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the temperature of the room where the experiment is tried. The “ Parliamentary candle,” therefore, may be pronounced a failure wherever accurate results are required. The general principle on which the illuminating powers of different substances have hitherto been tested depends on the optical law that the amount of light which falls upon a given surface varies inversely with the square of the distance between the source of light and the object illuminated. In practice, however, this method is not sufficiently accurate to be used, except for the roughest approximations. The rest of Mr. Crookes' paper is devoted to details of a process he has invented to get rid of the “ Parliamentary candle.” This is, however, too abstruse and minute for extraction here.
The Earl of Rosse, F.R.S., has communicated a paper “On the Radiation of Heat from the Moon,” which is too mathematical for a popular notice. The general result, however, is to show conclusively that the moon's heat is capable of being detected with certainty by the thermopile; no inconsiderable quantity of heat reaching the earth by radiation from the moon. The points to be determined were:-1. The heat which, coming from the interior of the moon, does not vary with the phase. 2. That which falls from the sun on the moon's surface and is at once reflected regularly and irregularly. 3. That which, falling from the sun on the moon's surface, is afterwards radiated as a heat of low refrangibility.
Mr. Ellery, of the Observatory, Melbourne, in a letter to the President of the Royal Society, gives an interesting account of the safe arrival of the great telescope we noticed at some length last year, and of the means which have been already taken to set it up and to make it available for its intended use. He states it had, on the whole, travelled perfectly round the Cape, his words being that “the principal or more delicate portions of the instrument came out in good order ; the specula are still in their coats of varnish, and their surfaces appear to be in perfect good order. Some of the large castings and portions of the gearing had got rusted, but not to an injurious extent. The piers were completed on New Year's morning, and form a magnificent piece of masonry; the stone employed being the grey basalt so common here (called blue stone'), in blocks from one to three tons in weight each. The building we have finally decided on is built of stuccoed brick-work, eighty feet long by forty wide. Forty feet in length is taken up by the telescope-room, which is covered by a ridged roof of iron travelling on rails on the walls, and moving back on the other forty feet of the building, leaving the telescope in the open air. The back forty feet is covered by a fixed roof lower than the moveable one, and will contain a polishing and engine-room, a capacious library, and an office for the observer. The cost of piers, building, and roof will be 17001. The Government, with hard economy in all other directions, have acted very liberally about this work.”
Dr. Radcliffe, M.D., has contributed a very able paper, entitled “Researches in Animal Electricity,” containing a description of certain instruments now employed for the first time in researches of this kind, the chief subjects of inquiry being the electrical phenomena which belong to nerve and muscle in a state of rest; those which mark the passing of nerve and muscle from a state of rest into that of action; the motor phenomena ascribed to the action of the “inverse" and "direct” voltaic currents, and electrotonus. The instruments used were Sir W. Thomson's reflecting galvanometer, Latimer Clarke's potentiometer, and some new electrodes devised by the author. The last, which is an ingenious adaptation of the idea on which Wheatstone's bridge is based, is an extremely delicate instru.
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ment for the measurement of tension. The new electrodes are simply pieces of platinum wire, flattened and pointed at the free ends, and having these free ends freshly tipped with sculptor's clay at the time of an experiment. Living nerve and muscle supply currents to the galvanometer (the nerve current and the muscular current, so called) which are not supplied by dead nerve and muscle. These currents, when the tissues supplying them are fresh and at rest, show that the surface composed of the sides of the fibres, and the surface composed of the ends of the fibres, are in opposite electrical conditions, the former surface being positive, the latter negative. Nerve and muscle, and the animal tissues generally, oppose a very high resistance to the passage of a common voltaic current, so high, indeed, as to justify the inference that muscles and nerves may be looked upon as non-conductors rather than as conductors. Again, in considering the electrical phenomena which mark the passing of nerve and muscle from a state of rest into that of action, the more the evidence is considered the more it seems to justify the conclusion, that the passing of nerve and muscle from the one state to the other is marked by a discharge of electricity analogous to that of the torpedo. Again, when experiments are made as to the “ motor phenomena” ascribed to the action of the “inverse and direct voltaic currents," it seems probable that, ordinarily at least, the sheaths of the fibres are charged positively at their exterior, and negatively at their interior. The resistance of the animal tissues to electrical condition, it is assumed, is sufficient to keep the two opposite electricities apart-an assumption, be it remarked, which is not a little borne out by the fact that the resistance which the voltaic current encounters in the hind limbs of a frog, when its course is up one limb and down the other, is sufficient to keep the two limbs in opposite electrical conditions as regards discharge. The general conclusion seems to be that muscular relaxation is associated with a state of charge, and muscular contractions with a state of discharge. It would even seem as if all the evidence so far gave countenance to the conclusion that the state of charge may cause muscular relaxation by keeping the molecules of the muscle in a condition of mutual repulsion, and that the state of discharge may lead to muscular contraction by doing away with that state of electrical tension which prevents the molecules of the muscle from yielding to the attractive force inherent in their physical constitution, and which is ever striving to bring them together. The experiments on electrotonus, and the results deducible from them, are of too technical a character for popular statement.
From Mr. Robert H. Scott, the Director of the Meteorological Office, we have a paper of some note, “On the connexion between oppositely disposed Currents of Air and the Weather subsequently experienced in the British Islands.” In this paper he states that Mr. Meldrum at the Mauritius, and he himself in England, had had their attention directed to remarkable storms which appeared to be connected with the previous existence at the earth's surface of the two windcurrents, polar and equatorial, in close proximity to each other. This was specially noticeable in a gale of January 22, 1868, when the atmospherical conditions over these islands were very remarkable. Easterly winds were prevalent over the central and northern portions of this country, while in France there were strong westerly gales. The channels of the currents were so close to each other, that while at Yarmouth there was a strong easterly gale, there was a westerly gale at Portsmouth. The contrast exhibited by the two currents as regards temperature was very remarkable, and a dense fog was experienced in London. Barometrical readings were very low over the regions which separated the districts of the respective currents. Next day pressure rose very rapidly; and this was the precursor of an equally sudden diminution of the amount, and of the advent of the equatorial current which swept with great violence over these islands, producing a very serious southerly gale on the 24th of January.
Other able papers to which we can only now refer, briefly as possible, are—a notice by Professor Maskelyne, “On the Mineral Constituents of the Breitenbach Meteorite ;” by Professor Abel, “On the History of Explosive Agents ;” by Dr. Archibald Smith, “ On the Causes of the Loss of the iron-built sailing-ship ‘Glenorchy’;" by Mr. H. F. Blanford, “On the Origin of a Cyclone;" by H. C. Sorby, whose paper on precious stones we have already noticed with some detail, “ On Jargonium, a new elementary substance associated with Zirconium ;" by Dr. R. Norris, “On the Laws and Principles connected with the Aggregation of Bloodcorpuscles both within and without the Vessels;” “On some Experiments with the great Induction Coil at the Royal Polytechnic,” by J. H. Pepper ; “On the mechanical description of Curves,” by W. H. L. Russell; “On the Thermodynamic Theory of Waves of Finite Longitudinal Disturbance," by W.J. Macquorn Rankine, F.R.S. ; "On a Group of varieties of the Human Neck, Shoulder, and Chest, with their Transitional Forms and Homologies in the Mammalia,” by John Wood, Esq., F.R.C.S., Examiner in Anatomy to the University of London ; “On the Cavern of Bruniquel and its Organic Contents,” by Professor Owen; "On a Comparison of the Granites of Cornwall and Devonshire with those of Leinster and Munster," by Professor Haughton; and “On Luteine and the Spectra of yellow Organic Substances,” by Dr. Thudicum.
One notice we must add here—though of a book rather than of a paper-by that veteran philosopher and man of science, Professor John Phillips of Oxford, who has recently made public an excellent account of “ Vesuvius,” and of his ascent of that mountain. Need we say that we hail this ascent (more than once) of Vesuvius during its recent outbreak by the Professor of Geology at Oxford with somewhat of the same feeling the scientific men of his day must have hailed that of the elder Pliny? only we rejoice where they deplored: our man of science comes back to us unburnt, we believe we may say, unscathed, while the great Roman naturalist remains under the volcanic storm which overwhelmed Pompeii and Herculaneum, and has not, we feel grateful to say, been as yet exhumeda spectacle for the gaping idiots of fashion who yearly “do” those interesting remains in their own meaningless and unprofitable method. Professor Phillips's work may be termed a history, not a merely scientific essay, for he tells us all the chief facts about the mountain from the time of Pliny to that of the eruption which, commencing in 1861, on December 8, is not even now entirely subdued. His style is at once clear and picturesque, and the following description of his view of the eruption from Naples affords a fair example of it:“One long burning stream," he says, “ flowed down the whole north-western slope of the great cone, quite reaching into and spreading across the Atrio del Cavallo. On the top, fitful bursts of clouds of fiery bombs and wide-spread ashesbelow, just where it appeared last night, but now far brighter, and glowing with a full steady eye of light, the second great burst of light and motion. Now it spreads its bright cloud above, then down to the valley ; knots and lines, sometimes double, of sharp white or reddish fire swelling into considerable masses, or broken into many gleaming points. Towards the base, a wild cataract of fire is pouring towards us, and is stretching its red fingers over the elder lava. Now and then a star-like point in advance seems to beckon onward 'der freien Tochter der Natur.' Finally, on the deepest part of the whole visible horizon, ahorizontal row of fourteen small bright star or gem-like fires marks the conquest of the current over the flat space of the Atrio, and seems to unite again the longseparated masses of Somma and Vesuvius-parent and child—the far-descended progeny of the struggling Titans.”
The British Association for the Advancement of Science met this year at Exeter under the distinguished Presidency of the Rev. G. G. Stokes, Lucasian Professor of Mathematics at Cambridge, and formerly Senior Wrangler. Professor Stokes delivered to the assembled members and their friends an address widely differing from some which the Association has heard in recent years, to some of the leading points of which we shall now briefly refer. Taking first, as was but natural for one of the most eminent of modern mathematicians, the great subject of Astronomy, Professor Stokes showed that, though Newton's discovery of the law of gravitation did practically explain almost all the motions of the heavenly bodies, yet it was fortunate for science that Adams at Cambridge, and Le Verrier in France, were able to reverse the problem; and, instead of determining the disturbing effect of a known planet, to set themselves to inquire what must be the mass and the orbit of an unknown body which shall be capable of producing by its disturbing force the unexplained deviations from the calculated place of Uranus. Passing on from this, Professor Stokes pointed out in how important a degree astronomy was indebted to the science of optics ; at the same time showing that astronomy well repaid this debt, by settling once and for ever the numerical powers of the velocity with which light travels, and, at the same time, exhibiting the remarkable phenomenon discovered by Bradley, and termed by him, and since his day, “ the aberration of light.” For optics, it may be urged that, though the motions of the heavenly bodies are chiefly revealed to us by astronomical observations, yet that the application of the spectroscope has proved to us the existence in them of various elements already known to us by the chemical examination of the materials of our own earth. It is clear, therefore, that the two sciences of optics and astronomy must be studied together, as the one throws the greatest light upon the other. Again, the science of optics has the highest value when we want to ascertain whether a particular star is approaching us or receding from us, and the chain of reasoning pursued is similar to what happens in the case of the pulsation of a musical note. The pitch of a note is well known to depend on the number of vibrations which reach the ear in a given time-say a second-so if light be, as we have good reason to believe, a vibrating fluid, the pulsations of this fluid may be reduced to calculation. Now the result of present scientific researches tends to prove that light consists of a tremor or vibrating movement propagated in an elastic medium filling the planetary and stellar places, a medium which thus fulfils for light an office similar to that of air for sound. The professor then went on to describe the value of Professor Kirchkoff's experiments on the lines in the solar spectrum, and demonstrated that though the coincidence of certain dark lines in the solar spectrum with bright lines in certain artificial sources of light had been in one or two instances previously noticed, still it was to Kirchkoff we owe the inference that a glowing medium which emits bright light of any particular refrangibility necessarily (at that temperature at least) acts as an absorbing medium extinguishing light of the same refrangibility. It is curious that in this discovery Kirchkoff was preceded, though unconsciously, by our own countryman Professor Balfour Stewart.
Naturally, therefore, on the occurrence of the famous total eclipse of the sun, which we fully noticed in our report of last year, the attention of astronomers was directed especially to the coloured protuberances on the sun's surface, not without the hope that the recent discoveries of the spectroscope might be found capable of explaining some of them. A telegram from a Danish astronomer, M. Janssen, was, we believe, the first to announce to the President of the Royal Society that the spectrum of these prominences did show bright lines, while that of the Corona showed none, the necessary conclusion being that these prominences were not clouds, but incandescent matter in a gaseous form. One of the most extraordinary results of these solar observations is the wonderful changes they bring to light; thus, prominences whose heights must be measured by tens and thousands of miles appear and disappear in the course of a few minutes.
Proceeding onwards, Professor Stokes called the attention of the meeting to the great progress which had been made in the manufacture and use of guncotton, together with a full description of some other of the most recent and most interesting chemical discoveries, such as the finding 6 per cent. of copper in the colouring of the wings of the turaco or plaintain-eater of the Cape ; an artificial substitute for madder ; a new opium base; some notices of the honours proposed to be shown to Faraday's memory; and the remembrance of the year 1869, as the centenary of that in which James Watt took out his patent for the invention of separate condensation, which many regard justly as the real birth of the steam-engine.
In conclusion, Professor Stokes grappled boldly, we are happy to say, with one of what are called the “problems of the day," and in the following noble words enounces the true creed of a philosopher and a Christian :-“ But do the laws of chemical affinity," says he, “to which, as I have endeavoured to infer, living beings, whether vegetable or animal, are in absolute subjection, together with those of capillary attraction, of diffusion, and so forth, account for the formation of an organic structure, as distinguished from the elaboration of the chemical substances of which it is composed! No more, it seems to me, than the laws of motion account for the union of oxygen and hydrogen to form water, though the ponderable matter so uniting is subject to the laws of motion during the act of union just as well before as after. In the various processes of crystallization, of precipitation, and so forth, which we witness in dead matter, I cannot see the faintest shadow of an approach to the formation of an organic structure, still less to the wonderful series of changes which are concerned in the growth and perpetuation of even the lowliest plant. Admitting to the full as highly probable, though not completely demonstrated, the applicability to living beings of the laws which have been ascertained with reference to dead matter, I feel constrained, at the same time, to admit the existence of a mysterious something lying beyond ; a something sui generis, which I regard not as balancing and suspending the ordinary means, but as working with them, and through them, to the attainment of a designed end. What this something that we may call life may be, is a profound mystery. We know not how many links in the chain of secondary causation may yet remain behind; we know not how few. It would be presumptuous, indeed, to assume in any case that we had already reached the last link, and to charge with irreverence a fellow-worker who attempted to push his investigation yet one step farther back. On the other hand, if a thick darkness enshrouds all beyond, we have no right to assume it to be impossible that