1

fancying." And he then adds, "I shall set down my apprehensions in the form of suppositions.' He concludes the same letter: "But by what has been said, you will easily discern whether in these conjectures there be any degree of probability, which is all I aim at. For my own part, I have so little fancy to things of this nature, that had not your encouragement moved me to it, I should never, I think, have thus far set pen to paper about them. What is amiss, therefore, I hope you will the more easily pardon."

The contrast which is thus afforded by the style of Newton to the manner in which Mr. Herapath and D. have written on the same subject, though exceedingly striking, will occasion no surprise to those who are accustomed to look for modesty and simplicity from minds in proportion as they are elevated and superior; and to expect that by how much experimental and philosophical truth is habitually contemplated with a clear and lucid perception, by just so much will these "conjectures," these feigned hypotheses," these "fancies," as Newton calls them, be esteemed doubtful and worthless.

66

There are many other parts of D.'s papers which it will be perceived I have not thought worth notice. When, for instance, he over and over again mockingly repeats without any sensible application or meaning, phrases which I formerly used; when too he asserts that I 66 am unacquainted with one of the commonest of Newton's ideas," speaks of my "conclusions too absurd to be entertained by any other person," "ridiculous conclusions," " temerity," "folly," " absurdity," " presumption," quibbling;" recommends me to avoid "equivocation," "subterfuge," "paltry attempt to evade," &c. with many other such insinuations and expressions, I have thought such things not deserving an answer; they only degraded the writer, if they were not indeed to be expected as the natural style and manner of one capable of the wilful misstatements and misrepresentations which I have exposed. Very many other similar misstatements and misrepresentations I have passed over without observation, where they were not interwoven with the propositions offered as answers to what I had previously written; I have shown enough to guard his readers against receiving as true, without examination, any of his assertions, however positively made; and the occupation of exposing them is too unpleasant and disgusting not to be avoided as much as it can be done with propriety.

With respect to the author of these papers, I certainly will not choose to attribute them to Mr. Herapath himself. I am aware that Mr. H. has been misled into a manner of attack upon what he calls the "illiberal opposition" from members of the Royal Society, and the "absurdities and strange paralogies" of Mr. Tredgold, which will give some countenance to the supposition that he might have been tempted to indulge in any longer paper, in the more liberal use of those terms not usual in philo

sophical controversies, but which are contained in the papers of D. Nor can it be unobserved that there is in these papers an apparent most intimate acquaintance with every part of the theory of Mr. H. both published and unpublished, and of the meaning, and even secret motives of the expressions and omissions in Mr. H.'s former papers, and at the same time an unusually energetic and triumphant interest in his philosophical opinions. These things may probably induce many persons to do Mr. H. the injustice to ascribe the papers to him, and, perhaps, therefore, he may think it worth while publicly to disown them; but for myself, having traced in them so many other unfounded assumptions, I can easily admit that these circumstances should be added to the number. The contrary too is not so easily conceived. Though indeed it is neither extraordinary nor unpardonable that a writer, having with no inconsiderable labour prepared a new theory in an important branch of natural philosophy, should be induced to value it rather more highly perhaps than its merits would warrant, and be led by a zeal and energy in its support, to use language not suited nor usual in philosophical discussions; it is not easily to be imagined that any one who feels within him any pulse of honourable ambition, to distinguish himself in the scientific discoveries and controver sies of the age, should almost at his very outset stoop to such a course of wilful misstatement and misrepresentation as D.'s papers exhibit, even to the extent of giving in inverted commas as the literal expressions of a writer, what was never written, meant, or thought by him. Such conduct must necessarily wither all his hopes in their very opening, by rendering it impossible for any person of honourable feeling to continue a correspondence with him.

I must indeed still think that Mr. Herapath has mistaken the path to philosophical science, in departing from experiment and observation, as the foundation of his opinions, and resting them on certain supposed properties of bodies, the knowledge of the existence of which is not deduced from the examination of phenomena, but springs from the imagination; contenting himself, if the theory be so framed, as to accord with some one considerable class of facts. Such was not Newton's mode of philosophical discovery. "Quicquid enim ex phænomenis non deducitur hypothesis vocanda est; et hypotheses, seu metaphysicæ, seu physicæ, seu qualitatum occultarum, seu mechanicæ, in philosophia experimentali locum non habent." (Newt. Opera, vol. iv. p. 493.) "The main business of natural philosophy is to argue from phænomena without feigning hypotheses," and when once the inductive philosophy is departed from, and the imagination, instead of fact and observation, is made the basis of theory, "there is no end of fancying." But however much it may be necessary that Mr. H. should change his course of philosophical thought and study before he can generally attain among scientific men

that rank as a philosopher to which he seems to aspire, his supporter D. has much more to change in his manner and style of writing, and his integrity as a controversialist, before he can deserve that any further arguments or observations of his should be regarded with any other feeling than contempt.

I remain, yours, &c.

C.

ARTICLE VIII.

Lunar and Solar Phenomena seen at Toula, in Russia.
By Mr. Longmire.

SIR,

(To the Editor of the Annals of Philosophy.)

Whitehaven, Aug. 8, 1822.

On Feb. 18, 1819, O. S. at about eight o'clock, p. m. the moon being nearly full, and nine degrees above the horizon, and the night still and very clear, with hard frost, there appeared near the moon six perpendicular spires of light; every two of

which had a common base in the middle, and in a horizontal line drawn through the moon's centre. The whole formed three perpendicular elongations of light; the middle one being on the moon, and the others, at 9° on each side of it. The point

a

B

a

b

D

of the upper spire at the moon was 16° above the horizon, and the inverted spire extended to the ground. The other elongations were half the length and breadth of the middle spires; whose base was equal to the apparent diameter of the moon; which, where these spires were seen, was enlarged one-fifth.

The colour of the elongation at the moon was a light yellow, unbroken for two thirds of the length; but nearer both points, it consisted of perpendicular blue streaks, somewhat lighter than the sky. Perpendicular blue streaks formed the other elongations. The stars shone through the streaks, and the sky was seen in the spaces between them

I have attached a sketch to this paper in which A is the moon, B the spires on it, C D the other spires; the parts a bare light yellow, and the parts c c, with the whole of the spires C D, are blue.

These very beautiful phenomena were visible to a spectator in the town, but not in the country adjoining it. The heat from

the houses seemed to melt a highly attenuated frosty vapour in the air, and in this heated medium, the spires were situated.

In the month of July, the same year, I observed a perpendicular elongation of faintly reddish light from the setting sun to the clouds. Its breadth was equal to the sun's diameter.

The western sky was covered with clouds, except an opening round the sun 15° high, and 12° wide. The departing rays, as is usual in this country in summer, coloured the edges of the clouds, wherever they penetrated, a scarlet red; and from the unevenness of the surface, gave the illuminated parts the appearance of flame.

This elongation of light appeared to extend forward nearly to the observer. The place where I stood was on rising ground near the town; at about half a mile in front was the river Oupa. In the vapour rising from the river, and the dampy holm on this side of it, originates this elongation of the sun's figure.

ARTICLE IX.

ANALYSES OF Books.

Memoirs of the Astronomical Society of London. Vol. I. London. 1822.

(Concluded from p. 153.)

The second of the three memoirs furnished by the Rev. William Pearson, is entitled, "On the Construction and Use of Micrometrical Eye-piece of a Telescope." The rationale of the new contrivance is given, previously to explaining the application of the doubly-refracting power to some of the most delicate measurements in practical astronomy; but this preliminary disquisition, which is extended to a considerable length, not admitting of intelligible abridgment, nor indeed bearing very materially upon the subject, we shall proceed to give Dr. Pearson's account of the application of this power. "In measuring the diameter of a small body of sensible dimensions, the sliding tube containing the prism must be steadily and gradually moved by the finger and thumb, backwards or forwards, until after adjustment for good vision, the two images of the object come exactly into contact, edge to edge: in this situation the distance indicated, will be the argument for entering the table of powers; and the power there seen by inspection, will be the proper argument for entering the table of measures, which will give at sight the apparent diameter, in seconds and parts of a second, without further correction. When the angular distance between two stars, satellites, or other luminous points, is required to be measured,

there will be two pairs of images formed, and these may fall in any direction with respect to each other; but turning the moveable tube with the prism round more or less will bring the four luminous images into one straight line; in which position, if the second and third images coincide exactly, the measure will at once be correct; but if not, the distance between the lenses must be varied until this coincidence takes place. Should the prism used be found to have too great or too small an angle at any of the distances marked in the scale, it must be changed for another having a more suitable angle, and must be adjusted as before directed. In all cases where one of two contiguous stars is much smaller in appearance than the other, and is yet visible through the prism, the small one will be lost by super-position on the larger, and must, therefore, be made to pass over its centre by a slow motion given by rotation of the tube, when an estimate may be made of the exactness of the central transit; or otherwise, the four visible images may be formed into an exact square, when it will appear whether or not the bounding sides of the figure are equal to each other; and if they are, the proper distance will be indicated in that position." These directions are illustrated by a tabular account of the actual application of the micrometrical eye-piece to various celestial measurements; and the memoir concludes with extensive tables of powers and measures, of which it is not possible to give an intelligible abridgement.

Of the sixth memoir, " On the Construction of a New Position-Micrometer, depending on the Doubly-refractive Power of Rock Crystal," a very short notice will be sufficient. Before proceeding to describe the addition made to the former instrument, a method is mentioned by which Dr. Pearson varies the constant angle of a prismatic solid, by the juxta-position of a second solid of double refraction; a method which, says he, “to me is new, but which probably may be known to those philosophers, who have studied more minutely the laws of the polarization of light." By what arrangement the eye-piece micrometer with double images is converted into a positionmicrometer, the following extract will render sufficiently obvious. "When a crystal of the micrometer was applied before the eyepiece of a transit instrument, all the spider's lines, as was expected, were seen double; as was also a star or other luminous point placed at a distance. But turning the prism round a little, soon brought all the images of the vertical lines into contact with the lines themselves, and the coincidence was perfect as to breadth, but not as to length of the lines in question: the image of the star in the mean time revolved round the star itself without coming into contact. Likewise when two stars, in the same field of view, are examined through a doubly refracting prism, a line connecting either star and its own image will be truly vertical, when the image of the vertical line is coincident with the