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pearances with which we become acquainted by its means.

The glasses employed for optical_purposes are denominated lenses, and are formed by the process of grinding into the following figures,

oblique annual course he would soon learn |
to identify the variety and succession of the
seasons. As population increased, the cul-
tivators of the soil sought and obtained
some knowledge of the celestial motions,
that they might with certainty determine
both the "seed time and the harvest." In
pastoral life also, such knowledge would be
found essential to regulate the migrations Axis
of the shepherd; and history informs us
that the Chaldeans, enjoying the leisure of
such a life, with the facilities of the spa-
cious and unclouded horizon of their native
plains, were among the foremost in observ-
ing and recording the more striking of the
celestial phenomena.

It has been said, that "an undevout astronomer is mad." And if our remote ancestors of the earliest ages could find, "in looking through nature up to nature's God," their hearts warmed, and their devotional feelings increased with every new accession to their knowledge, which must necessarily have been acquired with unassisted vision, what must have been the feelings of astonished and pious excitement, in him who first directed that wondrous instrument, the telescope, to the starry heavens! It imparts a range of ken more than possessed by eagles' eyes, and exhibits to our finite powers a magnificent view of the immensity, the beauty, and the harmony of that universe, of which the world we inhabit forms so insignificant a member. And experience teaches us, that the boundary of our vision thus extended, lies nowhere but in the imperfection of our telescopes; for who can say how far the universe extends, or where are the limits of it?-where the Creator stayed "his rapid wheels," or where he "fixed his golden compasses?" That man is little to be envied (be his acquirements or possessions what they may) who can with a cold indifference view these wondrous scenes; more especially if, understanding the nature and constancy of the celestial motions, he cannot both feel and acknowledge that "the heavens declare the glory of God, and the firmament showeth his handywork."

It is our present object to bring before our readers a familiar account of the principles of that instrument by which our faculty of vision is so much assisted; and after explaining the shape and arrangement of those glasses which constitute the telescope, and in that form produce such remarkable effects, we purpose introducing, by way of illustration, a short descriptive account of those celestial bodies and ap

1 2 3 4 5 6 7 8

of the lens.

Figure 1. Represents a prism as viewed end-wise, and is in shape like an equilateral triangle.

2. A plane glass, which is perfectly flat on both sides, and of equal thickness in all its parts.

3. A spherical lens, or perfect globe, all the points on its surface being equally dis tant from its centre.

4. A double convex lens, which is a solid piece of glass, having two convex spherical surfaces, each in shape like the outside of a watch-glass.

5. A plano convex lens, which is flat on one side and convex on the other.

6. A double concave lens, which is concave (or hollowed out like the inside of a watch-glass) on both sides, and may be equally or unequally concave.

7. A plano concave lens, which is flat on one side and concave on the other.

8. A meniscus, which is a lens, one of whose surfaces is convex, and the other concave. As the convexity exceeds the concavity, it may be regarded as a convex lens.

9. A concavo-convex lens, which also has one of its surfaces convex and the other concave, but as the concavity exceeds the convexity, it may be regarded as a concave lens.

An imaginary line passing through the centres of the curved surfaces, and perpendicular to the plane surfaces of lenses, is called their axis: thus, in the figure below, let A B represent a double convex glass, the surfaces being segments of the two equal circles, then a line passing through the two centres c c of the circles would be called the axis of the lens; the same holds good of all the other lenses, as shown in our former figure.

The peculiar properties of such of these

lenses as are more immediately connected with our subject, in the refraction of the rays of light, (that is, bending the rays, or causing them to change their course,) we shall now explain.

It must be premised that rays of light proceed in straight lines, but are diverted from their course, or refracted, as it is termed, when they pass from one medium to another, as shown by the following familiar instance:-A straight stick when partly immersed in water, appears to be bent upwards, at the surface of the fluid; which is an optical deception, and arises from the rays of light being bent or changed in the direction of their course, as soon as they reach the surface of the water, in passing out of it. The density of the water being so much greater than that of the air, is the cause of this great refraction, and produces the apparent distortion of the stick.

Let us now consider the refraction of rays by a convex lens, which suppose to be A B in the figure below, whose axis is in the direction of the straight line c », and let

would distinctly see a perfect image of the object c formed on the ground glass, and by steadily keeping the eye in the same position, the ground glass may be removed, and the image will appear in the same spot suspended in the air. What an astonishing effect is thus produced by a convex lens! the object supposed to be very remote at c, is suddenly transported as it were to h, from which the eye must undoubtedly receive a very different impression from what it would do if, withdrawing the lens, it were to view the object c immediately.

The focus h, where the image of the distant object is formed, has a remarkable property; and we shall digress in this place to speak of it. Suppose the sun to be the object at c, the rays which fall on the lens are all collected at h, and being endowed with the quality of heating, it is natural that the concourse of so many rays at one point should produce a degree of heat, capable of setting on fire any combustible matter that might be placed there; hence a convex lens is commonly denominated a burning glass. The image formed at the focus h will be an inverted image of the object c, as will readily be understood from the

following figure. -D

a

there be an object at c, which imagine to be at a great distance from the lens. This object diffusing rays of light in all directions, some of them will pass through the lens A B, as ce, cf, and cg, of which ce in the direction of the axis of the lens will suffer no refraction, but continue the same rectilineal course towards D. The other two rays cf and c g (as well as all intermediate rays) in passing through the lens nearer the edge, will be so refracted both at entering and departing, that they will afterward meet the axis, as at h the focus of the glass, where they will (if not intercepted) cross each other's path, and continue in the same straight lines Bi and A k. The rays of light cf and cg would, if no lens had interfered, have continued onward in the direction they first had; but undergoing refraction at A B, they are compelled to change their directions, and proceed as if they had emanated from the point h, where an image of the object c would be formed. If a piece of ground glass, transparent paper, or a plate of glass having one surface covered with a dried film of skimmed milk, be held up at h, a person looking at it from D a few inches behind the glass,

A

B

Suppose the man at ▲ was observed through a lens at B, the rays which fall upon the lens will, as before stated, be refracted, and form an image on the other side. We before had occasion to remark, that those rays which pass through the centre of the lens in the direction of its axis, suffer no refraction; the same is true of all rays which pass through the centre, whether they fall upon the surface in the direction of the axis or otherwise, because the opposite surfaces in the direction of such rays are parallel to each other. Therefore the image of the man's head must be formed in the line a b, which is the direction of the ray passing from the crown of his head through the centre of the glass, and that of his feet in the line c d, forming an inverted image of the man.

The image db may now be considered a new object, and by placing another lens at c, an additional image of this image would be formed at ef, exactly in the same manner as if d b was a real object. But since the new image must be inverted with

respect to d b, it will be an erect image of the object or man at A; so that by using one or more lenses, direct or inverted images may be obtained at pleasure.

The reader may now form an idea of the method by which opticians cause the telescopes intended to view terrestial objects, to show them erect or in their natural position. But those constructed for astronomical purposes show them inverted; to the astronomer this apparent inversion being of no consequence, and as fewer glasses are placed in his telescopes, the objects appear brighter, (which is of greater importance to him,) the rays having less dense medium to pass through; for in every refraction some rays must necessarily be lost. And as the brightness of the object depends upon the quantity of rays which reach the eye, it is evident that the larger the lens, the more rays it will receive and transmit; consequently a telescope of large aperture must be the most desirable, especially for astronomical purposes.

SCRIPTURE EXPLANATIONS.-No. XXXII. "He speaketh with his feet, he teacheth with his fingers."-Prov. vi. 13.

It should be remembered, that when people are in their houses, they do not wear sandals; consequently their feet and toes are exposed. When guests wish to speak with each other, so as not to be observed by the host, they convey their meaning by the feet and toes. Does a person wish to leave a room in company with another, he lifts up one of his feet; and should the other refuse, he also lifts up a foot, and then suddenly puts it down on the ground.

"He teacheth with his fingers." When merchants wish to make a bargain in the presence of others, without making known their terms, they sit on the ground, have a piece of cloth thrown over the lap, and then put each a hand under, and thus speak with the fingers! When the brahmins convey religious mysteries to their disciples, they teach with their fingers, having the hands concealed in the folds of their robes.-Roberts.

BOTANY.-No. XXI.

GERANIACEE.

WE are just going to take a passing view of a family of plants not less familiar to us than they are deserving of a more intimate acquaintance than it is commonly their lot to obtain among us.

One of the most frequent ornaments of a cottager's window is a geranium, and of those flowers which variegate the borders of our domestic enclosures, some of the brilliant specimens of this sort form not the least considerable portion. Among the ordinary points of resemblance by which the members of this family are bound together, as by the common ties of affinity, we may notice, in the first place, the constant presence of ten stamens, with half that number of petals, that is, of coloured parts which are unconnected with each other. These stamens are united at their base by the mutual junction of the flat tened filaments. The style or central pillar is usually prominent, and is ultimately prolonged into a beaked point, like the bill of a bird, or specially that of a crane, whence the plants have long since obtained the name of geranium, or cranesbill. The style terminates in five stigmata or rosy points, which descend down along the outside of this central pillar, and, at the base, are each of them enlarged into a seed-vessel, containing one seed. Hence, at the base, we find a circle consisting of five distinct protuberances; these finally separate, and are lifted up out of their original situation by the descending threads, which we have just described, as respectively a continuation of the stigmata, or rosy points. This operation of lifting up the seeds with their cases, is performed by the twisting of the threads, either in a spiral direction, like a screw, or by simply curling up like a lady's ringlets. The effect of these curious processes, is to place the seed in a favourable position for being wafted to a distance, by that general medium of distribution, the wind. If we look with an eye that covets instruction, at the flower-stem just below the calyx, we shall perceive, in some instances, a spur, and in all others, an enlargement on the upper side, which is hollow, and is extended various lengths down the flower-stem, so as to afford an auxiliary mark for specific distinction.

This whole family were once comprehended under one genus, geranium; but of late, it has been found more convenient for the purposes of study, to distribute the species known at present, into five genera, three of which may be distinguished, and exemplified in the following

manner.

Geranium. All the stamens bearing anthers when the bud first opens, with a little gland at the base of each of the

longer stamens. Seeds lifted by the coiling up of their supporters, which, in this position, resemble a spring. This genus will be exemplified by looking at the jagged cranesbill, (geranium dissectum,) very common by the road-sides, or by reference to the herb robert, (G. robertianum,) which is very often seen on ditch-banks under hedges. Its general resemblance to the geraniums in our pots, its pink red flowers, and beaked fruit, added to the strong disagreeable smell of its foliage, will not fail to denote it to the curious eye, while a close examination of its peculiarities will afford an agreeable lesson of botanical instruction. Erodium. In this genus we miss the spur or tube in the flower-stalk. Of the ten stamens, five bear anthers, and five are barren, at the base of which latter five, we meet with five glands corresponding to them in number. But what is most likely to engage our attention is, the screw or worm-like twisting of the supporters, to raise the seed from its lodging below.

An example may be sought for in the hemlock cranesbill, (erodium cicutarium.) This plant may be distinguished by its divided wing-like leaf, its red flowers, which have the general likeness of the geraniums, and its strong smell: it is very common by road-sides. There will be no difficulty, either in finding or in recognising the hemlock-leaved cranesbill, since the similitude of the individuals is so striking, that to know one, is to know all, as far as recognition is concerned.

Pelargonium. Upper division of the calyx, running into a tube, which appears upon the flower-stalk, descending in a direction between the upper pair of petals, which form a pair differing in shape from the rest. The fertile stamens vary from four leaves to seven, while the supporters are beaded on the inner side, and twist spirally, to raise the seed from its lodging. Examples are to be found among all the garden varieties, which are originally natives of the Cape of Good Hope, but by the cultivator's skill they have been improved and multiplied by crossing, so that, oftentimes, in our greenhouses and conservatories, few plants make a more beautiful and conspicuous figure.

One of the oldest, and not the least attractive and beautiful, is the horseshoe geranium and its varieties, which bear the figure of that part of a horse's

equipment upon the leaf. But as varieties are every day increasing, it would not suit our limits to give an enumeration. Some shown us the other day, of peculiar splendour, bore the names of individuals now living, distinguished both in military and civil stations.

THE HUMAN COMPLEXION.

BISHOP HEBER observes, "I thought it remarkable, that though most of the male Indian deities are of a deep brown colour, like the natives of the country, the females are no less red and white than our porcelain beauties, as exhibited in England. But it is evident, from the expressions of most of the Indians themselves, from the style of their amatory poetry, and other circumstances, that they consider fairness as a part of beauty, and a proof of noble blood. They do not like to be called black, and though the Abyssinians, who are sometimes met with in the country, are very little darker than they are themselves, yet their jest-books are full of taunts on their charcoal complexion. Much of this has probably arisen from their having been so long subjected to the Moguls, and other conquerors, originally from northern climates. India, too, has been always, and long before the Europeans came hither, a favourite theatre for adventurers from Persia, Greece, Tartary, and Arabia, all white men, and all in their turn possessing themselves of wealth and power. These circumstances must have greatly contributed to make a fair complexion fashionable. It is remarkable, however, to observe how surely all these classes of men, in a few generations, even without any intermarrying with the Hindoos, assume the deep olive tint, little less dark than a negro, which seems natural to the climate. The Portuguese natives form unions among themselves alone, or, if they can, with other Europeans, and yet have they, during a 300 years' residence, become as black as Caffres. Surely this goes far to disprove the assertion, that climate alone is insufficient to account for the difference between the European and the negro. It is true, that in the negro are other peculiarities to which the European colonists show no approximation, and which undoubtedly do not appear to follow so naturally from the climate, as that swarthiness of complexion which is the sole distinction between the Hindoo and the European. But if heat produces one change, other peculiarities of climate may produce other

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in India where, only a few years ago, the most revolting barbarities were practised, "I was mentioning to bishop Heber, how forcibly it had struck me, during the service, in that hall, where, a few years ago, the most savage tyrant received his miserable subjects, a christian prelate was

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and additional changes; and when such peculiarities have 3000 or 4000 years to operate in, it is not easy to fix any limits to their power. I am inclined, after all, to suspect that our European vanity leads us astray in supposing that our own is the primitive complexion, which I should rather suppose was that of the Indian, half-now administering the solemn ordinances way between the two extremes, and per- of our religion. He leaned his head on haps the most agreeable to the eye and the his hand, and burst into tears. How instinct of the majority of the human race. wonderful,' said he, is the providence A colder climate, and a constant use of of God, in the economy of his church! clothes, may have blanched the skin as Never was any people entrusted with effectually as a burning sun or nakedness such a power of doing good as England may have tanned it. Thus, while hardship, now is! What a fearful responsibility additional exposure, a greater degree of rests on the government and its minisheat, and other circumstances with which ters; on the nation and all its children; we are unacquainted, may have deteriorated and, above all, on our church and its the Hindoo into a negro, opposite courses | rulers ! Such were the remarks made may have changed him into the progres in the palace of the deposed Emperor of sively lighter tints of the Chinese, the Per- Candy on this memorable morning." sian, and the European."

EXPENSES AT ETON IN THE
SIXTEENTH CENTURY.

OF the expenses incurred for schoolboys at Eton, early in the reign of Elizabeth, we find some curious particulars in a manuscript of the time. The boys were sons of Sir William Cavendish, of Chatsworth, and the entries are worth notice, as show ing the manners of those days. Among the items, a breast of roast mutton is charged ten-pence; a small chicken, four-pence; a week's board, five shillings each, besides the wood burned in their chamber; to an

old woman for sweeping and cleaning the chamber, two-pence; mending a shoe, one penny; three candles, nine-pence ; a book, Esop's Fables, four-pence; two pair of shoes, sixteen-pence; two bunches of wax lights, one penny; the sum total of the payments, including board, paid to the bursers of Eton College, living expenses for the two boys and their man, clothes, books, washing, &c., amount to twelve pounds, twelve shillings, and seven-pence. expense of a scholar at the university in 1514 was but five pounds annually, affording as much accommodation as would now cost sixty pounds, though the accommodation would be far short of that now customary at Eton.-Domestic Life in Eng

land.

The

ENGLAND'S RESPONSIBILITY. MR. ROBINSON remarks, adverting to the fact of a confirmation being held in a place

FORGETFULNESS.-A wretch that is condemned to die to-morrow cannot forget it, and yet poor sinners, that continually are speedily to see the majesty of the Lord, uncertain to live an hour, and certain to their inconceivable joy or terror, as sure as they now live upon earth, can forget these things for which they have their memory, and which one would think should port of a cannon doth a whisper, or as the drown the matters of this world, as the resun obscures a poor glow-worm. Oh wonderful stupidity of an unregenerate soul! oh wonderful folly and distractedness of the ungodly, that ever men can forget-I say nal woe, and the eternal God, and the again, that they can forget eternal joy, eterplace of their eternal and unchangeable and there is but the thin veil of flesh be-abode! when they stand even at the door, tween them and that amazing sight, that eternal gulf, and they are daily dying and stepping in!-Baxter.

THE BELIEVER. - A believer's heel may be bruised, but his vital parts are out of reach, Zech. ii. 8, 1 John v. 18.Cole.

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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