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is prevented from reaching the retina, or from reaching it in a proper state of regular concentration, being stopped, confused, and scattered, by the opaque or semi-opaque portions it encounters in its passage. The image, in consequence, is either altogether obliterated, or rendered dim and indistinct. If the opaque lens be extracted, the full perception of light returns; but one prin cipal instrument for producing the convergence of the rays being removed, the image, instead of being formed on the retina, is formed considerably behind it, and the rays being received in their unconverged state on it, produce no regular picture, and therefore no distinct vision. But if we give to the rays, before their entry into the eye, a certain proper degree of convergence, by the application of a convex lens, so as to render the remaining lenses capable of finally effecting their exact convergence on the retina, restoration of distinct vision is the immediate result, This is the reason why persons who have undergone the operation for the cataract, (which consists in either totally removing, or in putting out of the way, an opaque crystalline,) wear spectacles of comparatively very short focus. Such glasses perform the office of an artificial crystalline.

A similar imperfection of vision to that produced by the removal of the crystalline, is the ordinary effect of old age, and its remedy is the same. In aged persons, the exterior transparent surface of the eye, called the cornea, loses somewhat of its convexity, and becomes flatter. The power of the eye is therefore diminished, and a perfect image can no longer be formed on the retina. The deficient power is however supplied by a convex lens, and vision rendered perfect, or materially improved.

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Short-sighted persons have their eyes too convex, and this defect is, like the other, remediable by the use of proper lenses of an opposite character. There are cases, though rare, in which the cornea becomes so very prominent as to render it impossible to apply conveniently a lens sufficiently concave to counteract its action. Such cases would be accompanied with irremediable blindness, but for that happy boldness, justifiable only by the certainty of our knowledge of the true nature and laws of vision, which in such a case has suggested the opening of the eye, and removal of the crystalline lens, though in a perfectly sound state.

Malconformations also of the cornea are much more common than is generally supposed, and few eyes are, in fact, free rom them. They may be detected by

closing one eye, and directing the other to a very narrow, well-defined luminous object, not too bright; such as the horns of the moon, when a slender crescent, only two or three days old. By turning the head about in various directions, the line will be doubled, tripled, and variously distorted, according to the peculiar conformation of the refracting surfaces of the eye, which causes the appearances.

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As we have two eyes, and a separate image of every external object is formed in each, it may be asked, why do we not see double? It may be answered, that it is an act of the judgment; two images are undoubtedly presented to our sight, but habit has taught us to bring them into one. Infants undoubtedly see double; present anything to a young child, and it invariably, at its first attempt to seize the object, stretches out its hand too much to the right or the left of the thing offered. Those who have an eye distorted by a blow see double, till habit has taught them anew to bring both objects to the same focus, though the distortion of the optic axis still subsists; and the double sight of men in a state of intoxication has become a proverb.

That a separate image is formed in each eye any one may prove by the following simple experiment. Place a wafer, or a candle on a table, and looking at it with both eyes, only one wafer or one flame is seen; but if while looking at it, one of the eyes be pressed with the finger so as forcibly to throw the image on another part of the retina of that eye, double vision is immediately produced, and two wafers or two flames become distinctly visible, which appear to recede from each other as the pressure is stronger, and approach, and finally blend into one, as it is lessened.

Dr. Wollaston has supposed that a physiological cause has some share in producing the effect of single vision; he concludes, that a semi-decussation of the optic nerves takes place immediately on their quitting the brain, half of each nerve going to each eye, the right half of each retina consisting wholly of fibres of one nerve, and the left wholly of the other, so that all images of objects out of the optic axes, are perceived by one and the same nerve in both eyes, and thus a powerful sympathy and perfect unison are kept up between them, independent of the mere influence of habit. Immediately in the optic axis, it is supposed, that the fibres of both nerves are commingled, and this may account for the greater acuteness and certainty of vision in this part of the eye.

This, though an ingenious theory, has not yet been proved by anatomists.

There is one remarkable fact which ought not to escape mention: it is, that the spot, at which the optic nerve enters the eye, is totally insensible to the stimulus of light, for which reason it is called the punctum сасит. The reason is obvious: at this point the nerve is not yet divided into those almost infinitely minute fibres, which are fine enough to be either thrown into tremors, or otherwise changed in their mechanical, chemical, or other state, by a stimulus so delicate as the rays of light. The effect, however, is curious and striking. On a sheet of black paper, or other dark ground, place two white wafers, having their centres three inches distant. Vertically above that to the left, hold the right eye, at twelve inches from it, and so, that when looking down on it, the line joining the two eyes shall be parallel to that joining the centre of the wafers. In this situation, closing the left eye, and looking full with the right at the wafer perpendicularly below it, this only is seen, the other being completely invisible. But if removed ever so little from its place, either to the right or left, above or below, it becomes immediately visible, and starts, as it were, into existence.

meetings in this country, was Dr. Brewster, the boast of modern Athens. That highly gifted philosopher was anxious that his native land should not fall behind in the use of means to promote the best interests of science. Accordingly, some months ago, he and other friends of science arranged to hold their first meeting in the ancient city of York, as being the most central situation.

"Pratinus Eboraci veteris surgebat imago; Mænia cum tectis, turres, ac templa." First Day, Monday, September 26. The former part of this day was distinguished by the influx of numerous strangers, several of whom were illustrious for their scientific discoveries. In the evening, the splendid suite of rooms in the Yorkshire Museum, were thrown open for a scientific

conversazione. The rooms were illuminated with gas, whose brilliant light presented to view every object which they contained. Groupes of elegant females, attended by their beaux, paraded promiscuously. The charms of beauty, and the stores of philosophy, which united to attract the attention of the most careless observer, could not fail to prove both interesting and pleasing.

The vestibule of the Museum, through which the company passed, was ornamented with specimens of some of the most beautiful tropical plants, from the stores of John Smith, Esq.,Huggate, York; and they added much to the diversified beauty of the scene. Amongst the specimens were, the musa paradisiaca, ENCE, HELD AT YORK, SEPTEMBER 26, (the plantain,) musa sapientum, (the bana

FIRST MEETING OF THE BRITISH ASSOCIA-
TION FOR THE ADVANCEMENT OF SCI-

1831.

NO. I.

"Distat opus nostrum, sed fratribus exit ab iisdem Artis et ingenuæ cultor uterque sumus." OVID.

THE month of September saw the termina-
tion of the commonwealth in England, and
the commencement of republicanism in
France. The same month has also seen
philosophy inviting her sons to relinquish
the boisterous element of party politics, and
accompany her to her calm retreat at York.
Ancient Ebor has had a fresh laurel added
to his brow by the circumstance –
-a chaste
handmaid to administer to his wants in his
declining years.

The first idea of a British association for the advancement of science, was suggested by those of a similar nature which have been held for the last nine years upon the continent. The first meeting was at Leipsic; others afterwards at Halle, Wurtzburg, Frankfort, Dresden, Munich, and Berlin; where the celebrated Humboldt, in September, 1830, presided over nearly 500 of the most distinguished individuals of the age. The individual who first suggested similar 2D. SERIES, NO. 13.- VOL. II.

na,) musa rosacea, (the date palm,) dracæna ferrea, (the dragon tree,) all natives of the Indies. Their verdant hues were a delightful contrast with the sombre appearance of the fossil specimens.

About nine in the evening, tea and coffee were served up in the theatre of the Museum. At ten, Mr. Phillips, the secretary of the Yorkshire Philosophical Society, delivered an animated lecture on the geology of Yorkshire, got up on the spur of the moment, without any premeditation ; a demonstrative proof of the secretary's intimate acquaintance with the subject. The lecture was illustrated by various specimens of fossils and minerals. Among the number, was a fossil animal, dug out of a coal-pit in the West Riding. It has been shewn to different geologists, both in England and France, but they by no means agree in their opinion, whether the animal's element had been land or water. The majority are inclined to think that it might have been a fish. In the course of the lecture, Mr. P. took the opportunity of expressing his conviction, that Great Britain had formerly

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been covered with the ocean; and that the science of geology was making such rapid advances, that, in a few years, geologists would be enabled to lay down a map of the different strata, with their ages, and the periods of their formation.

The company seemed highly delighted, both with the lecture and the lecturer, and separated about eleven o'clock. Thus ended the first day's meeting, which may be considered as merely introductory.

The following is a correct list of the visiters who attended on the occasion; though many of them could not enjoy the pleasure of spending the whole week in York :

Viscount Milton, president, Y.P.S.; Rev. W.V. Harcourt, acting vice-president; Viscount Morpeth; Lord Dundas; Hons. William and Charles Howard; Hon. and Rev. H. Howard; Sir Philip G. Egerton, Bart.; Archdeacons Harcourt and Wrangham; Sir T. M. Brisbane, K. C. B.; Hon. Mr. Justice Park; Dr. Brewster; R. J. Murchison, pres. geol. soc.; Dr. Daubeny, prof. of chim., Oxford; J. Robison, sec. roy. soc., Edinburgh; Hon. Withum Lurtington; J. D. Forbes; T. Allan; J. Astley; R. Allan; J. F. Johnson, from Edinburgh; Rev. Dr. Lloyd, Provost of Trin. Col. Dublin; J. Dalton, F.R.S., Manchester; J. C. Pritchard, M.D. Bristol; J. Booth, M.D. Birmingham; Rev. W. Turner; J. Adamson; William Hutton, Newcastle-upon-Tyne; John Marshall; John Marshall, jun.; and James Marshall, Headingley; Rev. William Scoresby, F. R.S.; T. Lane, M. D., Liverpool; Luke Howard, Ackworth; R. Potter, Smedley-Hall, Manchester; Rev. Jas. Hunter, F. S. A., Bath; Rev. J. Yates, London; Rev. Dr. Pearson, vice-pres. ast. soc.; W. H. Charlton, and E. Charlton, Hesleyside, Northumberland; T. Meynell, jun., Yarm; W. West; John Hey; Dr. Williamson, Leeds; Sir C.Ibbotson, Bart., Denton-park; Benj. Rotch, London; W. Gilbertson, Preston; J. Gould, geol. soc., London; R. Havell, London; J. G. N. Armitage, Huddersfield; Rev. J. Radcliffe, Oxford; J. Cooke, Doncaster; M. White, Newbury, Berks; J. Emerson, Bristol; W. Earle, London; W. H. Gilby, M. D.,Wakefield; J. Dunn, Scarborough; W.H. Dykes; J. E. Lee, Hull; H. Fate, Portsmouth; H. Warwick, M. D., Manchester; Rev. J. Drake, Kirkthorpe; W. L. Wharton, Durham; A. Strickland, Boynton; Dr. Black, Bolton; W. Allen, Peal, Lancashire; E. T. Tracy, Teddington, Gloucestershire; J. K. Watkinson, Bolton; A. Faulds, Worsbro'; W. Smith, Hackness, (author of the geological map of England ;) T. Embleton, Middleton: E. N. Alexander, F.S. A., Halifax; Sir George Cayley, Bart., Brompton; L.

Macdonald, London; Geo. Johnson, M.D., Berwick; Professor Rennie, King's College, London; H. Denny, Leeds; Dr. Travis, Malton; E. S. Cayley, Wydale; Captain Newberry, Malton; W. H. Lloyd; B. Middleton; W. Etty, R. A., Loudon; Captain Elliot, R. N.; Captain Hoppner, R.N.; H. H. Cheek, Edinburgh; Rev.T. Dury, Keighley; Dr. Ayre, Hull; F. J. Williams, Trin. Col.,Cambridge; Colonel Williamson, Shinton-hall, Lancashire; Rev. Dr. Geldart, KirkDeighton; Dr. J. W. Geldart, Professor of Civil Law, Cambridge; F. II. Fawkes, Farnley; R. Northern, Hull; T. Longman, London; Rev. T. Rankin, Huggate; Rev. B. Bailey, Travancore; Rev. W. Jowett, London, &c.

It must, at the same time, be understood, that the majority of the nobility, clergy, and gentry, in and near York, attended; some occasionally, and others the whole of the meetings. His Grace the Archbishop of York honoured some of the meetings with his presence, and occasionally entertained most of the scientific visiters, with his accustomed hospitality, at Bishopthorpe. Huggate. T. R.

AN AMERICAN SCENE, FROM AUDUBON'S AMERICAN ORNITHOLOGY.

As the author of this interesting volume is well known to many in England and Scotland, the following romantic narrative will probably prove highly gratifying to such of his friends as have not had an opportunity of perusing his book.

On my return from the Upper Mississippi, I found myself obliged to cross one of the wide prairies, which, in that portion of the United States, vary the appearance of the country. The weather was fine; all around me was as fresh and blooming as if it had just issued from the bosom of nature. My knapsack, my gun, and my dog, were all I had for baggage and company. But, although well moccassined, I moved slowly along, attracted by the brilliancy of the flowers, and the gambols of the fawns around their dams, to all appearance as thoughtless of danger as I felt myself.

My march was of long duration: I saw the sun sinking beneath the horizon long before I could perceive any appearance of woodland, and nothing in the shape of man had I met with that day. The track which I followed was only an old Indian trace, and, as darkness overshaded the prairie, ĺ felt some desire to reach at least a copse, in which I might lie down to rest. The nighthawks were skimming over and around me,

attracted by the buzzing wings of the beetles, which form their food; and the distant howling of wolves, gave me some hope that I should soon arrive at the skirts of some woodland.

I did so, and almost at the same instant a fire-light attracting my eye, I moved towards it, full of confidence that it proceeded from the camp of some wandering Indians. I was mistaken:-I discovered by its glare that it was from the hearth of a small log cabin, and that a tall figure passed and repassed between it and me, as if busily engaged in household arrangements.

I reached the spot, and, presenting myself at the door, asked the tall figure, which proved to be a woman, if I might take shelter under her roof for the night. Her voice was gruff, and her attire negligently thrown about her. She answered in the affirmative. I walked in, took a wooden stool, and quietly seated myself by the fire. The next object that attracted my notice was a finely-formed young Indian, resting his head between his hands, with his elbows on his knees. A long bow rested against the log wall near him, while a quantity of arrows and two or three racoon skins lay at his feet. He moved not; he, apparently, breathed not. Accustomed to the habits of the Indians, and knowing that they pay little attention to the approach of civilized strangers, (a circumstance which, in some countries, is considered as evincing the apathy of their character,) I addressed him in French, a language not unfrequently partially known to the people in that neighbourhood. He raised his head, pointed to one of his eyes with his finger, and gave me a significant glance with the other. His face was covered with blood. The fact was, that, an hour before this, as he was in the act of discharging an arrow at a racoon in the top of a tree, the arrow had split upon the cord, and sprung back with such violence into his right eye as to destroy it for ever.

Feeling hungry, I inquired what sort of fare I might expect. Such a thing as a bed was not to be seen, but many large untanned bear and buffalo hides lay piled in a corner. I drew a fine time-piece from my breast, and told the woman that it was late, and that I was fatigued. She had espied my watch, the richness of which seemed to operate upon her feelings with electric quickness. She told me that there was plenty of venison and jerked buffalo meat, and that on removing the ashes I should find a cake. But my watch had struck her fancy, and her curiosity had to be gratified by an immediate sight of it. I took off the gold chain that secured it, from around my neck,

and presented it to her. She was all ecstacy, spoke of its beauty, asked me its value, and put the chain round her brawny neck, saying how happy the possession of such a watch would make her. Thoughtless, and, as I fancied myself in so retired a spot, secure, I paid little attention to her talk or her movements. I helped my dog to a good supper of venison, and was not long in satisfying the demands of my own appetite.

The Indian rose from his seat, as if in extreme suffering. He passed and repassed me several times, and once pinched me on the side so violently, that the pain nearly brought forth an exclamation of anger. I looked at him. His eye met mine; but his look was so forbidding, that it struck a chill into the more nervous part of my system. He again seated himself, drew his butcherknife from its greasy scabbard, examined its edge, as I would do that of a razor suspected dull, replaced it, and again taking his tomahawk from his back, filled the pipe of it with tobacco, and sent me expressive glances whenever our hostess chanced to have her back towards us.

Never, until that moment, had my senses been awakened to the danger which I now suspected to be about me. I returned glance for glance, to my companion, and rested well assured that, whatever enemies I might have, he was not of their number.

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I asked the woman for my watch, wound up, and, under pretence of wishing to see how the weather might probably be on the morrow, took up my gun, and walked out of the cabin. I slipped a ball into each barrel, scraped the edges of my flints, renewed the primings, and, returning to the hut, gave a favourable account of my observations. I took a few bear-skins, made a pallet of them, and calling my faithful dog to my side, lay down, with my gun close to my body, and in a few minutes was, to all appearance, fast asleep.

A short time had elapsed, when some voices were heard; and from the corner of my eyes I saw two athletic youths making their entrance, bearing a dead stag on a pole. They disposed of their burden, and, asking for whiskey, helped themselves freely to it. Observing me and the wounded Indian, they asked who I was, and why the devil that rascal (meaning the Indian, who, they knew, understood not a word of English) was in the house. The mother-for so she proved to be-bade them speak less loudly, made mention of my watch, and took them to a corner, where a conversation took place, the purport of which it required little shrewdness in me to guess. I tapped my dog gently. He moved his tail, and

with indescribable pleasure I saw his fine eyes alternately fixed on me and raised towards the trio in the corner. I felt that he perceived danger in my situation. The Indian exchanged a last glance with me.

The lads had eaten and drunk themselves into such condition, that I already looked upon them as hors de combat; and the frequent visits of the whiskey bottle to the ugly mouth of their dam, I hoped would soon reduce her to a like state. Judge of my astonishment, reader, when I saw this incarnate fiend take a large carving-knife, and go to the grind stone, to whet its edge. I saw her pour the water on the turning machine, and watched her working away with the dangerous instrument, until the cold sweat covered every part of my body, in despite of my determination to defend myself to the last. Her task finished, she walked to her reeling sons, and said, "There, that'll soon settle him! Boys, kill you and then for the watch."

I turned, cocked my gun-locks silently, touched my faithful companion, and lay ready to start up and shoot the first who might attempt my life. The moment was fast approaching, and that night might have been my last in this world, had not Providence made preparations for my rescue. All was ready. The infernal hag was advancing slowly, probably contemplating the best way of despatching me, whilst her sons should be engaged with the Indian. I was several times on the eve of rising, and shooting her on the spot :-but she was not to be punished thus. The door was suddenly opened, and there entered two stout travellers, each with a long rifle on his shoulder. I bounced up on my feet, and, making them most heartily welcome, told them how well it was for me that they should have arrived at that moment. The tale was told in a minute. The drunken sons were secured; and the woman, in spite of her defence and vociferations, shared the same fate. The Indian fairly danced with joy, and gave us to understand that, as he could not sleep for pain, he would watch over us. suppose that we slept much less than we talked. The two strangers gave me an account of their once having been themselves in a somewhat similar situation. Day came, fair and rosy, and with it the punishment of our captives.

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They were now quite sobered. Their feet were unbound, but their arms were still securely tied. We marched them into the woods off the road, and having used them as Regulators were wont to use such delinquents, we set fire to the cabin, gave all the skins and implements to the young Indian

warrior, and proceeded, well pleased, towards the settlements.

During upwards of twenty-five years, when my wanderings extended to all parts of our country, this was the only time at which my life was in danger from my fellowcreatures. Indeed, so little risk do travellers run in the United States, that no one born there ever dreams of any to be encountered on the road; and I can only account for this occurrence, by supposing that the inhabitants of the cabin were not Americans.

Will you believe, good-natured reader, that not many miles from the place where this adventure happened, and where, fifteen years ago, no habitation belonging to civilized man was expected, and very few ever seen, large roads are now laid out, cultivation has converted the woods into fertile fields, taverns have been erected, and much of what we Americans call comfort is to be met with. So fast does improvement proceed in our abundant and free country.

This enthusiastic naturalist, the narrator of this adventure, is gone again to the woods. He left Edinburgh, in April, 1831, and, after visiting Paris, intended proceeding to New Orleans, in August. It is his purpose to spend eighteen months or two years in exploring the western side of the valley of the Mississippi, up towards the Rocky Mountains. Should he survive, he intends returning to Edinburgh, and spending the rest of his days in arranging his collection, and publishing a continuation of his Ornithological Biography.

METEOROLOGICAL OBSERVATIONS.

THE mean temperature, from November 1st to 19th, 1831, was 42 degress of Fahrenheit's thermometer. The maximum, which was 55 degrees, took place on the 1st, when the direction of the wind was southerly; the minimum, which was 30 degrees, took place on the 18th, when the direction of the wind was north-westerly. The range of the thermometer during the nineteen days was 25 degrees; and the prevailing wind west. During the above period, the direction of the wind has been westerly eleven days; north-westerly, four; southwesterly, three; and southerly, one.

The morning of the 9th was rather foggy; but towards noon the fog dispersed, and the afternoon was peculiarly fine; and, as the sun descended towards the horizon, the appearance of the webs of the gossamerspider on the herbage was particularly interesting. As the observer looked towards the sun, the surface of the verdant carpet at his feet presented a luminous appearance, in consequence of the reflection of

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