-pect most effectively, and fills the spectator with footed); examples-nautilus, cuttlefish, &c. 2. feelings of awe and admiration. The Cambrian GASTEROPODS (belly-footed); example black-system is rich in metals, supplying quantities of snail. 3. BRACHIOPODS (arm-footed). 4. CON- silver, iron, tin, and copoer ores, the getting of CHIFERA (shell-bearing). 5. ACEPHALA (headless); In the next chapter I shall enter upon the conwhich affords employment to hundreds of miners. example oyster. sideration of the Silurian system.

RADIATA are divided into three orders-viz., 1. BRYOZOA (sea-weed life). 2. ECHINODERMATA (spiny-skinned); example-star-fish, &c. 3. POLYPARIA; example-coral zoophyte.

(To be continued.)

MICROSCOPICAL JOTTINGS IN TOWN
AND COUNTRY.
No. V.

PROTOZOA (first life) are of a threefold order-viz., 1. FORAMINIFERA (having an aperture) so termed because the air-shell is divided into partitions, each of which is united with the succeeding one by a small aperture. 2. AMOR-HE foot of the fly will well repay our careful PHOZOA (mis-shapen life); example-sponge, &c. T study, for the foot proper, is distinguished

Lepidoptera. Wings mounted as ope Amongst common English species the F natus alexis and the peacock are, perhap most suitable. They should be laid nied slide with a shallow cell around them, F may be of card or thick paper, and covend a thin glass square or circle. Scales f wings are also very interesting as tras for moderately high power. From a kindly given me by a friend who can Howden, I have secured some ver dore scales that display their bead beautifully under a fin. or in. Fed these are very beautiful. Antenna alThe former are often very good, wa mounted in balsam, and also as Their respiratory system is simple study. Honey Bees and Wasps.leg and foot of the bee is most interes stings of both bee and wasp are easily and are worthy careful observation. nicely mounted dry is good. Cater interesting for their feet, their breaths or spiracles, and their respiratory tubers The creature may be dissected in waterr a small pair of scissors, and the org being carefully washed, may be mounted or in balsam. Amongst ertebrata large field, and we cannot now do m glance at a few of the more prominent a Prick our fingers and we get blood-al interesting object. From the cow we milk and see its oil globules. From the ep of any vertebrated animal we have hair to in balsam for polariscope or ordinary Hair, perhaps, requires more than a p note. Take human hair; mount it in t after a good cleansing and a soaking in t tine, and then subject it to a thorough nation with in. or in. Its structure is n this Externally there are the inn flattened cells that form the cortical laye next to this there is a peculiar fibrous substa forming the principal portion of the s diffused through which is the colouring where that is present: and lastly, in the centre of the hair, the medi stance or pith. So that our reades se that the hair-dresser's notion of the that it is a quill-is wide of the rat, and that a truer similitude would beat of a twig or rush.

:

From a joint of meat we may obtain muscular fibre of great interest under a high power-s at least, a good fin.-adipose or fatty tissue, bo for sectionizing, yellow and white cotter tissue, &c.

From fishes we can get scales. A piece skin in balsam affords a magnificent po object; and a fragment of sole-skin af equally splendid opaque object for los Scales may be mounted dry for ordinary nation, and in balsam for polariscope. the most beautiful for the latter are sole plaice.

Our readers will have noticed the ignored the existence of the vegetable! hitherto, although it has been in that that my work has hitherto been done. too late to touch upon the matter furth point out a few directions in which and amusement may be found, and tr chances of life to afford me future o touching upon them in detail.

Pollen. Easily obtained, and to be dry in a cell just deep enough-thatcomposite of mallows and passion for

3. INFUSORIA (existing in infusion) infinitely from the leg, is furnished with a most elaborate beautiful. The anthers may be mount minute animalcules, 40,000 of which would but arrangement for enabling the creature to ascend the pollen in situ for low power opaque. fill a cubic inch. vertical and polished surfaces, or even to walk-Sections mounted dry, and in fluid, or Having now described the classification of the with its body downwards in apparent opposition for ordinary light or polariscope. Le" animal world, I will again resume the description to the force of gravity. The arrangement by tions of), also hairs and scales-all very of the secondary formation. Pursuing my which this is brought about consists of a pair of ing and easy of collection and mounting. former method I shall commence with expansions with which each foot is furnished: Fronds in fructification as dry opaques. the Cambrian system, which lies immediately around the edges of these expansions, called a series of several dozens, and have not ye above the clay slate. It is principally composed pulvilli, are ranged rows of minute discs (only exhausted the store. Many of mine the of slates, schists, and limestones, and is met visible by the aid of a high power), which seem exotic. with mostly in Wales and the northern counties to act as "suckers." The foot must be mounted of England. At the period of the formation of in balsam. The rules laid down for the proboscis this system it is evident from the fossil remains will apply. that the temperature was far greater than that which prevails on any portion of the globe at the present time. Too torrid for terrestrial vegetation or animal organization, life was confined to the cooler habitation of the sea; it, however, swarmed with lowly organisms and plants whose remains we now find deep buried in their stony vaults.