not exceed. With the exception of one spot, the shores are generally shelving. The mountains and plains are generally covered with accumulated debris, and the soil, which is poor, corresponds to the rocks from which it is derived; the water is pure, and of the mean annual temperature of the place where it rises, except in the neighbourhood of Trincomalee, where there are hot springs of 103° to 137°.

The valleys are in general narrow and deep, with outlets which render them incapable of forming lakes; but there are some salt lakes formed by the sand banks thrown upon the sea

shore.

Besides the two species of rock before spoken of there are masses of granite, both common and graphic, sienite, felspar, rock, and greenstone.

Iron in different forms is general in the island, but no other metal has been discovered: its poverty, however, in this respect is not less remarkable than its richness in rare and valuable gems, which are scattered through the alluvial ground, but are seldom found in their native rock. The minerals which have been observed by Dr. Davy are quartz, cat's-eye, prase, hy alite, &c. Tourmaline, garnet, pyrope, cinnamon-stone, zircon, hyacinth, spinelle, sapphire, and common corundum, several varieties of felspar, mica, carbonate and anhydrous sulphate of lime, apatite, graphite, and ceylonite. No traces are visible of volcanic action in any part of the island.

A communication was read from Ed. L. Irton, Esq. of Irton Hall, on a third sand-tube found at Drigg.

The remains of this tube were discovered about 10 or 15 yards nearer to the sea than the former ones. Passing through about four feet of pebbles, its course was continued nearly eight feet through wet sand; it then became much contorted and irregularly formed, sometimes being solid, and again becoming tubular, and terminating at a granite pebble with only a small diverging ramification extending but a few inches.

SOCIETY FOR THE ENCOURAGEMENT OF ARTS, MANUFAC TURES, AND COMMERCE.

We hope in future to present our readers with notices of the more important communications made to this Society, and to which the Society has voted rewards. Since the commencement of the present session, in November last, rewards have been adjudged for the following interesting subjects.

Mr. W. Hardy's Inverted Pendulum.-This valuable instrument has already been made known to the public by Capt. Henry Kater, F.R.S. in a late paper in the Transactions of the Royal Society, containing "An Account of Experiments for determining the Length of the Pendulum, vibrating Seconds, in the Latitude of London; who derived considerable ad vantage from it, in proving the stability of the support for his

pendulum. It has also received the approbation of other eminent men in the scientific world. The Society adjudged its gold Isis medal, to be presented to Mr. Hardy, for this invention.

Mr. Einslie's Ivory Paper.-This paper possesses a surface, having many of the valuable properties of ivory, and at the same time has the superior advantage of being obtained of a much greater size than ivory can possibly furnish, even nearly as large as the usual sheets of drawing paper. The Society has voted the sum of 30 guineas to Mr. Einslie for this invention.

Mr. Alexander Bell's New Chuck for a Lathe.-This instrument can be screwed into, or upon, the mandrel of a lathe, and has three studs projecting from its flat surface, forming an equi-lateral triangle, and which are capable of being moved equably to, or from, its centre. These studs are provided with teeth, and can be made to embrace, or enclose, any hollow, or solid, circular body between them, within the extent of its limits, and retain it firmly, in order to turn, bore, or operate, in any other manner upon it in the lathe. From the greater simplicity of its construction, it can be made much cheaper than similar contrivances for the same purpose. The Society awarded its silver medal and the sum of 10 guineas to Mr. Bell for this

invention.

ARTICLE XII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS CONNECTED WITH SCIENCE.

I. Method of determining the Specific Gravity of the Gases. The apparatus necessary for taking the specific gravities of gases, by the following method, consists of a delicate balance, or rather beam, so constructed that two bulky vessels of exactly the same size and weight may be conveniently suspended from its extremities. One of these vessels may be a globe, or flask, furnished with a stop-cock as usual, and of any convenient size. The other must be cylindrical, so as to admit of being graduated; say, into 1000 equal parts; and must be likewise furnished with a stop-cock having an extremely minute aperture.

The two vessels, as before stated, must be exactly of the same size and weight, so that, when filled with atmospheric air and suspended, the index of the beam shall stand at 0, and these easy adjustments are the whole that are required. When used, the globe, or flask, is to be filled with the gas, whose specific gravity is to be determined in the usual manner, and the cylindrical vessel is then to be so far exhausted as to be rendered lighter than the globe, or flask, thus filled. Both vessels being now suspended, one at each extremity of the beam, the stop-cock of

the cylindrical vessel is to be opened, and so much air be permitted to enter by the minute aperture above-mentioned as shall be requisite to bring the two vessels in the same exact equilibrium as at the commencement of the experiment. The cylindrical vessel is then to be removed from the beam, and its stop-cock opened under mercury, and thus the precise bulk of air contained in it be accurately measured, which bulk (if the whole vessel has been graduated to 1000 parts) represents the specific gravity of the gas weighed, common air being 1000. Thus, suppose hydrogen to be the subject of experiment, and it be found that 69-44 parts of common air be equal in weight to 1000 parts of hydrogen, the specific gravity of hydrogen will be ⚫06944 common air by 1.000, or it is 14-4 times lighter than common air.

The above form of the apparatus is more particularly adapted for determining the specific gravity of gases lighter than common air; but it is obvious that the principle upon which the method is founded is equally applicable to gases heavier than air, by a little modification in the apparatus. The advantages of the method are many and important. Besides the greater general accuracy attainable by measuring than weighing gases, the use of weights, as well as the necessity of ascertaining the bulk and weight of the apparatus, as in the common mode of determinig the specific gravity of gases, are entirely superseded; nor are errors likely to arise from any change in the atmospheric temperature, or pressure, occurring during the performance of the experiment.

II. Sulphate of Strontian.

This substance has been lately found in considerable quantity at Carlisle, about 34 miles west of Albany, state of New York, imbedded in clay slate, forming very extensive strata. It was first tried by a common smith as a substitute for borax, and has been found the most useful flux ever employed in brazing and welding. By employing a very small quantity of it in powder, instead of clay, he welded easily the most refractory steel; and in brazing, it proved superior to borax, on account of its remaining more fixed at a high temperature.

III. Subterranean Noises.

At Haddam, in Connecticut, for several years past, noises, like the firing of small arms, have been continually heard, which have been accompanied with almost continual concussions of the earth. So frequently have these effects been experienced, that they are quite disregarded by the inhabitants. About six years since, however, a serious explosion took place, which rent and dislocated large masses of the granite mountains.

IV. Scientific Expedition in America.

A scientific party will proceed in March to explore the natural productions of the numerous large rivers tributary to the Missis

sippi. They will go in a steam-boat now building for the purpose at Pittsburg; and expect to be absent for upwards of three years. T. Say, Esq. of Philadelphia, will be one of the party.

V. Mineralogy in America.

We observe in the American papers proposals from Dr. J. W. Webster for a course of lectures on mineralogy and geology at Boston; and are happy to observe the science acquired in the university of our northern metropolis, during the intervals of professional studies, becoming actively employed in a district, we apprehend, abounding in minerals in considerable variety.

VI. Africa.

Mr.T. E. Bowditch, who has recently published his travels in Africa, is about to return to Cape Coast Castle, accompanied by Messrs. Williams and Salmon, surgeons. These gentlemen are all good naturalists; and will make frequent excursions into the interior with the view of exploring its natural history.

VII. Temperature of Bombay.

An account of the state of the barometer and thermometer, &c. in this island for 1816 and 1817, was given in the Annals for Sept. last by Mr. Knight. The following additional observations recently published, though made long before, may not be altogether devoid of interest.

Mean temperature of the island as estimated from the averages of observations made during a period of two years, viz. 1803 and 1804.

82층 울금

802 18

0

814° 38%

30

80/1/ 9

.

Average 793%

General average of 1803.

General average of 1804.

Mean temperature...... 803 8

The morning observations were generally made between six and eight o'clock, the noon between 12 and 4, and the evening between half-past 9 and 12, and the greatest height at noon was noted when several observations were made. The thermometer is stated to have been placed out of the direct influence of the sun about 23 feet above the level of high water mark.

It appears that the greatest diurnal range of the thermometer during the above period varied from 51° to 1310, the least diurnal range occurring from April to October, and the greatest from November to March. With respect to the above mean temperature, the author observes that it is a more favourable one than from observations in other parts of India or of the world in the same latitude, we should have been warranted in VOL. XIII. N° II.

K

supposing, and that the morning average in particular can hardly be relied upon as conveying an accurate idea of the morning temperature.

The following table presents the number of rainy days in 1803 and 1804, years remarkable for the difference in their great leading features, the first being a year of unusual scarcity, the second of uncommon abundance.

The author considers the difference of the fall of rain in the months of September to have been the chief cause of the above-mentioned difference between the crops of the two years.(Abstracted from a paper by Lieutenant Colonel Jasper Nicholls in the Transactions of the Literary Society of Bombay.)

VIII. Population of Bombay.

The whole population of Bombay, at the period below-mentioned, was estimated to vary from 160,000 to 180,000. Of this number, about were Mussulmen, of Parsee caste, and Christians; the remainder were chiefly Hindoos, who thus constituted the great bulk of the inhabitants. The following is a general account of the number of deaths from 1801 to 1808 inclusive. It is founded on returns made to the police office of

the number of bodies buried or burned in the island.

"The average deaths during the year would, by this account, be 9,000, or about 1 to 19; but the year 1804 in which the deaths are nearly trebled, was a season of famine throughout the neighbouring provinces on the continent of India. Great