M. de Humboldt stated that he had established at Berlin, at the bottom of the mines of Freyberg in Saxony, at St. Petersburgh, at Casan, at Archangel, at Irkutsk, on the borders of Lake Baikal in Siberia, and at Pekin, magnetic houses in imitation of the magnetic observatory established at Paris in one of the apartments of the Observatoire Royal.

Ever since the reign of Peter the Great, the Russian Government has maintained a mission at Pekin, which is renewed every ten years; but there had never been any men of science attached to this mission until M. Fuss, the brother of the Secretary of the Academy of Sciences of St. Petersburgh, made a voyage to China last year, and commenced a series of meteorological, magnetic, and astronomical observations, which will be continued by M. Kowanko, a young officer of the mines, who is to pass ten years at Pekin. M. Fuss, on the 22d April last, wrote a letter from that city, which has been communicated by M. Kuppfer to M.

Arago and M. de Humboldt, and of which the following is the substance:

— M.

Fuss made magnetic observations in 17 stations during his progress through the celestial empire to Pekin; but he was afraid to take any astronomical measures, on account of the jealousy of the Chinese.

A tower in masonry has been constructed at Pekin, surmounted by a tent, as a protection against the inclemency of the atmosphere.

This observatory is surrounded by houses; but, happily for magnetic experiments, no iron is used in the Chinese buildings.

The cross on the top of the edifice, belonging to the Russian Mission, which is only a short distance off, serves as a point de mïre for the azimuthal directions.

On the 30th December, 1830, the magnetic inclination was found to be 54° 32′; and the declination observed on the 10th January, 1831, at three o’clock in the afternoon, was 1° 42′ 57″ West.

The longitude of the observatory is about 114° East of Paris; the latitude has been ascertained with precision to be 39° 54′ 9″. 5. This observation differs only by 5′ from that made by Father Hyacinth.

The magnetic observations are made at the same hour as in the European observatories above-mentioned.

Barometrical and thermometrical notes are taken four times every day.

From the winter solstice to the date of the letter, the maximum height of the barometer was 345.7 lines of Paris; this was at midnight, on the 10th of March, at which time a slight shock of an earthquake was felt towards the North; —the minimum was 330.9 lines, difference 14.8 lines.

The highest temperature during the same period was 25° centigrade, at four o’clock in the afternoon of the 20th April; and the lowest, 13°.5 below zero, at six in the morning of the 5th February: the mean temperature was 12°.

M. Kuppfer, in forwarding the above letter, announced that he had also recently received a letter from the celebrated Norwegian natural philosopher M. Hansteen, in which he abandons his hypothesis of two linear magnets, by which he had imagined he could account for the magnetic phenomena of the globe. M.

Kuppfer announces that he is employed in examining the various observations which have been made on the magnetic needle.

It has generally been supposed that the magnetic power could only be lost by heat; but M. Kuppfer has ascertained that it may be equally affected by cold.

Thence, in order to compare needles properly, they should be exposed to the two extremes of temperature, by plunging them first into boiling water, and then into a frigorific liquid, at 20° below zero.

It has, however, been already observed, that magnets sustaining a great weight have let it fall when the temperature has suddenly fallen.

M. de Humboldt then presented a Chinese Almanack for 1832, calculated by the Astronomical Tribunal of Pekin, in which the different days are placed under the protection of 34 genii.

Particular days are designated for giving entertainments; others are pointed out as propitious for feeding on dogs; others for marrying, for building, for pulling down, etc. M. de Humboldt added, that when the Chinese authorities were asked whether they should take any precautions against the cholera, they replied, that fear alone was the cause of people being attacked by it, and that therefore no preventive measure ought to be adopted.