stone stands conspicuous. The Eddystone rocks are almost in the line, but somewhat within it, which joins the Start and the Lizard points; and as they lie nearly in the direction of vessels coasting up and down Channel, they were formerly very dangerous, and often fatal to ships, until the erection of this light-house.

“Their situation, with regard to the Bay of Biscay and Atlantic Ocean, is such that they lie open to the swells of the bay and ocean from all the south-western points of the 'compass; which swells are generally allowed by mariners to be very great and heavy in those seas, particularly in the bay of Biscay. The soundings from the south-westward to these rocks are from eighty to forty fathoms, and until you come very near the rock they are no where less than thirty, so that all the heavy seas from the south-west rush uncontrouled upon them with the utmost fury. The force and height of these seas is increased by the circumstance of the rocks stretching across the Channel in a north and south direction, to the length of some hundred fathoms, and also by their lying in a sloping manner to the south-west quarter. The effect of this slope on the rush of waters in stormy weather is terrific; and after a heavy gale, where all appears superficially calm, the ground swell in the neighbourhood of these rocks is so prodigious, as to cause so rough a sea that no boat can land upon them. These difficulties appeared almost insuperable, but the daring genius of man has surmounted them all. Another circumstance, which considerably damped all hopes of working upon these rocks, was a sudden drop of their surface, forming a step between four and five feet high so that the seas, which even in moderate weather beat with a heavy swell against this part, meeting with so sudden a check, the sprays are frequently impelled thirty or forty feet upwards. The Eddystone rocks, therefore, remained for ages an object of the mariner's fears, but at length, in the year 1696, a gentleman of Littlebury, in Essex, whose name was Henry Winstanley, undertook to erect a lighthouse on this fearful spot. In the course of four years the edifice was completed, and the architect felt so assured of its stability, that he wished he might be within it "during the greatest storm that ever blew under heaven." His wish was unfortunately gratified: on the 26th of November, 1703, the most tremendous storm that is detailed in the records, not only of this, but of any other country, swept away, in a few short

hours, the perishable and boasted work of man, and left only the bare rock, standing proudly erect. Mr. Winstanley and all his people were buried in the tempestuous deep, and no trace of the unwearied and dangerous labour of four years remained, except a few large irons which fastened the building to the rock!"

EDWARD." Poor creatures! What a fate! I am surprized that any body, after such an accident, would venture to erect a second."

DR.WALKER." Patience and perseverance conquer most things. In the year 1709, Mr. John Rudyerd, a silk mercer, undertook the dangerous task; and although the light-house was erected only of wood, it yet resisted the fury of the winds and waves during forty-six years, and was at last destrcyed by fire.

"Mr. Smeaton, the celebrated engineer, was then chosen as a person well calculated to repair so important and national a loss. On the 2nd of April, 1757, he laid the foundation of the present structure. The rock which slopes towards the south-west, is cut into horizontal steps, into which are dove-tailed and united by a strong cement Portland stone and granite. The whole to the height of thirty feet, from the foundation is a solid mass of stones, engrafted into each other, and united by every means of additional strength. The building has four rooms, one over the other, and at the top a gallery and lantern. The stone floors are flat above, but concave beneath, and are kept from pressing against the sides of the building by a chain let into the walls. It is nearly eighty feet high, and since its completion has been repeatedly assailed by the fury of the elements without suffering the least injury."

EDWARD." What a life the poor men must have who at tend to the light. In what manner are these light-houses illumined?"

DR. WALKER." By means of lamps and reflectors. Formerly they were lighted by immense coal fires; but the present plan has many and great advantages. The light, in the first place, is much more brilliant, is less expensive, and is not so liable to be affected by the weather, while the man who has the charge of it is neither exposed to wet or cold. And now, Edward, ring the bell: it grows late, and we must rise early in the morning."

SECTION V.

OF AERIAL PHENOMENA.

OUR travellers began their journey with the sun on the following day; and, after a pleasant ride, they arrived towards evening at Upton, and from thence proceeded to Great Malvern. The picturesque beauty of the surrounding scenery, glowing with an evening sunset, was considerably heightened by the gradual appearance of the resplendent arch of heaven; while the sweet south, upon a bank of violets, refreshed and perfumed by a vernal shower, came wafting to them, and regaled their senses with all the sweets of spring. "How resplendent are those colours!" said Edward, as the rainbow became every instant more distinct and brilliant.

"Yes," replied the Doctor," and of all the instances of refrangibility of light, or, in other words, the separation of its primary colours, none is more remarkable, than that of the Iris, or rainbow. It is formed, in general, by the reflection of the rays of the sun's light from the drops of falling rain, though frequently it appears among the waves of the sea, whose heads, or tops, are blown by the wind into spray and small drops, and it is sometimes seen ground, when the sun shines on a very thick dew.

on the

"The immediate cause of this refractibility is this. When rays of light pass through one medium and enter another of different density, they are diverted from their former course, and are then said to be refracted. Hence a ray of light entering a globule of rain, instead of passing through the centre of the globule, and out at the opposite point by which it entered, it will be driven towards another marginal position, and form an angular line coequal to the obliquity, with which it deviates from a right line on its entering the globule, just as a stake or oar, plunged obliquely into a river, appears to be broken at the point at which it enters the waNow this ray of light does not, of course, illumine the whole globule, and the unillumined part of the rain dropforming a dark back ground to the ray of light, the globule

ter.

has the property of a mirror. The ray which is thus formed is again reflected by the mirror thus produced, and it assumes a triangular figure. This angle of light has the property of a prism, and exhibits what are called prismatic colours. The spread of this angle must depend upon the dia. meter of the globule which produces it, and its point being obtuded or softened to the eye by the distance through which it is beheld, the angle must be converted into an arch, thus, and hence a beautiful and variegated bow is produced. The drops of rain falling continually, a

new rainbow is produced every moment: and as each spectator has his particular situation from which he observes this phenomenon, it so happens that no two persons, properly speaking, can see the same rainbow.

"The beautiful colours of the rainbow, to Pliny and Plutarch, appeared an object we might admire, but could never explain; and the priests of antiquity always preferred the wood, on which the rainbow had appeared to rest, for their sacrifices, religiously supposing this wood had a perfume peculiarly agreeable to the gods.

"Cascades and fountains, whose waters are in their fall divided into drops, exhibit rainbows to a spectator, if properly situated during the time of the sun's shining; and wa. ter blown violently from the mouth of an observer, whose back is turned to the sun, never fails to produce the same phenomenon.

"This appearance is also seen by moon-light, though seldom vivid enough to render the colours distinguishable; and the artificial rainbow may be produced even by candle-light, on the water which is ejected by a small fountain, or jetd'eau. All these are of the same nature, and dependent on the same causes, viz. the various refrangibility of the rays of light.

"The colours observable on soap bubbles, and the halos which sometimes surround the moon, are also referable to the same origin.

"We shall prove this if we darken a room, and permit the sun to shine into it through a small hole in the windowshutter, so that the rays of light be made to fall upon a glass prism: then will these rays, in passing through this prism, suffer different degrees of refraction, and by that means be parted into different rays, which being received upon a sheet

of white paper, will exhibit the following colours, viz. red, orange, yellow, green, blue, indigo, and violet; and if the whole spectrum, or image, be divided into 360 equal parts, the red will occupy 45 of these parts, the orange 27, the yellow 48, the green 60, the blue 60, the indigo 40, and the violet 80.

"As a ray of the sun may be separated into these seven primitive colours, so, by their mixture in due proportions, may white be produced. White, therefore, is the mixture of all the colours, as black is the want, or deprivation, of colour: and this may be proved, by fixing pieces of cloth of all the seven different colours, on the rim of a wheel, and whirling it round with great velocity; when it will appear to be white. Though seven different colours are distinguishable in the prismatic spectrum, yet, upon examining the matter with more accuracy, we shall see that there are, in fact, only three original colours, red, blue, and yellow; for the orange being situated between the red and yellow, is only the mixture of these two: the green in like manner, ariscs from blending the blue,and yellow, and the violet results from the blue and red."

Before our travellers reached the principal inn at Malvern, it was nearly dark, and by the tine dinner was over, evening was too far set in to allow them to walk; they therefore drew their chairs to the fire-side, and Dr. Walker renewed the conversation upon some of the various phenomena of the air.

"You have heard, I dare say, of the Fata Morgana, Edward," enquired the Doctor. "But you never, perhaps, thought of enquiring into its causes. In Scotland these grotesque and sometimes beautiful illusions, are called Glamer; the English sailors call them Fog-banks, and the French Mirage. In order to illustrate this delusion as clearly as may be, it is necessary first of all to call your attention to the variable state of the atmosphere; which is commonly of an homogeneous, or equable tenuity, and consequently suffers the sun's rays to penetrate it without any obstruction or change; but it is occasionally irregular, and composed of parts or bodies of a denser medium than its general texture and constitution, in which case the fluent ray, if it do not enter the denser medium in a direct or perpendicular line, will be either reflected, or refracted, or both; and the object surveyed through it assumes a new, and not unfrequently