of the conductor. The author has been led to these views by remarking the extreme rapidity with which an electrometer, connected by a fine wire with a conductor insulated above the roof of his temporary electric observatory in the island of Arran, became charged, reaching its full indication in a few seconds, and sometimes in a fraction of a second, after being touched by the hand, during a gale of wind and rain. The conductor, a vertical cylinder about 10 inches long and 4 inches diameter, with its upper end flat and corner slightly rounded off, stood only 8 feet above the roof, or, in all, 20 feet above the ground, and was nearly surrounded by buildings rising to a higher level. Even with so moderate an exposure as this, sparks were frequently produced between an insulated and an uninsulated piece of metal, which may have been about 'th of an inch apart, within the electrometer, and more than once a continuous line of fire was observed in the instrument during nearly a minute at a time, while rain was falling in torrents outside.

On Sir Christopher Wren's Cipher, containing Three Methods of finding the Longitude. By Sir D. BREWSTER.-Sir David said that at page 263 of his " Life of Sir Isaac Newton," the following paragraphs would be found:-" The bill which had been enacted for rewarding the discovery of the longitude seems to have stimulated the inventive powers of Sir Christopher Wren, then in his eighty-third year. He communicated the results of his study to the Royal Society, as indicated by the following curious document which I found among the manuscripts of Newton-Sir Christopher Wren's cipher, describing three instruments proper for discovering the longitude at sea, delivered to the Society November 30, 1714, by Mr Wren :

เ

OZVCVAYINIXDNCVOCWEDCNMALNABECIRTEWNGRAM

We presume that each of these paragraphs of letters is the description of a separate instrument. If it be true that every cipher can be deciphered, these mysterious paragraphs, which their author did not live to expound, may disclose something interesting to science." Sir David Brewster went on to say that soon after the publication of "The Life of Sir Isaac Newton," he had received a letter from Mr Francis Williams, of Grange Court, Chigwell, suggesting very modestly, that as the deciphering of the cipher, as published, was so simple, he supposed many persons had already done so; but if not, he begged to say that the mystery could be solved by reading the letters backwards in each of the three paragraphs, omitting every third letter. He had, on the approach of the Meeting of the British Association, received permission from Mr Williams to give an account to this Section of Mr Williams's method of solving the enigma. In his letter conveying the permission, which Sir David read, he suggests that " Sir Christopher Wren's object was to make it too mysterious to be of use to any one else. It is possible he may have wished to delay for a time the publication of his inventions, perhaps till he had improved his instruments, but was afraid that in the interval another would hit upon and publish the same discovery. He would send this cipher, then, to the Royal Society as a proof to be used at any future time." Sir David had the following explanation then, in accordance with Mr Williams's suggestion, written upon the black boards, the letters to be omitted being written in small characters to distinguish them, and backwards :

WACCHhMArGNwETrICeBAnLAm NCdEWcOUcNDxINiVAvCUz O.-Wach magnetic balance wound in vacuo (one letter a misprint). The omitted letters similarly read are-Chr. Wren, mdccxiv.

FIcXHhEArDHwIPrPÉeSHnANmDEdSPcOICSEXTUiBEiONIEYi EZ.-Fix head hippes handes poise tube on eye (one letter a misprint). Omitted letters make-Chr. Wren, mdccxiiii.

PICPEhSCrREwWErMOeV In NGmWHdEEcLScFRÃOMIBEvAKz E-Pipe screwe moving wheels from beake. Omitted letters make-Chr. Wren, mdccxiv.

The three last omitted z's occurring in the first part of each cipher to show that that part must be taken last.

On an Improvement in the Heliometer. By Mr N. POGSON.-The purpose of this communication is to suggest what I conceive to be a great addition to the power of any kind of micrometer used for measuring long distances on the double-image principle. It is therefore especially applicable to heliometers, and has indeed occurred to me chiefly from familiarity with the defects which have hitherto rendered this costly but magnificent instrument a comparative failure. It is well known to practical astronomers that the contact between two stars, however skilfully made, is a very unsatisfactory observation, even when the objects are pretty equal. But when one is a large bright star and the other a faint one, the difficulty and uncertainty amount to impossibility; for the faint star is invariably obliterated on approaching within two or three seconds of its superior. The alternative is then to diminish the aperture of that half of the object-glass through which the brighter star is viewed; but here again arises another evil; the disc is enlarged by diffraction, the value of the scale sensibly changed, and definition materially injured. Hence, parallax determinations of first magnitude stars, such as Arcturus and a Lyræ, cannot be satisfactorily made; but when the object is a double star, as, for instance, 61 Cygni or Castor, the comparison star can be brought between the components of the double star, and a most exquisitely perfect and comfortable measure obtained. Now, from having used the rock-crystal prism micrometer when residing at Oxford last year -then kindly lent me, together with a five-foot telescope of surpassing excellence, by Dr Lee-the idea occurred to me of introducing a prism, or achromatised wedge of rock crystal, into the heliometer, so as to double the image of the brighter star. By this means the dubious contact would be dispensed with; for the fainter object, by being brought midway between the two images of the bright star, would be precisely similar to the present easy observation of 61 Cygni, previously referred to. The prism could be of such a constant angle as to separate the two images to a convenient distance,-not too far, so as to render the estimation of distance difficult, but just wide enough to prevent the obliteration of a faint comparison star, before named as one of the evils to be avoided. The prism rather improves the appearance of a bright star than otherwise; and as the images are doubled, of course half the light of each is lost, equivalent to a considerable reduction of the aperture, thus obviating the third objection alluded to at starting. Armed with this addition to its strength, and taking the precaution never to observe on bad nights, when the atmosphere will not permit the use of powers from three hundred upwards -for I hold it as an absurdity to attempt to investigate tenths of a second of arc with anything less-the heliometer is doubtless yet destined to realise the highest expectations ever raised as to its efficiency for grappling with that most minutely intricate and vastly important research, viz., the parallax of the fixed stars.

On Chinese Astronomy. By Mr J. B. LINDSAY.-The object of the present paper is to draw the attention of the Section to the fact, that much

information may be derived from Chinese literature in order to perfect our astronomy. The "Chun-tsiu," written by Confucius, contains an account of thirty-six eclipses (several of them total), and several comets, falling stars, and meteorites. The first eclipse here recorded was in the year before our era 719, the last was in B.C. 494,-thus comprising 225 years. Confucius was born in B.c. 550, and died at the age of seventythree in B.C. 477. In a book lately published I have given an extract of the thirty-six eclipses; but the whole of the "Chun-tsiu "deserves to be translated and published. I have myself made a translation of the whole verbatim, but should prefer seeing it published by another better acquainted with the Chinese. The Chun-tsiu" is a short chronicle of events; but there is an extended commentary on it entitled the "Tsochuen," by Tso-kin-ming, who was a contemporary and an intimate friend of Confucius. This work should, I think, be also translated, as it gives a detailed account of astronomical observations, and comes thirteen years further down than the work of Confucius. Another work, entitled the "Kwo-yu," supposed to have been by the same author, contains an Appendix by another person, bringing down the history to B.c. 453. The succeeding history was principally written, and the celestial phenomena recorded, by Szi-ma-tsien, who lived a century before our era. His work is entitled "Shi-ki," or Historic Memoirs. He was Imperial Historian, as was also his father, and his work is extremely interesting, as giving an account not only of Chinese affairs, but also of the Scythians and Turks who were then on the north-west borders of China. The 123d chapter, recording foreign events, has been translated into French by Brosset, and is found in the Journal Asiatique for 1828. This chapter comprises the history of forty-three years, or from B.c. 140 to B.C. 97, shortly before the author's death. Small portions of the "Shi-ki " have been translated into English, but the whole deserves to be so. A translation of the whole Chinese history and literature before our era would not be voluminous; but the "Chun-tsiu," the "Tso-chuen," and the "Shi-ki" should, I think, be translated first. Extended notes would be necessary to render the whole intelligible, and the Astronomer Royal might append notes on the various eclipses. The ancient Chinese classics are nine in number,-five of the first class, and four of the second. The five of the first class are the "Shu-king," the "Shi-king," the "I-king," the "Li-ki," and the "Chun-tsiu." The "Shu-king" has been translated into French by Desguignes,-the "Shi-king" into Latin by Lacharme, the "I-king" into Latin by Regis, and others,-the "Li-ki" into French by Callery; but the " Chun-tsiu" has not yet been translated into any European language. The four books of the second class have been often translated into Latin and French. Their names are, the Ta-tteo," the "Chung-yung," the "Lun-yu," and "Mang-tszi," or Mencius, scarcely any of which have been translated into English.

66

On the Decomposed Glass found at Nineveh and other places. By Sir D. BREWSTER. He described the general appearance of glass in an extreme state of decomposition, when the decomposed part was so rotten as to break easily between the fingers, a piece of undecomposed glass being generally found in the middle of the plate. He then explained how, in other specimens, the decomposition took place around one, two, or more points, forming hemispherical cups, which exhibit the black cross and the tints of polarised light. In illustration of this decomposition, he showed to the Meeting three specimens, in one of which there was no colour, but which consisted of innumerable circular cavities with the black cross, these cavities giving it the appearance of ground-glass. In another specimen the film was specular and of great beauty, showing the complementary colours by reflection of transmitted light. In a third variety NEW SERIES.-VOL. XI. NO. I. JAN. 1860.

the films were filled with circular cavities exhibiting the most beautiful colours, both in common and polarised light.

On Mild Winters in the British Isles. By Professor HENNESSY.-He pointed out the circumstance that the meteorological observations made during the late remarkably mild winter tended to confirm the law which he had already announced in a letter to General Sabine, which appears in the Proceedings of the Royal Society for 1858. This law is, that during mild winters the coast stations exhibit an increase of temperature more than inland stations, and that the temperature on the west and south coasts approaches towards uniformity. In France, as pointed out by M. Liais, the first part of this law is found to hold good, as evinced in the comparative climatology of Cherbourg and Paris. Mr Hennessy referred these phenomena to an abnormal extension of heat-bearing currents across the Atlantic. From the greater stability of such currents than those of the atmosphere, and from the important influence they undoubtedly exercise upon our climate, he is led to infer that we are rapidly approaching a period when it may become possible to foretell whether the winter shall be cold or warm by knowing the conditions of temperature and the movements of currents in the Gulf of Mexico and the Atlantic during the summer and autumn.

On the Inclination of the Planetary Orbits. By Mr J. P. HENNESSY.— The author stated, that on consulting a synoptic table of the planetary elements, some law had been obtained for the other elements, but none hitherto for the inclinations of the several orbits. This he conceived arose from the inclinations being set down in reference to the plane of the earth's orbit; for he found that a very remarkable relation manifested itself when they were tabulated in reference to the plane of the Sun's equator. The author had written on the board two tables: one, the ordinary table in reference to the Ecliptic; the other, that to which he wished to draw attention, having reference to the plane of the Sun's equator. In the latter, it was seen as a general law, that the inclinations of the planetary orbits increased as the distances of the several planets from the Sun increased. Thus, the inclination of the orbit of Mercury to the plane of the Sun's equator was but 0° 19′ 51′′, while that of Neptune was 9° 6' 51". The only considerable deviation from regular progression being found, as might be expected, among the Asteroids: of which, if we take Victoria as a type, her inclination is no less than 15° 42′ 15′′. The author considered that the fact that the orbits of the larger planets, Jupiter, Saturn, Uranus, and Neptune, are not more inclined, would seem to confirm a surmise of Laplace, who, in his "Exposition du Systême du Monde," speculates on the order in which the planets were thrown off from the Sun, and supposes that Jupiter, Saturn, &c. were thus formed long before Mercury, Venus, the Earth, and Mars. If so, the oblateness of the Sun would in its condition at that time have tended more powerfully than in its subsequent or present state to keep the planets near the plane of its equator. The discovery of this law regulating the inclinations of the planetary orbits appeared to him another addition to the class of facts which establish the analogy between the solar system and that of Jupiter and his satellites, it being well known to astronomers that the inclination of the orbits of the latter to the plane of Jupiter's equator was a function of their distances and masses.

On the Dynamical Theory of Gases. By Professor CLERK MAXWELL.— The phenomena of the expansion of gases by heat, and their compression by pressure, have been explained by Joule, Claussens, Herapath, &c., by the theory of their particles being in a state of rapid motion, the velocity depending on the temperature. These particles must not only strike against the sides of the vessel, but against each other, and the calculation of their

motions is therefore complicated. The author has established the following results:-1. The velocities of the particles are not uniform, but vary so, that they deviate from the mean value by a law well known in the "method of least squares." 2. Two different sets of particles will distribute their velocity, so that their vires viva will be equal; and this leads to the chemical law, that the equivalents of gases are proportional to their specific gravities. 3. From Professor Stokes's experiments on friction in air, it appears that the distance travelled by a particle between consecutive collisions is about 1 of an inch, the mean velocity being about 1505 feet per second; and therefore each particle makes 8,077,200,000 collisions per second. 4. The laws of the diffusion of gases, as established by the Master of the Mint, are deduced from this theory, and the absolute rate of diffusion through an opening can be calculated. The author intends to apply his mathematical methods to the explanation on this hypothesis of the propagation of sound, and expects some light on the mysterious question of the absolute number of such particles in a given

mass.

CHEMICAL SCIENCE.

New Process of Preserving Milk perfectly Pure in the Natural State, without any Chemical Agent. By the Abbé MoIGNO. To preserve milk for an indefinite period is an important problem, which in France has been solved in three different modes. M. de Villeneuve was the first to preserve milk, solidifying it by the addition of certain solid ingredients, but it was no longer, properly speaking, milk. M. de Signac preserved it by evaporating the milk till it became of the consistence of syrup, rendering it a solid mixture of milk and sugar; still it could not be called milk. M. Maben also preserved it by excluding the air, and exposing it to an atmosphere of steam about 100° Cent.-thus depriving it of all the gases which it contained, and then hermetically sealing the filled bottles in which it had been heated. When about to leave for Aberdeen, I opened a bottle which had been closed by M. Maben on the 14th of February 1854; and after a lapse of five and a half years, I found it as fresh as it was the first day. M. de Pierre has greatly improved the discovery. The means which he employs to effect the preservation of milk is still heat, but heat applied in some peculiar way, by manual dexterity, first discovered by a Swiss shepherd. All that I am allowed to state is, that the effect of this new method of applying heat is to remove a sort of diustore, or animal ferment, which exists in milk in a very small quantity, and which is the real cause of its speedy decomposition. When this species of ferment is removed, milk can be preserved for an indefinite period of time in vessels not quite full, and consequently exposed to the contact of rarified air—a result which was not effected by the process of M. Maben, or rather that of M. Gay-Lussac, as they completely expelled those gases which otherwise would have rendered it sour. I have such full confidence in the success of M. de Pierre's process, that I had not the least hesitation in bringing along with me from Paris to Aberdeen a large vessel containing five gallons of milk, fearlessly trusting it to railroads and steam-boats, thus exposing it to all the incidents of the journey. I am so confident of the success of the process, that I pour out the contents of this large vessel into Scotch glasses, with the conviction that I am giving to the ladies and gentlemen of the British Association a milk as natural, as pure, and as rich as when it was taken from the cow in the fertile plains of Normandy. May this potion, so sweet and so pure, be a symbol of those sentiments of benevolent affection which France, flourishing and enlightened, entertains towards her noble and great sister England!