LXXX. Abstract of a Letter to Mr. Benjamin Wilson, F. R.S. concerning Electricity; from Mr. Torbern Bergman,* of Upsal. p. 907. From the Latin. Dr. Franklin, in the 28th article of his 3d letter, wonders that a piece of ice, or an icicle, does not transmit the electric virtue, since water does it so well. But I, says Mr. B., have made some experiments, which show that a small quantity of water is not sufficient for this purpose. Thus, take a glass tube of 3 or 4 feet long, such as a barometer tube; fill it with water, and stop both ends by a perforated metal thread entering a little way into the water, as appears in the A-E A two persons, disposed as in a circle for making an explosion, hold the ends of the metal threads A, A, and try to make the evacuation, yet this will not perfectly take place, for hardly the wrist, and very seldom the elbow will be shocked by this method. But augmenting the capacity of the tube, it transmits more, until it thus increases, so as to permit a full and free passage. It follows, This distinguished philosopher, who so greatly enlarged the bounds of chemical knowledge, and introduced into chemical analysis a degree of exactness unknown before, was a native of Sweden, and was born in 1735. He studied at Upsal, where he qualified himself for the medical profession, and took the degree of M. D. It does not appear however that he ever engaged in the exercise of the medical profession; but devoted himself to the pursuit of general science, and, after some years, to the study of chemistry. In 1761 he was appointed professor of mathematics and natural philosophy at Upsal; and about 6 years after, he succeeded Wallerius as professor of chemistry and mineralogy in the same university. About this time (1767) he published in the Stockholm Transactions his memoir on the crystallization of alum; and afterwards, for the space of 17 years, he continued to publish from time to time (till within a year of his death, which happened in 1784) various chemical dissertations, either separately, or in the Swedish Transactions before mentioned. To the inexpressible regret of the philosophical world, his life, (like that of his contemporary Scheele) was shortened by his unceasing application to chemical pursuits, he being only in his 49th year, when he died. Among his principal works may be mentioned his Opuscula Physica et Chemica, 3 vols. 8vo; his Sciagraphia Regni Mineralis; his treatise De Attractionibus Electivis, (of all which there are English translations) and his Physical Description of the Earth, 2 vols. 8vo. published in the Swedish language. Ingenuity, accuracy, industry and method are conspicuous in all the writings of Bergman; his labours were extended to a vast variety of subjects, in all of which he made large additions to the stock of chemical knowledge. Had he done no more than publish his Treatises on Elective Attrac tion, on the Blowpipe, and on the Method of Assaying in the Humid Way, he would still have ranked high among the chemists of the 18th century; but when we call to mind his experiments on earths, gems, and metals (including those on metallic precipitates), and his analyses of mineral waters, and the methods of preparing them artificially, (not to mention his experiments and observations on the acid of sugar, the aerial acid, &c. and his improvements in nomenclature) we cannot but regard him as one of the greatest chemists which any country or age has produced. therefore, that water, as well as ice, when in small quantities, with difficulty transmits the concussion. Hence I suspected that a great quantity of ice would permit an easier transit, which was indeed proved by experience, though hitherto without using a piece larger than to give a shock to the elbows. But, of equal quantities of water and ice, the ice transmits the less. LXXXI. Some Considerations on a late Treatise intitled, A new Set of Logarithmic Solar Tables, &c. intended for a more Commodious Method of finding the Latitude at Sea, by Two Observations of the Sun. By H. Pemberton, M. D. R. S. Lond. et R. A. Berol S. p. 910. As it happens not unfrequently, at sea, for the unseasonable intervention of clouds to prevent the ordinary method of determining the ship's latitude by the sun's meridian altitude, even when it is of primary consequence that the true latitude should be known; a problem for remedying this disappointment is stated in many treatises of navigation, for finding the latitude of a place by any two altitudes of the sun, with the interval of time between them. A problem similar to this is proposed, and solved instrumentally on a globe, by a very early writer, Petrus Nonius, namely, to find the latitude by two altitudes of the sun, and the angle made by the azimuth circles passing through the sun, when the altitudes are taken. And since more commodious and accurate instruments for measuring time have been invented than were known to this author, the other problem has been proposed for the same purpose, of which a construction on the principles of the stereographic projection of the sphere is exhibitted by Mr. Collins, in his Mariner's Plain Scale new planed. And as the direct method of solving both these problems by numbers requires a diversity of trigonometrical operations, a set of tables has lately been published for a more compendious way of computation in the problem, where the interval of time was given, by which the ship's true latitude may be very expeditiously derived from the ship's dead reckoning, provided the observations are made within certain limits of time. But however worthy of notice this method may be, new tables for the purpose are altogether unnecessary. It consists of two parts: the first computes, from the latitude exhibited by the dead reckoning of the ship, the distance from noon of the middle time between the observations, and thence the time of either: the 2d operation computes, from one of these observations, what should be the sun's meridian altitude, had the ship's reckoning given the true latitude, but if the latitude assumed from that reckoning is erroneous, the altitude thus computed will not be comformable to it; however, if the times for the observations are properly chosen, it will much better agree to the true latitude, and thence the assumed latitude may be more or less corrected. But both these operations are an immediate consequence from the proposition in spherical trigonometry, usually delivered under the name of the 4th axiom, which is this: that the square of the radius is to the rectangle under the sines of the sides containing any angle, as the versed sine of that angle is to the difference between the versed sines of the third side, and of the difference between the sides containing the angle. Hence Dr. P. institutes a rather long and laboured geometrical dissertation, to show how the set of tables in question are, or might have been constructed. LXXXII. Of the Plants Halesia and Gardenia. In a Letter from John Ellis, Esq. R. R. S., to Philip Carteret Webb, Esq, F. R. S. p. 929. The intent of this letter is to exhibit the characters of two new genera of plants, growing in Mr. Webb's garden, which Mr. Ellis calls after Dr. Hales of Teddington, and Dr. Garden, of Charlestown, South Carolina.* The first of these is thus described by Dr. Garden, when he sent the specimens and seeds. "This beautiful tree grows commonly along the banks of Santee river, and rises often to the size of middling mulberry-trees. I have seen it sometimes more southerly, near the small rills of water; but of a much smaller size than that which grows on Santee. The wood is hard and veined; the bark is of a darkish colour, with many irregular shallow fissures. The leaves are ovated and sharp pointed, with the middle depressed, growing alternately on short footstalks. The flowers hang in small bunches all along the branches, each gem producing from 4 to 8 or 9 flowers, bell-shaped, and of a pure snowy whiteness. As they blow early in the spring before the leaves appear, and continue for 2 or 3 weeks, they make a most elegant appearance. They are followed by pretty large four-winged fruit, which likewise hang in bunches, each containing 4 kernels that are very agreeable to the taste." This tree is mentioned by Catesby, vol. 1. p. 64, and called Frutex padi foliis non serratis, floribus monopetalis albis, campaniformibus, &c. &c. Mr. E. had not heard that it was cultivated in England, till about 4 years before, when the Doctor sent him over from Carolina a large parcel of the seeds, which he distributed among many curious gardeners, and others: but he could not find any one that it had succeeded so well with as Mr. Gordon, gardener at Mile-end, a man who seems to be possessed of a knowledge peculiar to himself, in raising all the rarer and most difficult exotics from seeds, layers, or cuttings. He informs Mr. E. that it stands our winter in the open air, without shelter. * It is the Halesia Tetraptera of Linneus. The other plant is known by the name of the Cape Jasmine,* and is the most rare and beautiful shrub, that has yet been introduced into the European gardens, as well for the refreshing aromatic smell of its milk-white flowers, as the perpetual verdure of its leaves, which are like those of the lemon-tree. It promises, from the thickness and woodiness of its stem, together with its free manner of growing, to become a shrub of 6 or 7 feet high. It bears but one flower at the end of a branch; and the leaves grow opposite to each other on the branches. We are indebted to Capt. Hutchinson, of the Godolphin Indiaman, for this curious discovery, who, about 6 years ago, found it growing nearthe Cape of Good Hope, and, on his arrival here, presented it to Richard Warner, Esq. of Woodford, Essex; who finding great difficulty in propagating this valuable plant, either from cuttings, or by inarching it on the yellow Indian jasmine, as he had been advised, Mr. E. recommended him to try Mr. James Gordon, gardener at Mile-end; and, at the same time (August 1757,) by the interest of Gustavus Brander, Esq. F. R. S., he procured two cuttings of it for Mr. Gordon. These, with two more, which he afterwards received, he increased to so considerable a number, that, in order to dispose of them, he advertised for sale at 5 guineas a plant; and has had such success in the sale, that, reckoning the value of the plants on hands (with a proper allowance for the falling of the price, as they become more plenty,) he computes this plant will be. worth at least £500 sterling to him. Having dissected many dried as well as fresh specimens of this rare plant, Mr. E. found sufficient evidence (notwithstanding the flowers being double) to prove, that it belonged to quite another class of plants, as different from the jasmine as the rose is from the peony: that the fruit was below the receptacle; instead of being above it. Linneus says this plant belongs to the natural order of contorted flowers, that is, to those monopetalous flowers whose lobes, or sections of the limb of their petals, turn all to the right hand; such as the Nerium, Plumeria, Cerbera, Cameraria, Vinca, &c. and that it should be placed next to the Cerbera. Mr. George Dionysius Ehret, F. R. S., published a most elegant plate of this plant, by the name of, Jasminum? ramo uniflore pleno, petalis coriaceis, with a note of interrogation, as a quære, before the word jasminum; leaving the determination, whether it is a jasmine or not, to a future inquiry. Fig. A, pl. 15, represents the gardenia with a single flower, drawn from a dried specimen in the British Museum. B, the same in fruit. c, a capsula with five divisions in the calyx. D, the same cut across to show the seeds lying in the two loculaments. E, the seeds. * The Cape Jasmine, as it is commonly called, is the gardenia florida of Linneus. LXXXIII. An Eclipse of the Moon, Nov. 22, 1760, observed in SurreyStreet, Strand, London. By James Short, M. A., F. R. S. p. 936. Moon's diameter almost parallel to the horizon = 3′ 51′′ at LXXXIV. The Case of a young Man, who had lost the Use of his Hands by Cleansing Brass Wire. By Mr. Samuel More, Apothecary in Jermynstreet. p. 936. The disorders to which mechanics are unavoidably subjected by their employments, have exercised the pens of several ingenious writers; among whom Mr. M. would not presume to appear, but that he hopes the publishing the following case may be of some service: for he is certain, every one, who has been in the least conversant with the labouring people of London, must frequently have observed their hands in a condition something resembling, though perhaps not quite so bad as, that of the young man, whose disorder is the subject of the following paper. And as there is great reason to believe that the complaint, here treated of, frequently happens to persons employed in the dyeing business, they will hereafter have a method of cure laid before them, which, with little expence, will probably be of great service to them. And, on that consideration only, he had been induced to submit this account of the disease to the public. It is proper first to premise, that in drawing brass wire for the pin-makers, the frequent passing it through the fire to anneal it, covers it with a crust, which it is necessary to take off, before they can make use of it; and, for this purpose, it is sent to the dyers, who letting it lie for some time in the liquor with which they have dyed what they call Saxon colours, (which liquor is composed of water, oil of vitriol, alum, tartar, &c.) and then throwing it forcibly 3 or 4 times against the gronnd, the crust is, by degrees, broken off, and the wire rendered bright and fit for use. The gratuity given for this is generally allowed to the apprentices; and in this work Francis Newman had frequently at his leisure hours employed himself, till about the month of August 1759, when the cuticle on the palms of his hands, and the inside of his fingers, was become so hard and rigid, that he was no longer capable of doing either this or any other business. For relief of this disorder, he applied to the person who attended the family in capacity of apothecary, who gave him several doses of purging physic, but without success. He was next admitted an out-patient of St. Thomas's hospital, |