nometer is made to traverse upon the plate of a compass-needle: Capt. S. has found this contrivance quite practicable, the magnet which directs the plate being at such a distance as not to affect the chronometer.

May 6.-Account of a Series of Electro-Magnetic Experiments, by Dr. TRAILL and Capt. W. SCORESBY.

May 20.-An Account of the Analysisof the Faroe Apophyllite and other Minerals, by M. BERZELIUS.-Observations on this Paper, and on the Optical Analysis of Minerals, by Dr. BREWSTER.

June 3.-Hints on the Subject of Dreaming, and on the Operation of the Mind in Dreaming, by H. MACKENZIE, esq.

The Nursery and Hot-Houses

Of Messrs. Loddige's, at Hackney, contain some of the most valuable plants and flowers from every part of the world. Among the curiosities of this tropical and exotic garden, is one of many extensive glass hot-houses, in which some of the trees rise in the ignited air of the place to the height of forty feet. Among them is a species of the palm, with its stately stem and wide pendant branches, filling the memory with classical recollections, and the imagination with its beauty. In addition to this novelty the enchanting nature of the scene is increased, when, at the instant it is desired, by touching a spring, water is heard and seen showering over the plants through the hot-house, pattering upon, and dripping from the leaves like a sudden rain in a grove on a calm summer day. It is from this grand nursery that the selection is made, from which Mr. G. Cooke has engraved, and is engraving, the flowers for the beautiful monthly publication, called the "Botanical Cabinet."

Copper raised in Great Britain, &c.

Damp in Walls.

163

THIN sheet lead, weighing from four to eight ounces the square foot, has been lately used to prevent the effects of damp walls upon paper, in rooms. It is fastened to the walls with copper nails, which, not being subject to rust, are very durable, and the whole may be immediately covered with paper.

Specific Gravity.

Mr. CREIGHTON, in the Journal of the Royal Institution, recommends a very and ingenious instrument for determining the specific gravities of solid bodies. It consists of two cages of wire, which are suspended the one under the other to a sensitive spiral spring. The lower cage being immersed in water, the weight of the body in air will first be indicated by the tension of the spring when it is placed in the upper cage; by then removing it to the lower one, its weight, in water, will be pointed out on the graduated scale. Mr. C. gives a formula for ascertaining the specific gravity from these two observations without recurring to the usual tedious calculations.

Quantity of Copper raised in Great Britain and Ireland.

For one year ending June, 1822.

Cornwall

Ireland, and sundry parts of England, sold at

Tons.

9140

Produce of the ores 8 per cent.

Average price of copper 1087. 15s. per ton.

Breaking Stones by Steam.

ON a new line of road, between Bury and Bolton, a patent rotatory steam-engine is attached to a machine similar to a bone-mill, but considerably stronger, which breaks the stones to cover the road at the astonishing rate of seventy or eighty tons in ten hours. The engine is mounted on wheels, so that it can be removed to any part of the road without being taken to pieces.

Curious Knife.

THE knife presented to Prince Leopold by the corporation of the town of Sheffield contains fifty instruments, moving on twenty springs and twenty-five joints, mounted in gold, and mother-of-pearl handle. It employed the workman thirty-six days of close application: weighs four pennyweights and a-half, and is only five-eighths of an inch in length.

Steam Vessels on Canals.

AN experiment has been lately made with a steamboat on the Union Canal, at Edinburgh. This boat was twenty-eight feet long, and constructed with an internal movement. It had twenty-six persons on-board; and, although drawing fifteen inches of water, she was propelled by only four men, at the rate of between four and five miles an hour, the agitation of the water being entirely confined to the centre of the canal,

Denmark,

The professors Oersted, Hornemann, and Reinhardt, have, in conjunction with Dr. Bredsdorf, determined upon the publication of a Journal of the Natural

4

On the Preservation of the Potato.

165

Sciences, six numbers of which will appear every year, Each number will contain from eight to ten sheets. The names of these gentlemen are a certain guarantee of the merit of the work.

Switzerland.

The Society for the Promotion of the Arts, at Geneva, have issued by their committee of the Class of Agriculture, a notice concerning the potato, which is deserving of attention.

The committee say, that convinced of the advantages which the cultivation of the potato affords, whether for the perfecting of agriculture, or as an efficacious means of providing, in times of plenty, an important resource in years of scarcity; they have desired to multiply the means of increasing agricultural produce, and at the same time to encourage the use of this tuberous root. Its conversion into a substance capable of being made into bread, and of being preserved for a long time, is, beyond a doubt, an important object.

The committee, called upon to record the benevolent views of the government, has published, at two different times, instructive information, designed to promote the grating of potatoes, and the conditions on which it will purchase them when grated; conditions which give for the potato, thus employed, a value very superior to what it is sold for in the market, and which gives to growers and speculators a considerable advantage. Notwithstanding these encouragements, a very small number of the sellers of potatoe gratings has yet ap peared. In searching for the cause of this indifference for a speculation as useful to the grater himself as to the republic, the committee believes that it consists

chiefly in the difficulty of drying the gratings, a difficulty, among others, which hinders small proprietors from pursuing an employment which would pay them well for their labour. In consequence of these considerations, the committee has thought it a duty to propose a special reward to him who shall point out the best and most economical processes for simplifying, abridging, and facilitating the desiccation of the gratings of potatoes. The committee desire that the methods pointed out may be supported by exact experiments; and that they may be of a nature to be applied to great and to small undertakings; and that they may be used in various

seasons.

The competitors must send, with their memoirs, samples of the gratings which they have obtained by the means which they describe; and, above all, an exact account of the expense of the procedure. In particular, the cost of the implements, &c. are necessary, as well as the time which the desiccation has required. The reward will consist in a medal of the value of five hundred florins, (about 231 francs). The memoirs must be sent to the Committee of Agriculture before the 1st of November, 1822,

New Patents sealed in 1822.

To William Mitchell, of the city of Glasgow, silversmith, for the discovery of a process whereby gold and silver plate, and other plate formed of ductile metals, may be manufactured in a more perfect and expeditious manner than by any process which has hitherto been employed in such manufacture.-Sealed August 24th.—-Six months for Inrolment.