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after him. The phases, as they are termed, of this planet are shown in the diagram be

from spiracles in the body or from local agitation, form the spots of which we are speaking. The above engraving will illus-low; in which it appears, that when nearly trate our meaning.

A spectator on the earth at E, when viewing the sun under the circumstances represented above, would see a dark spot Occupying the space between the lines B and c, being a portion of the solid body of the sun, whilst the spaces between A в and CD would form the penumbra occasioned by the greater removal of the upper (and luminous) strata, than of the lower or more dense strata.

The quantity of light received from the sun, has been estimated to be equal to that of 5563 wax candles, of moderate size, if they could be placed at the distance of one foot from an observer; whilst that of the moon has been considered as only equal to the light of one candle, placed at the distance of twelve feet. Consequently, the light of the sun is more than three hundred thousand times greater

than that of the moon.

THE PLANET MERCURY.

MERCURY is a small star, emitting a very bright white light; though, by reason of his always keeping near the sun, he is seldom to be seen; and when he does make his appearance, his motions are so rapid, that he can only be discerned for a very short period. He usually rises nearly at the same time with the sun, and sets soon

the whole of his enlightened side is turned towards the earth, his diameter seems to be only half as great as when seen in the form of a half-moon; and that when he assumes

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the crescent form, his apparent diameter is increased threefold. These apparent differences in his magnitude arise from the different distances at which he is seen from the earth; that is, when he presents a full round orb to our view, he is on the further side of the sun, and consequently is at his greatest distance from us; and when he presents the crescent form, he is between the sun and us, consequently, near his least distance from us, and therefore appears so much larger; and when he presents to our view the form of a half-moon, he is at an intermediate distance.

The shortness of the periods in which this planet can be seen, and the unfavourableness of his situation for observation, has rendered the attempts of astronomers to discover spots on his surface, by which the period of rotation on his axis could be

determined, and other matters connected | of a cannon or musket ball. When it has with his physical constitution, mere sub-made its collection, it rises aloft in the air jects of conjecture; indeed, but very little to reconnoitre its hive, and returns with is known of its nature. From his nearness the rapidity of lightning." to the sun, the proportion of light and heat he receives is about seven times greater than that received on the earth's surface; the mean heat, arising only from the intensity of the sun's rays, must be above that of boiling quicksilver; and water would boil even at his poles.

INSECTS.No. XLII.

(Vision continued.)

Ir is doubtless surprising, that a spider, with eight eyes, a centipede with twenty, and a butterfly with thirty-five thousand facettes in its two eyes, can perceive only one object; yet the difficulty resembles that which arises from our own vision. Whatever solution be admitted, it is evident that many creatures can see an object, by using one eye only, sometimes better than when both are employed. The celebrated painter, Leonardo da Vinci, recommended his pupils always to look at distant objects with one eye only. And birds, particularly those that feed on insects, in looking out for their prey, most commonly turn their head on one side, so as to bring only one eye to bear on the object. The poet Rogers supposes that bees are nearsighted:

“Hark! the bee winds her small but mellow horn,

Blithe to salute the sunny smile of morn.
O'er thymy downs she bends her busy course,
And many a stream allures her to its source.
'Tis noon, 'tis night. That eye, so finely wrought
Beyond the search of sense, the soar of thought,
Nor vainly asks the scenes she left behind;
Its orb so full, its vision so confined!
Who guides the patient pilgrim to her cell?
Who bids her soul with conscious triumph swell?
With conscious truth retrace the mazy clue
Of various scents that charm'd her as she flew?
Hail! Memory, hail! thy universal reign
Guards the least link of being's glorious chain."

Authors, indeed, are by no means agreed respecting the nature and extent of vision, as is most strikingly the case in the instance of bees. "How great," exclaims the elder Huber, "is their perfection of sight! as if to compensate the defects of their hearing. The bee, from this cause, recognises its habitation amidst an apiary of numerous others resembling it, and returns in a straight line with great velocity: we must suppose that it is distinguished by marks escaping our notice. The bee departs, and flies straight to the most flowery field; and having ascertained its course, it is seen traversing it as directly as the flight

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Wildman, on the other hand, tells us that he has observed them go up and down, seeking the door of the hive, and be obliged, after alighting, to rise again, in order to find it. He considers that they see better when flying than when alighted; not, however, as Dr. Bevan remarks, because their vision is improved by the art of flying, but from objec's being placed at a greater distance, and better adapted to the focus of their eyes. The observations

of Dr. Evans corroborate those of Wildman. "We frequently observe bees," he says, "flying straight homeward through the trackless air, as if in full view of the hive; then running their heads against it, and seeming to feel their way to the door, with their antennæ, as if totally blind." The experiments of Sir L. S. Mackenzie support the same doctrine; for he remarked the imperfect vision of bees, and how much they are sometimes puzzled to find their way, if the hives were removed two or three yards from the place where they usually stood; and he found that, for the first day or so, they did not venture to fly to a distance, till they had visited and recognised neighbouring objects.

Some have gone so far as to imagine that spiders have no eyes; but this notion has been well refuted by Swammerdam. Speaking of one of the hunting spiders, (salticus scenicus,) he says: "These seize their prey by a sudden leap, and therefore nature has provided them, as well as other spiders, with eight eyes, and a most acute sight. It is more difficult to judge of this sight in spiders that make webs; for so far from taking any notice of a finger put close to their eyes, they neither express any concern at it, nor attempt to run away; whereas, let the most minute animal fall into their nets, they immediately perceive and lay hold of it. This apparent insensibility on the one hand, and readiness of perception on the other, has made some philosophers think the web-spiders had no eyes, but received information concerning their prey only by the tremulous motion of their web. When these gentlemen further consider, that what look like eyes in spiders never appear, when viewed with the microscope, of a reticular form, as is the case in the scorpion, they more roundly deny that they have any eyes. But it by no means follows, from the webspider's never leaping upon its prey, or

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from its never running to it, unless when | proper insulation of the different kinds of taken in its net, that it has no eyes; and this conclusion must appear yet weaker, on considering that eyes are as distinctly perceivable in this kind as in the jumpingspider, (salticus scenicus,) and withal are disposed in the same manner. As to the argument drawn from the parts which look like eyes in web-spiders not being formed in the netted manner as in other insects, it is equally unsatisfactory; for what difference is there between its eyes being placed singly in different parts of the surface of the body, as in the jumping-spider, and their being gathered into one net, as in other insects? Besides, the eyes of spiders thus scattered, are much larger than those which form the netted eyes in other insects; so that, every thing duly considered, there is reason to affirm, that spiders have a more perfect sight than the generality of other insects, except the dragon-fly, (libellula,) which appears to have very large and very numerous complex eyes. Thus has nature displayed her wonders, even to those little animals, which at first sight appear to many beneath their notice."

The vision of compound eyes must be imperfect and indistinct, but, at the same time, no doubt, it is amply sufficient for the wants of insects, &c. The quantity of light which enters into the interior of the eye is also very small; but the optic nerve is probably so constituted as to perceive the faintest differences in the intensity of light and colours. Of the whole light emitted or reflected by exterior objects, we ourselves receive into the eye only that portion which the pupil is capable of admitting; and yet, when the pupil is at its minimum of dilatation, as at the time of our looking at very near or brightly-illumined objects, or when we are in considerable darkness, with the pupil dilated, perhaps, to its maximum, the smallest quantity of light will be sufficient to enable us to distinguish the general forms of bodies. A light of moderate intensity, with a mean degree of dilatation of the pupil, seems best suited to the degree of perceptibility of our sense of vision; for, when the pupil is widely dilated, as by means of bella-donna, objects at other times moderately bright then become dazzling. As soon as the general sensation of light exists, the local diversities of clear, dark, and coloured parts in bodies will likewise be perceived, provided only those conditions are present which are required for the

It would be wrong to dismiss the subject of insect-vision without glancing at a kind of auxiliary eyes, with which a large portion of them are gifted; we mean those pellucid spots often to be found on the posterior part of the front of these animals, or upon the vertex, frequently arranged in a triangle. These, Linnæus, from regarding them as a kind of coronet, called stemmata. Swammerdam and Reaumur were aware that they were real eyes. The former found that there are nerves which diverge to them, though they are not easily traced, and that they have a cornea; and the latter has supposed that the compound eyes and these simple ones have, the one the power of magnifying objects much, the other but little; so that the former are for surveying things that are distant, and the latter those that are near. The same author relates some experiments that he tried with the common hive-bee, by which he ascertained, that the stemmata, as well as the compound eyes, are the organs of vision. He first smeared the latter over with paint, and the animals, instead of making for their hive, rose in the air till he lost sight of them. He next did the same with the former, and placing the bees whose stemmata he had painted within a few paces of their hive, they flew about on all sides among the neighbouring plants, but never far he did not observe that these ever rose in the air like the others. From this experiment it seems as if the compound eyes were for horizontal sight, and the stemmata for vertical.

Here then let us pause, admiring and adoring the goodness of the beneficent Creator, who, though he has not given to insects moveable eyes, has compensated it to them by the variety and complex structure of their organs of vision. Where we have only two points of sight, they have more than as many myriads.

SIN AND GRACE,

tions of sin, so it is hazardous to make As it is dangerous to make false definifalse definitions of grace.-Brooks.

JOHN DAVIS, 56, Paternoster Row, London.
Price d. each, or in Monthly Parts, containing Five
Numbers in a Cover, 3d.

W. TYLER, Printer, Bolt-court, Fleet-street.

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THE MAMERTINE PRISON.

*

AMONG the ancient structures of Rome, the Mamertine prison claims particular notice, it being considered the oldest building in the city. This prison derives its name from Ancus Martius, the fourth king of Rome. Servius Tullius, the sixth king of Rome, added a lower cell, which was called the Tullianum. Sir William Gell, however, is at issue with the modern antiquaries of Rome, and is of opinion that it was not constructed by Tullius. This unquestionable monument of ancient Rome is situated behind the arch of Septimius Severus, and on the declivity of the Capitoline-hill, not far from the church of S. Nicola, in Carcere. By the aid of torches, the visitor descends under the little church of S. Guiseppe de Falegnami, (built in 1539,) by some modern steps, to the upper compartment, which is now formed Mamers, in the Oscan language, is Mars; as Mamercus, or Mamertinus, answers to the adjective Martius.-Burgess's Antiquities of Rome, vol. i.

p. 342.

VOL. III.

into an oratory. It is constructed of large masses of peperine stone, probably so called from the town of Piperno, the ancient Privernum, where it is found in great abundance, or from the black spots on it resembling pepper. These stones are put together without cement. The upper cell is about twenty-seven feet by nineteen feet and a half, and nearly fourteen feet in height, and has evidently been hewn out of the solid rock. Descending by a few steps more, we arrive at the lower cell, which is only about six feet and a half in height, and nineteen feet by nine. Sir William Gell considers it to be the more ancient, because it supports the superstructure. It is formed, he states, by three courses of approaching stones laid horizontally, and not on the principle of an arch. "They are strangely united by cramps of iron; so that they are together as one flat stone, lightened by a slight curvature below, and, perhaps, in a great measure depending for support on the weight of the walls of the upper structure.'

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Through the circular aperture, communicating with the upper chamber, it appears that prisoners who were condemned to be strangled or to die of hunger, were thrust down into this lower cell. Here, to omit the names of other prisoners of note, Jugurtha was suffered to die of hunger.

Numbers of devotees are continually kneeling before the lower prison, where tradition states that the apostles Peter and Paul were confined by order of Nero; and where the fountain or well of water miraculously appeared for Peter to baptize his jailer, Processus, and Martinianus, and forty-seven companions. Nay, the very pillar, to which the apostle Peter is said to have been bound, is now shown to the credulous multitude. Saint Paul's first confinement at Rome is alluded to in Acts xxviii. 16; his second epistle to Timothy has several references to his second imprisonment in that city, where ecclesiastical history attests that both these apostles suffered martyrdom, a. D. 65. Numerous excavations have of late years been made throughout Rome, which are still in progress; the results have been the bringing to light of many important remains of ancient art. The population of the modern city has varied considerably at different times; in 1832 it contained 151,000 perThe population is kept up by the influx of strangers; for the deaths exceed the births, in the proportion of 5100 to 4725 per annum. The paupers vary in number from 15,000 to 30,000.-From Finden's "Landscape Illustrations.”*

sons.

PAPAL EDIFICES.

MR. FOSTER eloquently observes respecting the buildings erected by the romanists:

Think of the incalculable cost of ecclesiastical structures, the temples of idolatry, as in truth they may be adjudged to have been. One of the most striking situations for a religious and reflective protestant is, that of passing some solitary hour under the lofty vault, among the superb arches and columns, of one of the most splendid of these edifices remaining at this day in our own country. If he has sensibility and taste, the magnificence, the graceful union, of so many diverse inventions of art, the whole mighty creation of genius that so many

Dr Burton's Description of the Antiquaries of

Rome, vol. i. pp. 28-33, 35. Burgess's Topography W. Gell's Topography of Rome and its Vicinity,

and Antiquaries of Rome, vol. i. pp. 342-345. Sir

vol. ii. pp. 407-413.

centuries since quitted the world without leaving even a name, will come with magical impression on his mind, while it is contemplatively darkening into the awe of antiquity. But he will be recalled. The sculptures, the inscriptions, the sanetuaries enclosed off for the special benefit, after death, of persons who had very dif ferent concerns during life from that of the care of their salvation, and various other insignia of the original character of the place, will help to recal him to the thought, that these proud piles were, in fact, raised to celebrate the conquest, and prolong the dominion, of the power of darkness over the souls of the people. They were as triumphal arches, erected in memorial of the extermination of that truth which was given to be the life of men.

As he looks round, and looks upward, on the prodigy of design, and skill, and perseverance, and tributary wealth, he may imagine to himself the multitudes that, during successive ages, frequented this fane, in the assured belief that the idle ceremonies and impious superstitions which they there performed or witnessed, were a service acceptable to Heaven, and to be repaid in blessings to the offerers. He may say to himself, Here, on this very floor, under that elevated and decorated vault, in a "dim religious light," like this, but with the darkness of the shadow of death in their souls, they prostrated themselves to their saints, or their " queen of heaven;" nay, to painted images, and toys of wood or wax, to some ounce or two of bread and wine, to fragments of old bones, and rags of cast-off vestments. Hither they came, when conscience, in looking either back or forward, dismayed them, to purchase remission with money or atoning penances, or to acquire the privilege of sinning in a certain manner, or for a certain time, with impunity; and they went out at yonder door in the perfect confidence that the priest had secured, in the one case, the suspension, in the other, the satisfaction of the Divine law. they solemnly believed, as they were taught, that, by donatives to the church, they delivered the souls of their departed sinful relatives from the state of punishment; and they went out at that door, resolved to bequeath some portion of their possessions, to operate in the same manner for themselves another day, in the highly probable case of need. Here they were convened to listen in reverence to some representative emissary of the

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