« AnteriorContinua »
processes were disposed to contract, it would be much too short to produce any sensible effect. What their use may be cannot easily be determined: if it were necessary to have any peculiar organs for secretion, we might call them glands for the percolation of the aqueous humonr; but there is no reason to think them requisite for this purpose.' 8.78.
Some other remarks on the eyes of fishes, insects, &c. are added; but we shall prefer transcribing our author's own recapi
· First, the determination of the refractive power of a variable medium, and its application to the constitution of the crystalline lens. Secondly, the construction of an instrument for ascertaining, upon inspection, the exact focal distance of every eye, and the remedy for its imperfections. Thirdly, to show the accurate adjustment of every part of the eye, for seeing with distinctness the greatest possible extent of objects at the same instant. Fourthly, to measure the collective dispersion of coloured rays in the eye. Fifthly, by immerging the eye in water, to demonstrate that its accommodation does not depend on any change in the curvature of the cornea. Sixthly, by confining the eye at the extremities of its axis, to prove that no material alteration of its length can take place. Seventhly, to examine what inference can be drawn from the experiments hitherto made on persons deprived of the lens; to pursue the inquiry, on the principles suggested by Dr. Porterfield; and to confirm his opinion of the utter inability of such persons to change the refractive state of the organ. Eighthly, to deduce, from the aberration of the lateral rays, a decisive argument in favour of a change in the figure of the crystalline ; to ascertain, from the quantity of this aberration, the form into which the lens appears to be thrown in my own eye, and the mode by which the change must be produced in that of every other person. And I Aatter myself that I shall not be deemed too precipitate in denominating this series of experiments satisfactorily demonstrative. P. 82.
III. On the necessary Truth of certain Conclusions obtained by Means of imaginary Quantities. By Robert Woodhouse, A.M. Fellow of Caius College Communicated by the Rev. S. Vince, A.M. Plumian Professor of Astronomy in the University of Cambridge.'
We have read with pleasure this ingenious defence of mathematics against those who reproach its paradoxes, and ridicule its impossible quantities, which are admitted as means of attaining veracity. We cannot however give any account of it which will satisfy the reader who has not made mathematical inquiries the object of his attention; and a mathematician can only read it with advantage in the work itself.
IV. On the Production of artisicial Cold by Means of Muriate of Lime. By Mr. Richard Walker. Communicated by Henry Cavendish, Esq. F.R.S:'
We have already noticed M. Lowitz's very singular discovery of the great cold produced by adding muriate of lime to show or pounded ice. Three parts of the former to two of the latter sunk the thermometer to 50, and quicksilver in large quantities was frozen by this experiment. Mr. Walker has succeeded in repeating the experiment, and, by operating on 2 mixture previously cooled, has produced a temperature so low as 91-perhaps the lowest degree ever procured by human art. He then tried the muriate of lime, prepared so as to continue solid during the summer, and produced, by five parts of the salt to four of water, 29 degrees of cold. At any time therefore, in the summer, water may be reduced to 21 degrees of Fahrenheit, 11 degrees below the freezing point; and by employing ice thus procured, with some necessary precautions, mercury may be frozen in the hottest summer day.. A view of the general effects of the different frigorific mixtures is added, and a postscript, announcing that ice formed on the outside of a vessel containing the frigorific mixture is transparent, while that produced from a fluid immersed in the mixture is usually opaque. The solution is, that it is frozen more slowly; but Mr. Walker generally throws an air of importance over common observations.
·V. Account of a monstrous Lamb. In a Letter from Mr. Anthony Carlisle to the Right Honourable Sir Joseph Banks, Bart. K.B. P.R.S.'.
This lamb was an extraordinary production, but by no means singular. It wanted wholly the cerebrum and the head. It had two external ears, and the remains or rudiments of the small bones of the ear between these organs. One passage led from the external parts to the oesophagus and larynx. The cerebellum was perfect. —The following remarks are judicious and philosophical. We could, we think, did our limits permit, pursue them with some success,
• The narration of these appearances assists and confirms other facts, in demonstrating that the forination and growth of animals in the uterus are independent of any influence from those parts of their brain which properly belong to sensation. We have to regret that this animal did not live to show the phænomena of volitions di. rected to its limbs, and other apparatus, without that intelligence froin the organs of the senses which regulates and directs the efforts of perfect animals. The careful observance of such circumstances may in future bring us to discoveries of the highest value, in that part of physiology which is now enveloped in deep mystery: the facts at present collated are not sufficient. The intellectual phænomena of persons who sustain known injuries of particular parts of the brain; the appearances on the dissection of ideots, with their mental particularities; the anatomical history of maniacs--all promise, when properly cultivated, a series of truths, which it may not be 1801. extravagant to hope will open sublime views into those recesses of our construction which justly rank among the most curious, if not the most important objects of research.'. P. 142.
VI. An anatomical Description of a male Rhinoceros. By Mr. H. Leigh Thomas, Surgeon. Communicated by George Fordyce, M.D. F.R.S.
The description before us is in a great degree new, at least to the English reader; for there is more than one dissection of the rhinoceros described by French anatomists, though, if our recollection serve, the accounts are not so full as in the present article. The animal died of an inflammation in the lungs; and, when alive, showed no attachment even to the person who fed it, but continued torpid, and apparently stupid. The anatomy, in general, corresponded to that of the horse. The cæcum was however much larger, and the internal parts of the stomach lined with a secreting membrane. The intestines were short, but their surface greatly increased by long processes, resembling the valvulæ conniventes. The liver was very soft, but this might have arisen from an unnatural mode of living. The urinary organs were apparently very simple in their structure, as an injection passed into the ureter, though urged with little force. From the convex side of the penis being towards the body, this animal must have been a retrocoient.
• Whilst the animal was living, the eyes always appeared dull and watery; the upper and under palpebræ were scarcely ever observed to come together; the palpebra tertia was frequently carried over the cornea, and corresponded in shape and structure to that of the ox. The muscles of the eye-ball were exactly similar to those of other graminivorous animals: the globe of the eye was not larger than that of the sheep; and the cornea was much smaller. Upon cutting through the sclerotic coat, it was found somewhat harder and thicker than what is observed in the sheep; and, upon endeavouring to separate it from the choroid, I found an uncommon resistance at the posterior part of the eye; though in other parts the adhesion between the coats appeared less than what takes place in the human body. This unusual connexion naturally directed my attention more particularly towards it; when I readily discovered four processes, arising by distinct tendons from the internal and posterior portion of the sclerotica, and at equal distances from the optic nerve. These processes passed forwards between the coats, gradually becoming broader, and being insensibly lost in, and form. ing a part of, the choroïd, at the broadest diameter of the eye; the connexion between the coats around the outer circle of the cornea was the same as is observed in the eye of other animals. The processes had a muscular appearance-the fibres running forward in a radiated direction; they were detached from the coats with the greatest facility, except at their origins and insertions, where it required considerable force to tear them from the sclerotica; and, at
their terminations, they became so intimately connected with the choroid, as to form only one substance. On neither of their sur. faces was there any thing similar to the nigrum pigmentum; the pigment was confined to the inside of the choroid coat, without any structure similar to the tapetum lucidum. The ciliary processes were affixed to the crystalline lens; they were extremely short and indistinct, not having that beautiful arrangement commonly seen in the eye of other quadrupeds. The iris was circular, and of a dark brown colour. The crystalline lens was somewhat remarkable, with respect to its form being nearly spherical; this was very strongly marked, when compared with the lenses of several other animals: the anterior surface was a little fattened.' P. 149. · These processes are apparently muscular; but what influence such appearances may have on the theory opposed by Dr. Young in the present volume, we cannot stay to inquire. .
VII. Demonstration of a Theorem, by which such Por- . tions of the Solidity of a Sphere are assigned as admit an Alge, braïc Expression. · By Robert Woodhouse, A. M. Fellow of Caïus College, Cambridge, Communicated by Joseph Planta, Esq. Sec. R.S.
The demonstration of this theorem is incapable of abridge, ment. :
VIII. Account of the Discovery of Silver in Herland Copper Mine. By the Rev. Malachy Hitchins. Communicated by the Right Hon. Sir Joseph Banks, Bart. K.B. P.R.S.'
The silver is contained in the cross lode, chiefly on the eastern side, and it raises the copper lode. The silver ore is a mixture of galena, native bismuth, grey cobalt ore, vitreous silver ore, and native silver, in the same proportions as they are arranged. The rest of the lode is quartz, intermixed with iron, manganese and wolfram, with a small proportion of cobalt and antimony. As the lode of silver dips so low, it is not likely to be very productive, especially if there be no greater powers of raising water than the present steam engines possess,
IX. Account of an Elephant's Tusk, in which the Iron Head of a Spear was found imbedded. By Mr. Charles Combe, of Exeter College, Oxford. In a Letter to the Right Hon. Sir Joseph Banks, Bart. K.B. P.R.S.'
It is not uncommon to find balls in the tusks of elephants; but we do not remember having ever heard of a weapon, urged only by human action, being lodged in this hard substance. Mr. Combe properly supposes that it penetrated through the skull contiguous to the root of the tusk.
X. Description of the Arseniates of Copper and of Iron, from the County of Cornwall. By the Count de Bournon. Communicated by the Right Hon. Sir Joseph Banks, Bart. K.B.P.R.S
• XI. Analysis of the Arseniates of Copper and of Iron, described in the preceding Paper; likewise an Analysis of the red octaëdral Copper Ore of Cornwall; with Remarks on some particular Modes of Analysis. By Richard Chenevix, Esq. M. R. I. A. Communicated by the Right Hon. Sir Joseph Banks, Bart. K. B. P. R. S.'
These papers are very satisfactory, and show very clearly the great importance of crystallography, as analysis fully confirmed the arrangement deduced from the crystalline forms. Count de Bournon seems to be a very experienced crystallographer. The arseniates of copper are little known; they are not mentioned by Fourcroy in his late very comprehensive work, and we do not find any mention of them in the abbé Hauy's excellent system, now under our hands, and which we hope to be able to introduce to the English reader in our next Appendix. They occur however in Klaproth's Short View of the Mineralogy of Cornwall, long since translated and noticed in our journal.
It is with great regret we find it totally out of our power to follow the very able author of the former paper in all his remarks. We can only observe, that he notices four species of arseniates of copper;- 1. That in the form of an obtuse octaëdron; 2. In hexaedral laminæ with inclined sides; 3. In the form of an acute octaëdron; 4. In the form of a triedral prism.
The arseniates of iron are still more rare. These were supposed by Klaproth to be arseniates of copper; but the real ingredient is iron, and the copper seems only to be an accidental mixture. The first species, the simple arseniate of iron, crystallises in perfect tubes, sometimes, though rarely, a little flattened. The form of the second species is a rhonboïdal tetraëdral prism, two edges of which are very obtuse, and the two others very acute.
Of Mr. Chenevix's very laborious and scientific paper we are still less able to give a satisfactory analysis; for it is full of minute chemical erudition, and displays a very particular and comprehensive view of his subject in many points. The third species of the preceding paper is the most simple, containing only oxide of copper and arsenic acid, in the proportion of 60 to 39.7. The fourth species contains less copper and a proportion of water, in which some of the varieties of the third species agree. The second species contained also oxide of copper, arsenic acid, and water. The first species was of the same nature, differing only in the proportions. Various other analyses of similar ores are added, which we cannot follow. We shall therefore conclude our account of this part of the paper with two very important extracts.
• With regard to the colour of some specimens of arseniate of copper, it is easily to be accounted for upon chemical principles.