dited. It was imagined that the statement in the telegrams, that 7000 persons had perished in the town of Mendoza, was an exaggeration; but subsequent accounts showed that the extent of the calamity at that point had not been overstated. It would appear that this earthquake was inferior in violence to none recorded in history. The private letters state that "the city of Mendoza is no more;" and the number of persons who have perished there is variously computed at from 6000 to 7000. The loss of life was probably rendered the greater by the circumstance that the earthquake was preceded by a remarkable storm and by a hot rain, which drove the inhabitants into their dwellings for shelter. The greater part of San Juan has been destroyed, and 3000 persons are reported to have been killed. San Juan is situated 120 leagues to the north of Mendoza, at the foot of the Andes. The shock was felt with such severity at Cordova, 150 leagues from Mendoza, that the church was thrown down. It was also felt on the same day (March 20) and hour, but without any serious effects, at Buenos Ayres.

Mr. C. Murray, in a communication to the Geological Society, thus enumerates the localities visited by the earthquake :

At about to 9 o'clock the first shock, preceded by a thunder-clap, destroyed the city of Mendoza, killing (it is said) two-thirds of its 16,000 inhabitants. Altogether there were eighty-five shocks in ten days. The land-wave appears to have come from the south-east. Several towns S.E. of Buenos Ayres felt slight shocks. No earthquake took place in Chile; but travellers crossing the Upsallata Pass of the Cordilleras met with a shower of ashes; the pass was obstructed by broken rocks, and chasms opened on all sides. At Buenos Ayres, 323 leagues from Mendoza, and elsewhere, it was observed in watchmakers' shops that the pendulums moving N. and S. were accelerated; those moving E. and W. were not affected.

NOTES ON EARTHQUAKES AND EXTRAORDINARY AGITATIONS

OF THE SEA.

MR. R. EDMONDS has read to the Royal Institution of Cornwall the following Notes:

I stated many years since that Extraordinary Agitations of the Sea and of inland lakes are probably produced by vertical Earthquakeshocks acting on the waters perpendicularly to the plane or surface of the ground on which they rest. The effect of such a shock in the bed of a canal would be not only to drive the water from its sides towards the centre, where it would rise into a long ridge, but also to drive the water from its higher towards its lower end. In this latter case the water, when its momentum ceased, would flow back to the higher end, where, rising probably to a higher level than it had before, it would dam back any stream gently entering there. All this was exemplified in the Surrey Canal on the day of the great earthquake of Lisbon. That canal was seven hundred feet long and fifty-eight broad. "The water at its higher end usually deepens from two to four feet, growing gradually deeper to the west end, where it deepens to about ten feet." At and near the higher (eastern) end the ridge of water raised in the centre was about ninety

&

feet long, and between two and three feet above the usual level. This ridge heeled northward, and flowed over the walk on the north side of the canal; on the water s returning into the canal, another such ridge was raised in the middle which heeled southward, and flowed over the walk on the south side. During this second oscillation, the small stream at the higher end, which constantly flowed through the canal, was driven back thirty-six feet towards its source. This was considered as the effect of the second oscillation; but no oscillation from side to side could have increased the depth at the higher end where the stream entered. It was probably the second oscillation from end to end that dammed back the stream, for it must then have reached the higher end of the canal, and deepened the water there. The oscillations from end to end no doubt escaped observation on account of the tenfold more striking oscillations from side to side.

Every extraordinary agitation of the sea (unaccompanied with a known earthquake-shock) that I have read of, where the state of the weather is mentioned, has occurred during a thunder-storm, or at or near a minimum, of the barometer; whereas earthquakes appear to take place equally in all states of the atmosphere. It is therefore important to ascertain why such earthquakes as are known only by the extraordinary agitation of the sea which they produce should occur exclusively during storms, or at or near minima of the barometer. Is it because submarine shocks are always vertical, while those on dry land are generally horizontal? In vertical shocks there may be electrical discharges between the earth and the atmosphere which might occasion the attendant minima, as in the case observed by Humboldt, where "the mercury was precisely at its minimum height at the moment of the third and last shock," whilst in horizontal shocks the discharges may be only between differently charged portions of the earth without much affecting the atmosphere.

Mr. Mallet, in his first report on earthquakes, asks whether the reason why ducks in ponds often rush suddenly from the water immediately before an earthquake may not be, "that with their heads immersed they are able to hear the first distant mutterings while yet inaudible through the air?" But how can this be when sounds do not travel through the earth faster than shocks? It is true that earthquake sounds are often heard immediately before shocks are felt but such sounds must have been produced, not by the vibrations which were afterwards felt, but by preceding vibrations which were not felt at all. The numberless rapid vibrations constituting a shock vary considerably in power, so that the weaker ones if they came first and reached no higher than the bottom of the pond, might have alarmed the birds before the stronger ones were felt on its banks. That shocks may reach ponds without being perceived by persons close by them was abundantly proved during the great earthquake of Lisbon.

Humboldt, at Cumana, felt an earthquake during a thunder-storm at the moment of the strongest electrical explosion; on the following * Philosophical Transactions, vol. xlix. p. 354.

R

day at the same hour was a violent gust of wind with thunder, but no shock; the wind and storm returned for five or six days at the same hour, almost at the same minute: and he states that such diurnal periodicities have been often observed at Cumana, and by M. Arago and himself at Paris. I have observed periodicities equally striking, although the intervals, instead of being days, are lunations (29 days each) or multiples of a lunation, and generally at the moon's first quarter. As these, as well as those observed by Humboldt, resulted probably from changes in the magnetic or electric state of the earth or atmosphere, which is periodically varying not only each day, but also according to the positions of the sun and moon in respect of the earth, it seems probable that at the end of each lunation, when the circuit is completed, and the sun, moon, and earth have returned to nearly the same relative positions as they had at the beginning, the magnetic or electric states of the earth and atmosphere, and the weather consequent thereon, would also be nearly the same at the end as at the beginning, subject only to such modifications as other intervening influences would occasion. These intervening influences are no doubt so considerable as to render it difficult to determine whether the examples referred to are merely accidental, or whether they depend in some measure on the relative positions of the sun, moon, and earth, and the locality of the observer. The very numerous examples, however, of lunar periodicities which I have given in the British Association Report for 1850 (Séctions), p. 32, cannot, I think, be merely accidental. These are exclusively remarkable maxima of the therinometer. Other tables of remarkable lunar periodicities I have given in the British Associa tion Report for 1845 and elsewhere, consisting sometimes of maxima and sometimes of minima, and sometimes of the barometer and soinetimes of the thermometer, and it might therefore be objected that the proof of lunar influences would have been more satisfactory had the examples been all maxima or all minima of the same instrument. But it must be borne in mind that the weather being at all times dependent on the ever-changing electric or magnetic state of the atmosphere, must be very different in most respects immediately after a discharge (visible or invisible) of its electricity or magnetism from what it was immediately before; and a considerable maximum one day might be followed by a considerable minimum the next. Some have concluded that the moon has no sensible influence on the weather, because the means of the observations of the barometer or other instruments on the days of new and full moon, and of the quarters respectively, show no difference between any one of these four days and any other. But this proves nothing, as the change expected rarely occurs at the precise day owing to other influences retarding or accelerating it.

Others deny any such influence of the moon, because it is not apparent in the averages of the readings of each respective day of the new and full moon, and quarter days conjoined with the two days before and the two days after it. But should any remarkable change occur, it could not be detected by such averages, as the

maximum or minimum in the former part of these five days would be often neutralized by an opposite state of the instrument in the latter part.

The only way, therefore, of ascertaining whether the moon's first quarter is or is not most remarkable for excessive meteorological changes, is to refer each excessive or remarkable state of the atmosphere to such of the moon's four quarter-days as may be nearest, and then to compare the results.

THE IMPERIAL CROWN OF ENGLAND.

[As incorrect descriptions have, from time to time, appeared of the Imperial Crown, the following corrected details, by Mr.J. Tennant, Professor of Geology and Mineralogy, King's College, London, will be acceptable to the reader. His account is appended to the reprint of Mr. W. Pole's paper on Diamonds.]

The Imperial State Crown of Her Majesty Queen Victoria was made by Messrs. Rundell and Bridge in the year 1838, with jewels taken from old crowns and others furnished by command of Her Majesty. It consists of diamonds, pearls, rubies, sapphires, and emeralds, set in silver and gold; it has a crimson velvet cap, with ermine border, and is lined with white silk. Its gross weight is 39oz. 5dwts. troy. The lower part of the band, above the ermine border, consists of a row of 129 pearls, and the upper part of the band a row of 112 pearls, between which, in front of the crown, is a large sapphire (partly drilled) purchased for the crown by His Majesty King George IV. At the back is a sapphire of smaller size, and six other sapphires (three on each side), between which are eight emeralds. Above and below the seven sapphires are 14 diamonds, and around the eight emeralds 128 diamonds. Between the emeralds and sapphires are 16 trefoil ornaments, containing 160 diamonds. Above the band are eight sapphires surmounted by eight diamonds, between which are eight festoons consisting of 148 diamonds. In the front of the crown, and in the centre of a diamond Maltese cross, is the famous ruby said to have been given to Edward Prince of Wales, son of Edward III., called the Black Prince, by Don Pedro, King of Castile, after the battle of Najera, near Vittoria, A.D. 1367. This ruby was worn in the helmet of Henry V. at the battle of Agincourt, A.D. 1415. It is pierced quite through after the Eastern custom, the upper part of the piercing being filled up by a small ruby. Around this ruby, to form the cross, are 75 brilliant diamonds. Three other Maltese crosses, forming the two sides and back of the crown, have emerald centres, and contain respectively 132, 124, and 130 brilliant diamonds. Between the four Maltese crosses are four ornaments in the form of the French fleur-de-lis, with four rubies in the centres, and surrounded by rose diamonds, containing respectively 85, 86, 86, and 87 rose diamonds. From the Maltese crosses issue four Imperial arches composed of oak leaves and acorns, the leaves containing 728 rose, table, and brilliant diamonds, 22 pearls forming the acorns, set in cups containing 54 rose diamonds and one table diamond. The total number of diamonds in the arches and acorns is 108 brilliants, 116 table, and 559 rose diamonds. From the upper part of the arches are suspended four large pendant pear-shaped pearls, with rose diamond caps, containing 12 rose diamonds, and stems containing 24 very small rose diamonds. Above the arch stands the mound, containing in the lower hemisphere 304 brilliants, and in the upper 244 brilliants: the zone and are being composed of 33 rose diamonds. The cross on the summit has a rose-cut sapphire in the centre, surrounded by four large brilliants, and 108 smaller brilliants. Summary of jewels comprised in the crown :-1 large ruby irregularly polished, 1 large broad-spread sapphire, 16 sapphires, 11 emeralds, 4 rubies, 1363 brilliant diamonds, 1273 rose diamonds, 147 table diamonds, 4 drop-shaped pearls, 273 pearls.

260

Astronomical and Meteorological Phenomena.

REPORT OF THE ASTRONOMEK-ROYAL FOR 1860-61.

THE Report of the Astronomer-Royal to the Board of Visitors of the Royal Observatory, Greenwich, exhibits generally the state of the Observatory on May 10, 1861, and the proceedings in the Observatory from May 20, 1860, to that date. The AstronomerRoyal expects that in a short time a considerable extension of the buildings of the Observatory will be found necessary. It is supposed that there will be difficulty in finding the requisite space on the Observatory Hill, and there are very strong objections against. the abandonment of the present site. On May 7, the Observatory obtained possession of Dr. Bradley's observations, which had been carried off after his decease, and found their way into the University of Oxford in 1776; thus preventing access, at the most critical epoch in the history of astronomy, to the only observations on which reliance could be placed, and retarding the progress of accurate astronomy by nearly forty years. It is gratifying to learn that this great gap in the manuscript observations of the Observatory is at length filled up. The astronomical instruments are reported to be in good condition. The external galvanic communications with the telegraphic stations at London-bridge, and with the Admiralty wires, and the Magnetic and Submarine Company's wires at Deptford, are reported to be in the best possible order. The fundamental meridional observations are still considered as their peculiar and sacred charge. The stars observed are principally the following:192 clock stars; stars generally to the 5th magnitude; new circumpolar stars; moon conculminating stars; stars supposed to have a large proper motion, and variable stars; stars near Sirius; low stars for refraction; stars observed with Mars at opposition; and stars used in defining the Oregon boundary. The moveable bodies observed on the meridian are:-The moon at every opportunity; the sun and inferior planets on every day except Sundays; the superior planets when they pass before 15 h. solar time, and the large ones when they pass with the moon after 15 h. There has been a diminution this year of the number of meridional observations of all objects, and of altazimuthal observations, arising entirely from the excessive badness of the weather in the summer and autumn of 1860, and spring of 1861. Regarding the meteorological and magnetical department, we are informed that all the instruments are in good order. After several trials, a Robinson's anemometer has been established as a part of their permanent apparatus. It has been found much superior to Whewell's anemometer, proving the accuracy of the inventor's theory. Magnetical and meteorological observations, partially reduced, are now sent every day to M. Le