let in the more of its rays. The third coat is only a fine expansion of the optic nerve L, which spreads like net-work all over the inside of the choroides, and is therefore called the retina; upon which are painted (as it were) the images of all visible objects by the rays of light, which either flow to, or are reflected from them. Under the cornea is a fine transparent fluid like water, which is therefore called the aqueous humour. It gives a protuberant figure to the cornea, fills the two cavities'm m and nn, which communicate by the pupil P, and has the same limpidity, specific gravity, and refractive power as water. At the back of this lies the crystalline humour, I I, which is shaped like a double convex glass; and is a little more convex on the back than the fore part. It converges the rays, which pass through it from every visible object to its focus at the bottom of the eye. This humour is transparent like crystal, is much of the consistence of hard jelly, and exceeds the specific gravity of water in the proportion of eleven to ten. It is enclosed in a fine transparent membrane, from which radial fibres o o, called the ligamentum ciliare, all around its edge join to the circumference of the iris. These fibres have the power of contracting and dilating occasionally, by which means they alter the shape or convexity of the crystalline humour, and also shift it a little backward in the eye, so as to adapt its focal distance to the bottom of the eye to the different distances of objects; without which provision, we could only see those objects distinctly, that were all at one distance from the eye. At the back of the crystalline, lies the vitreous humour, K K, which is transparent, like glass, and is largest of all in quantity, filling the whole orb of the eye, and giving it a globular shape. It is much of the consistence of the white of an egg, and very little exceeds the specific gravity and refractive power of water. As every point of an object, A, B, C, sends out rays in all directions, some rays from every point on the side next the eye will fall upon the cornea between E and F; and by passing on through the humours and pupil of the eye, they will be converged to as many points on the retina or bottom of the eye, and will thereon form a distinct inverted picture c, b, a, of the object. Thus, the pencil of rays, q, r, s, that flow from the point A of the object, will be converged to the point a on the retina; those from the point B will be converged to the point 6; those from the point C will be converged to the point c; and so of all the intermediate points: by which means the whole image a, b, c, is rmed, and the object made visible. The different organs which surround the ball of the eye, and which are provided for the purpose of motion, of defence, and of lubrication, were next described. The six muscles belonging to the globe itself, namely, four straight and two oblique muscles; the structure of the eyelids, the cartilage which preserves their shape, the muscles by which they are moved, the situation of the lachrymal gland and its ducts; the mode in which the tears are uniformly spread over the surface of the cornea, in which they are directed towards the inner corner of the eye, by the closing of the eye-lids, absorbed by the puncta lachrymal, i, a, and conducted into the lachrymal, s, a, c, which opens into the cavity of the nostrils, were severally pointed out and fully examined, with all the minute correctness which distinguishes this excellent physiologist. LONDON MECHANICS' INSTITUTION. WE have much pleasure in recording the name of Wilberforce, in the list of generous contributors to the progress of intellectual improvement amongst the lower classes. The following letter to the president of the parent Metropolitan Mechanics' Institution, will, however, best explain the feelings of the above practical christian and real philanthrophist. SIRI must begin my letter by doing myself the justice to assure you, that my not having had the honour of being among the earliest of your supporters, arose only from my not hearing of the intended Institution till long after it had been formed. This arose from my having been compelled, from two successive illnesses, to absent myself from London and its neighbourhood early in the spring of last year; ever since which time, I have been living in retirement in obedience to my medical advisers, with a view to the reestablishment of my health. I had understood that the just support which your excellent Institution had obtained, was such as to render any further contributions needless. This consideration only prevented my sending in my little aid, which not being needed for the object in view, might justly subject me to the imputation of vain-gloriously wishing to be deemed a supporter of a plan which had already been completely established. But I happened to hear the other day that, in the further prosecution of the design, expenses will be incurred, for which further subscriptions are necessary. I therefore gladly transmit my little contribution, begging you to believe that it is a very inadequate measure of the esteem I entertain for the Institution itself, or of my wish that it may be productive of all the benefits OXFORD CASTLE. which its warmest friends can venture to anticipate. I cannot conclude without remarking, that it adds to my satisfaction in relation to this business, that, if I mistake not, its chief projector is a countryman of mine nay, I believe you are also a member of a family whose friendly support I always felt myself honoured by enjoying, during the whole period of my being a member for the county of York. 329 of a mummy from the isle of Teneriffe ; with respect to the constancy of those properties which render hair important as a hygrometric substance. For this purpose, hygrometers constructed according to Saussure's principles were made; one with a recent hair, and the other with hair from the mummy. The ancient hairs were not so strong as the other, or of sufficient length alone; but the latter objection was obviated by tying four together. The results of the experiments were, that in both instruments the interval between the extremes of the moisture and dryness of the chamber, (about 250,) was passed in three minutes; that the indications, like those of the thermometer, &c., were rapid on leaving the first term, and became slower on approaching the second; that the hygrometric quality of the Guanche hair, is sensibly the same as that of the recent hair. Topography. I remain, dear sir, DR. BIRKBECK. PERMANENCY OF HUMAN HAIR.' M. PICTET has lately made a comparison between a portion of recent human hair, and another portion from the head THIS relic of feudal domination stands on the west side of the town of Oxford, a small distance east of the river Isis. It was built in the year 1071, by Robert d'Oilley, a Norman, who came over with William the conqueror; and who, for his services, was rewarded by that prince with considerable grants of land in this county. In the reign of king Stephen, the castle was delivered up to the empress Matilda, who kept the Easter festival in the city with great solemnity. The next year, Stephen having taken the town by a fortunate act of temerity, laid siege to the castle, where the empress resided; which, with the tower that covered one side of it, was considered impregnable. The king threw up entrenchments round the fortress, and cut off all supplies of provision. Matilda, after having, by her exhortations and example, animated the garrison to make a much more vigorous. defence than could be expected, at length, reduced to the utmost extremity for want of every necessary, made a sort of Bonapartean exit: she went privately out of the castle by night, without the knowledge of the garrison, accompanied only by three trusty attendants, and being conducted by a soldier of Stephen's army, whom she had gained by presents, crossed over the Thames, which was frozen so hard as to bear, and passing through the midst of the enemy's army which guarded the opposite side of the river, after great hazard and fatigue reached Abingdon; having walked six miles through a deep snow. It is said she and her attendants were clothed in white, to render themselves less distinguishable in their flight. The garrison, as soon as they were acquainted with her departure, surrendered on terms. Grose says, little of the castle was remaining in the year 1751 except the tower, which then served for a county prison. Near it is a small chapel, built by contribution, for the use of the prisoners. The wall on the left is part of the ancient structure, and is ten feet thick. Beneath the moat in the castleyard are the remains of the ancient sessions-house, in which was held, in 1577, what is styled the Black Assize, on account of an infectious distemper brought by the prisoners, whereby the lieutenant of the county, two knights, eighty squires and justices of the peace, besides almost all the gentlemen of the grand jury, died. Above an hundred scholars, besides townsmen, were attacked by the same disorder; which was attended with a kind of phrensy, so that those affected with it ran wildly through the streets, assaulting every one they met, their go vernors not excepted. EGYPTIAN MILL. MR. KENT, of Carpenter's Hall, has favoured us with a sketch of an ancient corn mill, which is now preserved in the Missionary Museum. This curious relic of Egyptian domestic economy exactly resembles the ancient military mill, and consists of two stones, the outer of which is one foot nine inches in diameter, by seven inches in height, while the inner or movable one is about two-thirds of that size. The upper stone is turned by a strong pin furnished with a ball at top, and the grain is introduced at the central aperture, so that the rotation of the stone upon its axis gradually carries it towards the opening at the side. THE POCKET ANNUAL REGISTER, OR THE "THE experience of more than half a century has confirmed the value of those records of events, called Annual Registers, and they are now to be found in every good library; there is, however, a class of persons to whom their bulk or price may not be suitable, and to such we would recommend this really clever little volume. It is a faithful epitome of the events of the year, executed, with good taste and great discrimination; and contains a digest of the Foreign and Domestic History of the Year, the Proceedings in Parliament, Public Documents, State Papers, a Chronicle of Occurrences, and Law Proceedings. The volume also contains memoirs of nearly fifty distinguished persons who died during the last year. Miscellanies of science, art, and literature, extracts from new books, characters of individuals, select poetry, &c." Having perused this little volume with considerable attention, we feel justified in speaking of it as a peculiarly useful publication. The plan on which it is executed is sufficiently comprehensive to embrace all the information that is generally wanted, in the provinces of intelligence on which it professes to enlighten its readers; and the execution, in the essential points of brevity and explicitness, is equal to the excellence of the design. A more useful, interesting, or better arranged pocket volume we never met with, SPECULUM CÆLORUM FOR THE ENSUING WEEK. Conjunctions.-On the morning of the 23d, at ten, the Moon and Jupiter will be in conjunction in 7 degrees 42 minutes of Leo, the planet being at this time about 3 degrees to the south of the Moon's centre. On the evening of the 26th, at half past ten, the heliocentric and geocentric longitudes of Mars will coincide in 5 de grees 18 minutes of Gemini, the planet and Sun being in conjunction. Station of Mercury.-This phenomenon will take place on the 26th, in 18 degrees 16 minutes of Taurus. At this time the planet's elongation from the Sun will be 16 degrees 36 minutes to the west. Apsides of the Moon and Mercury. On the 22d, Mercury will be in the higher apsis of his orbit, or aphelion, i. e. that point which is most distant from the Sun. This phenomenou always happens when the heliocentric longitude of the planet is GEOLOGY. about 44 degrees; . e. in about 14 degrees of Taurus. The Moon will be in her lower apsis, or perigee, on the 28th. This point of the lunar orbit is that which is nearest to the Earth's centre. Other Phenomena.-Jupiter sets soon after midnight, and is situated 47 minutes to the north of the ecliptic. Herschel will be above the horizon almost the whole night. His geocentric situation is in 19 degrees of Capricorn, with 27 minutes of north latitude. The angular distances of Saturn, Mars, and Mercury, will be too small to admit of their being readily observed without the aid of a telescope. GEOLOGY. Alluvial Lands-Formation of Soils. ALLUVIAL lands consist of deposits of matter in vallies, worn down from neighbouring rocks and mountains. Among these lands or formations, are gravel, loam, clay, sand, and marl. They owe their origin to the agency of the ocean, of rivers, lakes, and springs; and when they contain the remains of elephants, and rhinoceri, they are called diluvian, as they seem to have been formed at the time of the deluge; but when of more recent origin, as are daily formed on the face of the earth, they are called post-diluvian. All being the work of running waters, or inundations, the earthy matters, such as sand and argil, constitute the principal mass; rocks decomposed by the action of the elements become pulverized, and are mixed by the waters with stones, pebbles, bones, and shells, and are thus deposited in cavities, by which the soil has been extended, and the basin of the ocean contracted. This effect has been progressive, and to this moment continues, thus accounting for the changes in the face of countries, and rendering itself observable in almost every direction. Veins of metallic ores, which once intersected mountains, have been worn down by this levelling process, and have been found in the alluvial deposits of primary and transition rocks. Thus the banks and sands of rivulets in Cornwall abound with tin stone or ore of tin. Gold and diamonds are found in similar situations; and it is more than probable that the gold and diamond rivers of the Brazils had a like origin. In alluvial lands likewise occur beds of peat and wood coal. Connected with this portion of our subject is the formation of Soils, which has been so well illustrated by that distinguished agricultural chemist sir Humphry Davy. Soils are formed of the earths, 331 silica, lime, alumina, magnésia," and of the oxides of iron and manganesum, animal and vegetable matters in a state of decomposition, and saline, acid, or alkaline combinations. They appear to have been originally produced by decomposed rocks and strata. The atmosphere being filled with the seeds of lichens and mosses, is constantly depositing them on thin layers of earth formed on the surfaces of rocks; these seeds vegetate, and their death, decomposition, and decay, form organizable matter which mixes with the earthy materials of the rock. At length more perfect plants flourish there, the decomposition of the rock still continues, and poor soils, formed of decomposed granite and sandstone rocks, thus remain for ages with a thin covering of vegetation. Limestone, chalks, and basalts, when decomposed, form rich soils; and in chalky districts, consisting of vegetable mould, the surface a few inches thick is often covered with perennial grasses, while the base is a stupendous and barren mass. This is peculiarly exemplified in the immense quarries of limestone at Dorking, in Surrey, whence lime equal in purity and strength to any in the kingdom is produced. This unceasing system of fecundation is a moral lesson to the pride of man! Thus church-yards are known to form the most fertile soils; and in the neighbourhood of Mortlake, there is a humiliating proof of this assertion, in the burial-place of several archbishops of Canterbury, now being celebrated as the most productive garden in the vicinity of the metropolis. Even such is time; which takes in truth To the Editor of the Circulator. IN your very entertaining publication (No. X.) the public are favoured with the portraiture and character of a very singular female; one whose services to her country were rewarded by its protection, and whose extraordinary length of years, dexterity, and retention of faculty had been for half a century and upwards the admiration of all within the sphere of her existence. Permit me, sir, to follow up your narration with a description of another female who, although beneath the former in length of years, was far above her in military achievements. She was what the poet describes Omphale to be to Hercules: "Clad in the lion's skin. she placed her lord To turn the wheel, and spin the silken cord, Then drew the mighty weapon from his arm, Forgot her sex, and spread the rude alarm." She was in valour greater than the celebrated Hannah Snell, or the sister of the brave captain Chamberlain, who fought valiantly in man's clothing six hours against the French on board a fire-ship under the command of her brother. She was-but let her own narrative in a petition to the secretary at war describe her heroic deeds, and patient endurance: THE HEROISM of Elizabeth HOPKINS. The memorial of Elizabeth Hopkins, wife of Jeremiah Hopkins, sergeant of the 104th regiment of foot: Most humbly showeth, that she was born of British parents at Philadelphia, in the year 1741; has her husband, six sons and a son in law serving his majesty in the 104th; and during the course of her life, from her zeal and attachment to her king and country, she has encountered more hardships than commonly fall to the lot of her sex. That in the year 1770 being with her first husband,(John Jasper,) a sergeant of marines on board the brig Stanley, she was wounded in her left leg in an engagement with three French vessels, when she was actually working at the guns. That the marines having been landed at Cape May, in America, her husband was taken prisoner by a captain Plinket of the rebel army, near Mud-Fort Nied, and sentenced to suffer 'death; that by her means he was enabled to escape with twenty-two American deserters, to whom she served arms and ammunition; and, on their way to join the army, their party was attacked by the enemy's light horse; she was fired at and wounded in her left arm; but, undismayed, took a loaded firelock, shot the rebel, and brought his horse to Philadelphia, (the head-quarters of the army,) which she was permitted to sell to one of general Howe's aide-de-camps. That after many fatigues and campaigns her husband died, and she married Samuel Woodward, a soldier in colonel Chambers's corps; was, with the troops under general Campbell, taken at Pensacola, having, however, during the siege served at the guns, and tore up her clothes to supply the want of wadding. That having been exchanged at the peace of 1783, from attachment to the royal cause she embarked on board a transport with part of Delancey's and Chambers's corps; was shipwrecked on Seal Island, in the Bay of Fundy, when near three hundred men, and numbers of women and children, were lost. That she suffered unparalleled distress; being pregnant, and with a child in her arms, remained three days on the wreck; was taken up with her husband and child by fishermen off Marble-head; and, shortly after being landed, delivered of three other dead. Lastly, that she has had the sons, two of whom are in the 104th, the honour of being the mother of twenty-two children-namely, eighteen sons and four daughters; seven of the former being alive, and three of the latter. That your memorialist humbly prays, that you may consider her as a fit object for some allowance from the compassionate fund towards her maintenance in her old age, having lost all her property, as a reward for her long and faithful services to her king, as in duty bound shall ever pray. New Brunswick, April 12, 1816. The subject of this memorial is now far advanced in years, and was about two months since hearty and well at Quebec. In consequence of her memorial she obtained a pension from our government of 100% a year. T. N. April 13th, 1825, ROYAL ACADEMY A PICTURE which excites no small share of attention in the present exhibition, is Mr. Hayter's trial of Lord Russell. This is the best work that the artist has produced, and is an admirable display of care and patience. The general arrangement and disposition of the composition are good, and the different figures possess in an eminent degree individual character and passionate expression; but the grand defect is, that the spectator upon first sight is under the necessity of inquiring for the principal figure. This partly arises from the quotation which the artist has thought proper to affix in the catalogue; the words alluded to are-" The two first witnesses having been examined, Lord Howard of Escrik was sworn." The actions of the sergeant with his hand upon a book, and of the figure intended for Lord Russell, so perfectly accord with this, that they are generally mistaken. There indeed appears to be an impropriety in bringing in the incident at all of swearing Lord Howard, at the moment that the counsel is questioning, with so much apparent vigour, the prisoner. The picture by Mr. Hilton, of Christ crowned with thorns, displays more of science in the mechanism, and of academic |