Scotland, and gives to the circle of perpetual congelation an altitude of 7791 feet, a statement contradicted by facts." Now, in this bold remark, Dr Latta first ascribes to me a statement I never made, that I am aware of; then bluntly says, that it is contradicted by facts! I do mention it, indeed, as a remarkable circumstance, that, on mountains of 3000 feet elevation in Spitzbergen, the snow should sometimes be wholly dissolved at their summits, when, in so much lower a latitude, Ben-nevis should occasionally exhibit a crest of snow throughout the year (Vol. i. p. 123.) But I nowhere reason myself into the supposition that the climate is therefore warmer. I only reason that "the upper line of congelation, where frost perpetually prevails," is much higher on the Arctic lands than was to have been expected from its mean temperature. And, applying the known law of diminution of temperature, on ascending in the atmosphere, to the summer heat of Spitzbergen, I observe, that "it will require an elevation of 7791 feet for reducing that temperature to the freezing point;" and hence I reckon this to be about the altitude of perpetual freezing,p. 126. What facts Dr Latta can bring forward, to shew that a thawing temperature never occurs so high, I know not; especially when, by observation of the thermometer, I found the temperature in Spitzbergen so high as 37° Fahr, at mid-night, at an elevation of about 3000 feet. Not thinking it right to allow a bold assertion, which I believe to be unfounded, to pass before the Society as correct, nor an assertion declared to be dependent upon facts to retain such a basis, unless these facts can be substantiated, I have ventured to trouble the Society with these remarks. Besides, I acknowledge my feeling to be that which is no doubt common to authors, greatly averse to the charge of such theorising views as to be capable of reasoning myself into conclusions contradicted by facts; an equal aversion, also, to be charged with asserting what, to the best of my knowledge, I never did. As such, I think it behoves Dr Latta, either to bring forward the facts which contradict my statements, or to have the candour to acknowledge the mistake he has fallen into. On the Coniometer. Professor JAMESON. MY DEAR SIR, In a Letter from Professor LESLIE to HAVING just seen a paragraph in the Annals of Philosophy for March 1827, copied from the Annales de Chimie et Physique, in which my contrivance of an instrument to measure the specific gravity of powders is reclaimed for M. Say, Captain of Engineers, who, it seems, perished in the famous Egyptian Expedition; I trust you will allow me to offer some explanation. I was aware that attempts had been made to apply' the law of Mariotte, in ascertaining the specific gravity of a substance which could not be immersed in water, but supposed them to have proved unsuccessful; and all this I stated at the time to the persons who witnessed my experiments. When I first visited Paris in 1802, my kind friend the late M. Guyton-Morveau shewed me an apparatus for that purpose; and it then appeared to me very clumsy and unmanageable. I have no recollection of the nature of its construction, and only a sort of faint impression that it was somehow connected with an air-pump. Indeed, were it worth while, I could easily point out two several methods of discovering, by help of a good air-pump, the absolute bulks, and consequently the specific gravities, of powders and very porous substances. I have now looked into the article referred to in the 23d volume of the Annales de Chimie, and will most readily admit, that the Stereometer of M. Say is substantially the same as my Coniometer. But of this coincidence I was quite unconscious, when I designed my instrument. I made no boast of discovery, and only mentioned it as a simple contrivance, which could be directed to some very useful and curious researches. I permitted, indeed, a gentleman who admired its application, to draw up a popular description of it in his own way; but I deferred giving any account of it myself, till I had brought it to greater perfection, and was enabled to produce a series of correct and interesting results. So little, however, did it engage my attention, that I have suffered it to remain nine months for alteration, in the hands of the artist. A year has nearly elapsed before any chemical philosopher has challenged its originality; and Dr Thomson, Regius Professor of Chemistry at Glasgow, whose acuteness, memory, and extensive reading, are universally acknowledged, has, within these very few days, ordered his workman in Edinburgh to execute for him a copy of the instrument. For myself, I can positively aver, that I never chanced to light on the Memoir of M. Say; and that, although I have been very diligent, of late years, in collecting philosophical apparatus, I have not found any account of his stereometer in elementary works of science, or met with that instrument in the physical cabinets I have seen either at home or abroad. I suspect it has been confined to the Polytechnic School, and am yet to learn what sorts of experiments have been made with it. While I willingly concede, then, the right of priority, and cordially give to the late M. Say the praise of ingenuity and accuracy of conception, I must consider his stereometer as an imperfect project, and scarcely applicable, in its original form, to practice. The coniometer possesses several decided advantages over the instrument figured in the Annales de Chimie: 1st, The part for receiving the powder being long and narrow, the capsule is easily and nicely applied; but in the stereometer, the recipient is a broad shallow cup, the lid of which, fitting with difficulty, may shut up an undue share of air. 2dly, The long slender tube is easily pressed down into a wider one, containing mercury; whereas Say's instrument is plunged into an enormous cistern of mercury, or at least a very tall receiver. 3dly, In the coniometer, the scale engraved on the slender tube marks at once the absolute bulk of the powder or porous substance, or rather the weight of an equal volume of water; there is a sliding scale on the outer tube, and an adjustment for the variation of the altitude of the barometer. 4thly, The slender tube has besides another set of numbers engraved, corresponding to the triplication, as the former does to the duplication, of the volume of included air. By comparing the two results, we are enabled to determine, whether the air contained in the porous substance exists in a condensed state, and to calculate the degree of condensation. 5thly and lastly, The coniometer has already indicated some very curious and interesting results, which I regard, however, at present as only approximative. As soon as I have brought the instrument to a more perfect form, I purpose to institute a series of accurate experiments with it. In conclusion, I think, a journalist certainly entitled to remark, in a tone of right feeling, those coincidences which must at times occur in the history of science, when different persons happen to strike into the same path of inquiry; but to hunt incessantly after obscure, vague and distorted charges of plagiarism, only betrays the workings of a base and malignant disposition. I ever am, &c. (Signed) JOHN Leslie. List of Rare Plants which have Flowered in the Royal Botanic Garden, Edinburgh, during the last three months; with Description of a new species of Euonymus. Communicated by Dr GRAHAM. Banksia latifolia. serrata. Dichorisandra thyrsiflora. 10th March 1827. E. scandens; fruticosa, scandens, radicans; foliis lanceolato-ovatis, crenatoserratis, venis obliquis; pedunculis filiformibus, axillaribus bis (terve ?) dichotomis; germine scabro. DESCRIPTION. Shrub climbing to a great distance. Branches very long, cylindrical, green with brown scars, adhering to every thing in contact with them, by long, flattened, branching, white threads, which at first spring in linear tufts, but afterwards throughout the whole length of the branches, and hanging loose on all sides, conceal these in an entangled mass. Leaves opposite, somewhat decussating, the older ones somewhat coriaceous, the younger shining and membranous, bright green, and paler on the back, ovate or ovato-lanceolate, acuminate, crenato-serrate, the serratures being frequently, especially on the ovate leaves, compound, veins oblique, and, as well as the middle rib, prominent on both sides, reticulations at the edges most distinct on the under. Petioles channelled, approximate on the branches, distichous on the flowering-shoots (inch long); stipules minute, brown, lacerated, one on each side of the petiole; buds lanceolate, pointed, covered by imbricated blunt scales, some of which are persistent upon the base of the twig. Bractea small, awlshaped, brown, reflected, slightly fringed, with brown glands at their edges. Peduncles axillary twice (or thrice ?), dichotomous, filiform, angular, straight, nearly three times as long as the petiole. Calyx very small, green, tetraphyllous, segments rounded, persisting, at every period concave, and closely applied behind the bases of the stamens. rolla yellowish-white, 4-petalous, petals rounded, minutely toothed, reflected, attached by small claws, which are about the length of the calyx, and concealed. Stamens 4; filaments whitish and tapering, scarcely longer than the claw of the petals, at first erect, afterwards reflected, inserted into broad, flattened, green bases between the petals; anthers yellow, of two roundish lobes, about as long as the filaments. Germen flattened, yellowish-green, indistinctly warted. Stigma at first deep green and sessile, after the shedding of the pollen paler, blunt, and continuous with a stout, linear, furrowed style equal in length to the filaments. Co This species was received from the Botanic Garden, Calcutta, under the name here adopted, in 1823, its native country uncertain, probably Nepal. It approaches nearly to E. echinata and E. vagans of Flora Indica ; but is distinguished from the former by the oblique veins of the leaves, and from the latter by its rooting stem, and probably by its spiny fruit, though, as this has not yet ripened in the Botanic Garden, the appearance of the germen only can be stated. Liparia sphærica. Mirbelia speciosa. Penæa squamosa. Celestial Phenomena from April 1. to July 1. 1827, calculated for the Meridian of Edinburgh, Mean Time. By Mr GEORGE INNES, Aberdeen. The times are inserted according to the Civil reckoning, the day beginning at midnight. |
