two contrary attractions, was 11.6 seconds. Hence, then, it is to be inferred, that the attraction of the earth is actually to the sum of the attractions of the hill nearly as radius to the tangent of 11.6 seconds, that is, as 1 to .000056239, or as 17781 to 1; or as 17804 to 1 nearly, after allowing for the centrifugal force arising from the rotation of the earth about its axis.

Having now obtained the two results, namely, that which arises from the actual observations, and that belonging to the computation, on the supposition of an equal density in the two bodies, the two proportions compared must give the ratio of their densities, which is that of 17804 to 9933, or 1434 to 800 nearly, or almost as 9 to 5. And so much does the mean density of the earth exceed that of the hill.

It appears not unreasonable to suppose the mean specific gravity of the mountain to be from 2.7 to 2.75 or 23. Now 2 x 23 gives 28, or almost 5; that is, under these circumstances, the medium density or specific gravity of the whole mass of the earth, in proportion to that of water, is nearly as 5 to 1, or that it is 5 times the weight of water.

Knowing, then, the mean density of the earth in comparison with water, and the densities of all the planets relatively to the earth, we can now assign the proportions of the densities of them all as compared to water, after the manner of a common table of specific gravities. And the numbers expressing their relative densities, in respect of water, are annexed.

Account of an Infant Musician. By CHARLES Burney, Doctor of Music and F. R.S.—[1779.]

WM. CROTCH was born at Norwich, July 5. 1775. His father, by trade, a carpenter, having a passion for music, of which, however, he had no knowledge, undertook to build an organ, on which, as soon as it would speak, he learned to play two or three common tunes, with which, and such chords as were pleasing to his ear, he used to try the perfection of his instrument. About Christmas, 1776, when the child was only a year and a half old, he discovered a great inclination for music, by leaving even his food to attend to it when the organ was playing; and about Midsummer, 1777, he would

touch the key-note of his particular favourite tunes, in order to persuade his father to play them. Soon after this, as he was unable to name these tunes, he would play the two or three first notes of them, when he thought the key-note did not sufficiently explain which he wished to have played.

Being left, while his mother went out, in the dining-room with his brother, a youth of about 14 years old, he would not let him rest till he blew the bellows of the organ, while he sat on his knee and beat down the keys, at first promiscuously; but presently, with one hand, he played enough of "God save the King" to awaken the curiosity of his father, who being in a garret, which was his work-shop, hastened down stairs to inform himself who was playing this tune on the organ. When he found it was the child, he could hardly believe what he heard and saw. At this time he was exactly two years

and three weeks old.

The next day he made himself master of the treble of the second part; and the day after he attempted the base, which he performed nearly correct in every particular, except the note immediately before the close, which, being an octave below the preceding sound, was out of the reach of his little hand. In the beginning of November, 1777, he played both the treble and base of "Let ambition fire thy mind,” an old tune, which is, perhaps, now better known by the words to which it is sung in "Love in a Village," " Hope, thou nurse of young desire."

At this time, such was the rapid progress he had made in judging of the agreement of sounds, that he played the Easter hymn with full harmony; and in the last two or three bars of Hallelujah, where the same sound is sustained, he played chords with both hands, by which the parts were multiplied to six, which he had great difficulty in reaching on account of the shortness of his fingers. It was, also, to be observed, that in making a base to tunes which he had recently caught by his ear, whenever the harmony displeased him, he would continue the treble note till he had formed a better accompaniment.

Another wonderful part of his prematurity was the being able, at two years and four months old, to transpose into the most extraneous and difficult keys whatever he played; and now, in his extemporaneous flights, he modulates into all keys with equal facility. The last qualification which Dr. B. points out as extraordinary in this infant musician, is the being able to play an extemporary base to easy melodies, when performed by another person on the same instrument.

But these bases must not be imagined correct, according to the rules of counter-point, any more than his voluntaries. He generally gives, indeed, the key-note to passages formed from its common chord and its inversions, and is quick at discovering when the fifth of the key will serve as a base. At other times he makes the third of the key serve as an accompaniment to melodies, formed from the harmony of the chord to the key-note; and if simple passages are played slow, in a regular progression, ascending or descending, he scon finds out that thirds or tenths, below the treble will serve his purpose in furnishing an agreeable accompaniment.

Musical prodigies of this kind are not unfrequent: there have been several in Dr. B.'s memory on the harpsichord. But the two sons of the Rev. Mr. Wesley seem to have discovered, during early infancy, very uncommon faculties for the practice of music. Charles, the eldest, at 23 years old, surprised his father by playing a tune on the harpsichord readily, and in just time: soon after he played several, whatever his mother sung, or whatever he heard in the street. Samuel, the youngest, though he was three years old before he aimed at a tune, yet by constantly hearing his brother practise, and being accustomed to good music and masterly execution, before he was six years old arrived at such knowledge in music, that his extemporary performance on keyed instruments, like Mozart's, was so masterly in point of invention, modulation, and accuracy of execution, as to surpass, in many particulars, the attainments of most professors at any period of their lives. Indeed Mozart, when little more than four years old, is said to have been "not only capable of executing lessons on his favourite instrument, the harpsichord, but to have composed some in an easy style and taste, which were much approved;" and Samuel Wesley, before he could write, was a composer, and mentally set the airs of several oratorios, which he retained in memory till he was eight years old, and then wrote them down.

On the Eruption of Mount Vesuvius, in August, 1779. In a Letter from Sir WM. HAMILTON, K.B. F.R.S. On the 5th of August, about two o'clock in the afternoon, Sir W. perceived, from his villa at Pausilippo, in the bay of Naples, whence he had a full view of Vesuvius, which is just opposite, and at the distance of about six miles in a direct line from it, that the volcano was in a most violent agitation : white and sulphureous smoke issued continually and impe

tuously from its crater, one puff impelling another, and by an accumulation of those, clouds of smoke resembling bales of the whitest cotton. Such a mass of them was soon piled over the top of the volcano, as exceeded the height and size of the mountain itself at least four times. In the midst of this very white smoke, an immense quantity of stones, scoriæ, and ashes, were shot up to a wonderful height, certainly not less than 2000 feet.

August 7. the volcano remained much in the same state; but about midnight its fermentation increased greatly. The second fever-fit of the mountain may be said to have manifested itself at this time. Sir W. was watching its motions from the mole of Naples, which has a full view of the volcano, and had been witness to several glorious picturesque effects produced by the reflection of the deep red fire, which issued from the crater of Vesuvius, and mounted up in the midst of the huge clouds, when a summer storm, called here a tropea, came on suddenly, and blended its heavy watery clouds with the sulphureous and mineral ones, which were already like so many other mountains piled over the summit of the volcano at this moment a fountain of fire was shot up to an incredible height, casting so bright a light, that the smallest objects could be clearly distinguished at any place within six miles or more of Vesuvius.

August 8. Vesuvius was quiet till towards six o'clock in the evening, when a great smoke began to gather again over its crater, and about an hour after, a rumbling subterraneous noise was heard in the neighbourhood of the volcano: the usual throws of red-hot stones and scoriæ began, and increased every instant. At about nine o'clock there was a loud report, which shook the houses at Portici and its neighbourhood, to such a degree as to alarm their inhabitants, and drive them out into the streets; and many windows were broken, and walls cracked, by the concussion of the air from that explosion, though faintly heard at Naples. In an instant a fountain of liquid transparent fire began to rise, and, gradually increasing, arrived at so amazing a height as to strike every beholder with the most awful astonishment. The height of this stupendous column of fire could not be less than three times that of Vesuvius itself, which rises perpendicularly near 3700 feet above the level of the sea.

August 9. about nine o'clock in the morning, the fourth fever-fit of the mountain began to manifest itself by the usual symptoms, such as a subterraneous boiling noise, violent explosions of inflamed matter from the crater of the volcano,

accompanied with smoke and ashes, which symptoms increased every instant. The smoke was of two sorts; the one as white as snow, the other as black as jet. The white, as described in the former part of this journal, rolled gently mass over mass, resembling bales of the whitest cotton; and the black, composed of scoriæ and minute ashes, shot up with force in the midst of the white smoke, which, from the minerals, was also sometimes tinged with yellow, blue, and green. Presently such a tremendous mass of these accumulated clouds stood over Vesuvius as seemed to threaten Naples again, and actually made the mountain itself appear a mole-hill. This day's eruption was similar to that of the 5th, but many degrees more violent.

August 11. about six in the morning, the fifth and last fever-fit of the mountain came on, and gradually increased. About 12 o'clock it was at its height, and very violent indeed, the explosions being louder than those that attended the former eruptions. The same mountains of white cotton-like clouds, pilled one over another, rose to such an extraordinary height, and formed such a colossal mass over Vesuvius, as cannot possibly be described, or scarcely imagined. It may have been from a scene of this kind that the ancient poets took their ideas of the giants waging war with Jupiter.

Proceeding to Ottaiano, which is reckoned to contain 12,000 inhabitants, nothing could be more dismal than the sight of this town, unroofed, half buried under black scoriæ and ashes, all the windows towards the mountain broken, and some of the houses themselves burnt, the streets choked up with these ashes; in some that were narrow, the stratum was not less than four feet thick, and a few of the inhabitants just returned were employed in clearing them away, and piling up the ashes in hillocks to get at their ruined houses. The mountain of Somma, at the foot of which Ottaiano is situated, hides Vesuvius from its sight, so that till the eruption became considerable it was not visible to them. On the 8th, when the noise increased, and the fire began to appear above the mountain of Somma, many of the inhabitants of this town flew to the churches, and others were preparing to quit the town, when a sudden violent report was heard; soon after which they found themselves involved in a thick cloud of smoke and minute ashes: a horrid clashing noise was heard in the air, and presently fell a deluge of stones and large scoriæ, some of which scoria were of the diameter of seven or eight feet, and must have weighed more than 100 pounds before they were broken by their fall, as some of the fragments of them still