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To the Editor of the Monthly Correspondent.

Dec. 24th, 1813.

I PRESUME from the nature of your proposed work, that all experiments and observations on Light and Colours will find a place in your useful publication; the former from its relation to the noble science of Astronomy, the latter for their utility in the arts and domestic occurrences of life. With the experiments of Newton and Herschel on this subject the public are well acquainted; and latterly Dr. Brewster has made some valuable additions to our imperfect knowledge of this most intereresting matter. The labours of the latter gentleman have been detailed to the Royal Society during three successive Thursdays, and only terminated last night. Dr. Brewster, availing himself of Biot's discovery of the polarization of the rays of light, has pursued his experiments with thin plates of agate, by which, and Iceland spar, he repeatedly poralized and deporalized light; he also discovered the poralizing, deporalizing, and what he calls the neutral axis of the agate, and the extraordinary effects respectively produced in the colours exhibited, particularly on the coloured rings, wavy pencils, and rainbow-like appearances.

I have made several experiments on the coloured concentric rings, noticed by Newton, and latterly examined, with little success, by Herschel; I have also repeated some of Dr. Brewster's experiments, with results somewhat different from them all. At present, other avocations prevent me from laying before you a detailed account of those appearances; but one fact I shall here state, which may perhaps contribute to aid the researches of those who may wish to repeat such pleasing experiments. It is this-That in all experiments made either with lenses, pieces of ground or plate glass, or agate, the colours of the rings and the pencils of rays always depended, or were modulated by the thickness of the ma

though astronomers here, and on the Continent, were watching its approach with great anxiety.

From the beginning of our era to this time, it is probable, according to the best accounts, that there have appeared 500 Comets. Before that time, above 100 others are mentioned in history; but, perhaps, half of these, had they been accurately observed, would not have proved Comets. When, however, we consider that many others may not have appeared, from being too near the Sun; from appearing in moonlight; from being in the other hemisphere; from being too small to be perceived; or which may not have been recorded; it is reasonable to suppose that the whole number is much greater. It is, on the other hand, very likely, that of the Comets that have been recorded as seen, the same may have appeared several times, and therefore the number may be less than is stated.

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Remarkable Comets appeared in the years 1807, 1808 and 1811; of these we may, in a subsequent Number, give enlarged accounts. We shall only observe, 1. That of the ninety-eight Comets, whose elements have been observed and calculated previously to the year 1808, twenty-four have passed between the Sun and orbit of Mercury; thirty-two between the orbits of Mercury and Venus; twenty-one be tween the orbits of Venus and the earth; sixteen between the orbits of the Earth and Mars; three between the orbits of Mars and Ceres; and one between those of Ceres and Jupiter.-2. That thirty-two Comets have appeared between the months of April and September, and sixty-six between September and April.-3. That the greatest part of the Comets have their perihelion nearest to their ascending nodes.—4, That fifty Comets move from west to east.-5. That the orbits of the Comets are not confined to any particular region of the heavens, like the planets that have long been known, but seem to be inclined to every possible angle of the ecliptic.

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To the Editor of the Monthly Correspondent.

Dec. 24th, 1813.

I PRESUME from the nature of your proposed work, that all experiments and observations on Light and Colours will find a place in your useful publication; the former from its relation to the noble science of Astronomy, the latter for their utility in the arts and domestic occurrences of life. With the experiments of Newton and Herschel on this subject the public are well acquainted; and latterly Dr. Brewster has made some valuable additions to our imperfect knowledge of this most intereresting matter. The labours of the latter gentleman have been detailed to the Royal Society during three successive Thursdays, and only terminated last night. Dr. Brewster, availing himself of Biot's discovery of the polarization of the rays of light, has pursued his experiments with thin plates of agate, by which, and Iceland spar, he repeatedly poralized and deporalized light; he also discovered the poralizing, deporalizing, and what he calls the neutral axis of the agate, and the extraordinary effects respectively produced in the colours exhibited, particularly on the coloured rings, wavy pencils, and rainbow-like appearances.

I have made several experiments on the coloured concentric rings, noticed by Newton, and latterly examined, with little success, by Herschel; I have also repeated some of Dr. Brewster's experiments, with results somewhat different from them all. At present, other avocations prevent me from laying before you a detailed account of those appearances; but one fact I shall here state, which may perhaps contribute to aid the researches of those who may wish to repeat such pleasing experiments. It is this-That in all experiments made either with lenses, pieces of ground or plate glass, or agate, the colours of the rings and the pencils of rays always depended, or were modulated by the thickness of the ma

terial refracting the light. This fact has not yet been noticed by any philosopher with whom I am acquainted; and it will, I doubt not, when more extensively examined, prove of some advantage to opticians, not merely in making microscopes, but also telescopes, and all kinds of optical instruments. It appears, that we are yet very inadequately acquainted with the effects of diaphanous bodies in refracting light; and that although the prism has long been a subject of admiration to the multitude, the analysis of light, so admirably commenced by Newton, has not improved a tittle during the whole of the last century. Should you think these remarks worthy a place in your work, you will oblige a friend to every useful and scientific undertaking. Yours, &c.

P. P. P.

To the Editor of the Monthly Correspondent,

SIR,

A PROSPECTUS of your work having fallen into my hands, I am happy to express my approbation of the manner in which you have stepped forward with a publication that seems calculated to dispense at once information to the student, and to open a channel for the professors of this sublime art, to display the power of the stars over every principal action of human existence.

Should you insert this nativity, you will have my future correspondence,

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This Nativity is a most striking and indubitable proof of sidereal influx, and the baneful effects which will always be found to arise from similar positions. Here the Sun is lord of life, angular, and severely afflicted by the malefic square of Saturn in the world, who is cardinally and angu larly posited in a situation so as to restrict existence to a moment. Jupiter, who rules the Sun's place, is bodily with the lesser infortune, while the latter also disposes of the Moon. Under such an evil combination of planetary rays, with neither of the benefics to assist, as is the case here, it is impossible but that death should occur within the period of nutrition.

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