Chapter XX: Letter XIX: gives a definition of the ellipsis, which would be a (14)

Set the cone as accurately as you can to the day and hour, then turn the declination segment round, and elevate the index till you can see the star through the sights P, O. Note the declination at the segment K, cut by the index M, and against the corresponding degree of the scale you will find the star on the projection.

If no such star can be found, you may then conclude that it is a planet, or a new star.

By this means the place of the moon, of a planet, or a comet, may be noted down, from time to time, and their apparent paths traced out. [p377]

PROBLEM 5. To find the hour of the day by the sun.

Turn the segment K, and elevate the index M, till the sun is seen or shines through the sights O, P, and the scale L point to the hour and minute on the circle E F G.

PROBLEM 6. To find the hour of the night by means of a star.

Direct the index M to the star, so as to be seen through the sights P, O; then laying hold of the scale L, to keep it in that position, turn the cone till the star on the projection is cut by the scale, when the day of the month on the circle at the bottom of the cone will coincide with the hour and minute on the circle E F G.

This instrument, though not capable of extreme accuracy, might, by means of careful workmanship, and the addition of a small telescope, be made sufficiently so for finding stars in the day time; but such a one as that now described will answer all the purposes of a learner, and enable very young people to acquire a correct and extensive knowledge of the stars in a very short time.

The surface of a cone has been adopted for the projection, in preference to that of a globe or planisphere, having been found, after repeated trials, the figure best suited to the nature of the instrument.

_An Introduction to the Comparative Anatomy of Animals, compiled with constant reference to Physiology, and elucidated by twenty copper-plates_. By C. J. Carus, M.D., &c. Translated from the German, by R. T. Gore, Member of the Royal College of Surgeons in London.

If we except Sir Everard Home’s splendid work on comparative anatomy, we have no original treatise on that subject which deserves notice; and even Sir Everard’s lectures must rather be considered as a series of essays on detached parts of that branch of science, than as a regular and systematic view of it. We have long been acquainted with the work of Dr. Carus, and have always considered it as a laborious and accurate epitome of the principal facts and authorities in the study to which it relates. From the immense field of inquiry which it embraces, it is necessarily complicated, and [p378] in some places a little obscure, but it is entirely free from those speculative and hypothetical wanderings which are too characteristic of the German school of physiology; and though it contains some systematic notions in which we cannot acquiesce, and a few new words, not the most harmonious in the world, it may very safely and properly be recommended to the student as a text-book, and to the proficient as a work of reference. The plates by which it is illustrated are upon an economical scale, sometimes rather too small to be distinct, but they are otherwise accurate and carefully drawn; and we are aware that it is impossible to obviate these objections without incurring such expense as would probably render the work inaccessible to those readers for whom it is principally compiled.

Mr. Gore has assiduously and faithfully executed the difficult task of translation, and has added no inconsiderable quantity of new and important matter in the form of notes, rendering the English work more complete, and upon many points much more satisfactory than the original.

_Experiments to determine the Comparative Value of the principal varieties of Fuel used in the United States, and also in Europe, and on the ordinary Apparatus used for their Combustion_. By Marcus Bull. Philadelphia and London, 1827.

The population of London and its immediate environs may be estimated at about two millions, and the annual consumption of coals within the same district does not fall far short of two millions of chaldrons, or seventy-two millions of bushels. Of this prodigious quantity of inflammable matter, a very considerable portion escapes combustion, and lodges in the form of soot in our chimneys, or is vomited forth to contaminate and cloud the atmosphere of the metropolis: so great is this loss, that independent of the mere advantage of getting rid of smoke, its prevention is an important economical problem; and though the rage for smoke-burning has passed over, we are quite certain that the subject still deserves the most serious attention, being convinced that, of the fuel consumed in the ordinary processes of warming our houses and cooking food, at least one-third is uselessly thrown away, and might be saved by a more economical and scientific construction of common grates and fire-places. All useful and well-conducted experiments, therefore, in [p379] relation to these matters, deserve notice; and though much of Mr. Bull’s essay is not applicable to our case, it contains a variety of interesting facts and information: his experiments appear to have been very carefully conducted, and should be consulted by all those who are engaged in similar investigations.

_Meteorological Essays and Observations_. By J. Frederic Daniell, Esq., F.R.S. Second Part, 1827.

We hope to be able in our next Number to enter into a detailed examination of the subject of Mr. Daniell’s inquiries; at present, therefore, our object is merely to announce the second edition of his valuable and laborious essays, and the publication of the present _second part_, in which, for the convenience of those who possess the former edition, all the new matter is collected. It includes the following essays:—

1. On the Trade winds, considered with reference to Mr. Daniell’s theory of the constitution of the atmosphere; in a letter from Capt. Basil Hall, R.N., F.R.S.

2. On evaporation as connected with atmospheric phenomena.

3. On climate, considered with regard to horticulture.

4. On the oscillations of the barometer.

5. On the gradual deterioration of barometers, and the means of preventing the same.

6. Addenda and notes—among which will be found a valuable table of the elastic force of aqueous vapour, calculated by Mr. Galbraith from the experiments of Dr. Ure, by the formula of Mr. Ivory.

_Philosophical Transactions of the Royal Society of London, for the year 1827_. Part II.

The following are the contents of this Part of the Society’s Transactions:—

On a new form of the differential thermometer, with some of its applications. By William Ritchie, A.M., rector of Tain Academy. Communicated by J. F. W. Herschel, Esq., Sec. R.S.

On the structure and use of the submaxillary odoriferous gland in the genus Crocodilus. By Thomas Bell, Esq., F.L. and G.S.S. Communicated by Sir Everard Home, Bart, V.P.R.S.

On the permeability of transparent screens of extreme tenuity of radiant heat. By William Ritchie, A.M., rector of Tain Academy. Communicated by J. F. W. Herschel, Esq., Sec. R.S. [p380]

On the derangement of certain transit instruments by the effects of temperature. By Robert Woodhouse, A.M., F.R.S., &c.

On some of the compounds of chromium. By Thomas Thomson, M.D., F.R.S. L. and E., Professor of Chemistry, Glasgow.

Rules and principles for determining the dispersive ratio of glass; and for computing the radii of curvature for achromatic object-glasses, submitted to the test of experiment. By Peter Barlow, Esq., F.R.S., Mem. Imp. Ac. Petrop, &c.

On the change in the plumage of some hen-pheasants. By William Yarrell, Esq., F.L.S. Communicated by William Morgan, Esq., F.R.S.

On the secondary deflections produced in a magnetised needle by an iron-shell, in consequence of an unequal distribution of magnetism in its two branches. First noticed by Captain J. P. Wilson, of the Honourable East India Company’s ship Hythe. By Peter Barlow, Esq., F.R.S., Mem. Imp. Sc. Petrop.

On the difference of meridians of the royal observatories of Greenwich and Paris. By Thomas Henderson, Esq. Communicated by J. F. W. Herschel, Esq., Sec. R.S.

Some observations on the effects of dividing the nerves of the lungs, and subjecting the latter to the influence of voltaic electricity. By A. P. W. Philip, M.D., F.R.S. L. and E.

On the effects produced upon the air-cells of the lungs when the pulmonary circulation is too much increased. By Sir Everard Home, Bart., V.P.R.S.

Theory of the diurnal variation of the magnetic-needle, illustrated by experiments. By S. H. Christie, Esq., M.A., F.R.S.

On the ultimate composition of simple alimentary substances; with some preliminary remarks on the analysis of organized bodies in general. By William Prout, M.D., F.R.S.

_A Practical Treatise on the use of the Blowpipe in chemical and mineral analysis; including a systematic arrangement of simple minerals, adapted to aid the student in his progress in mineralogy, by facilitating the discovery of the names of species_. By John Griffin, Author of Chemical Recreations. Glasgow, 1827.

Performing with the blowpipe is something like playing upon the fiddle—it looks mighty easy, but for its perfect accomplishment requires a combination of skill and dexterity which practice alone can confer. We are disposed, therefore, to think lightly of those essays upon the subject which pretend to instruct the beginner in the actual use of the instrument; telling him how he is to puff out his cheeks, breathe through his nose, make a valve of his tongue, and keep up a [p381] perpetual stream through the nozzle of the tube; all which is much easier described than done, and is entirely matter of experimental acquisition, more easily attained without than with the usual instructions. In the little work before us, all these matters are passed over with fit brevity, and the attention of the student is chiefly directed to the appearances which different substances exhibit before the blowpipe, and by which minerals may be distinguished and classed. The history of these constitute the bulk of Mr. Griffin’s duodecimo, being preceded only by a few remarks upon the different kinds of blowpipe, respecting which we have merely to observe that justice is not done to Mr. Newman, who first suggested what is here called “Dr. Clarke’s blowpipe;” indeed elsewhere the author seems a little angry with Mr. Children for recommending Mr. Newman’s apparatus. We observe, moreover, that no notice is taken of Mr. Newman’s and several other papers on the blowpipe, which have appeared in the old series of this Journal; nor of Dr. Clarke’s original Essay, published in the second volume of that work, from which, and sundry other symptoms, we conclude that Mr. Griffin is a pupil of Dr. Thomas Thomson. Be this as it may, we bear him no malice, and very conscientiously recommend his book to the mineralogical student, as a valuable and clear epitome of what relates to the behaviour of substances before the blowpipe.

_Circle of the Seasons, and Perpetual Key to the Calendar and Almanack; to which is added the Circle of the Hours and History of the Days of the Week, being a compendious Illustration of the History, Antiquities, and Natural Phenomena of each Day in the Year_. London, 1828. Small 8vo.

The title of this book may lead our readers to suspect it as an interloper among works on science; but it touches upon many points of scientific inquiry, and upon botany especially, and is compiled with so much evident labour and accuracy, as to merit recommendation. The saints and festivals of each day are recorded, by which we make the acquaintance of many worthy persons and curious anecdotes; there is also a brief natural history of each day, containing short notices of the plants which on an average begin to flower or to fade, and of the birds which arrive or begin to sing. [p382] The merits of the descriptive poetry, which is thickly interspersed, we leave to other critics. Those who are destined to live in the “fuliginous tenebrosity” of this smoke-saturated metropolis, and to breathe an atmosphere “sated with exhalations rank and fell,” care little about the first peeping forth of the modest snowdrop, or the early bursting of the golden crocus; but such as reside in the country will be glad to have their attention pleasingly directed to the successive products of the field, the flower-garden, and the green-house.

_Conversations on the Animal Economy_. By a Physician. 2 vols. small 8vo. London, 1827.

We have more than once expressed our opinion on the subject of conveying information to young people in the way of “Conversations,” which in the present volumes are carried on between Dr. A., Harriet, Sophia, and Charles; they are at once instructive and amusing, and evidently the produce of one possessed of much information upon the subjects discussed, and, what is more to the point, of the art of pleasantly and intelligibly conveying it.

The Conversations open with an account of the coverings or integuments of animals; their arrangements by systematic writers are then adverted to, and a short but useful description is given of the varieties of mankind, as enumerated by Blumenbach and illustrated by Camper. The bones and muscles form the subjects of the fifth and sixth conversations; they are concisely described, and with sufficient accuracy. The brain and nervous system and the organs of sense are next talked about. The doctrines of phrenology are fairly explained; and in the conversations on smell and taste, vision, hearing, and touch, the anatomy of the respective organs, and their varieties in the different animal tribes are treated of, the dulness of the details being relieved by physiological illustrations. The remaining conversations are occupied with an account of the principal functions of animals, and of the several organs chiefly concerned in their performance; the varieties of teeth and stomachs are here treated of, and the structures of the heart and blood-vessels, as concerned in circulation and respiration. The production of heat by animal systems is then noticed; and the twentieth and concluding conversation is employed in the exposition of the general phenomena of growth and decay. [p383]

We have thus briefly stated the contents of these volumes, which are further illustrated by numerous woodcuts and several plates; and are perfectly ready to commend the performance as an extremely useful and proper book for young persons, but _not_, in our opinion, of both sexes: we should have been better pleased if Harriet and Sophy had been replaced by William and Thomas; for we cannot fancy the subjects here discussed as quite fit for young ladies. Boys, on the contrary, ought to know much more of these matters than they commonly do; and for conveying such information in a pleasing and familiar, yet neither vulgar nor superficial style, this compilation seems perfectly appropriate, and will, we trust, find, as it ought, a numerous class of readers.

_Notice of a New Genus of Plants discovered in the Rocky Mountains of North America by_ Mr. David Douglas. By John Lindley, Esq., F.L.S., &c. &c.

Upon his journey across the rocky mountains in April 1827, in latitude 52° N., longitude 118° W., at an estimated elevation of 12,000 feet above the level of the sea, the attention of Mr. Douglas was attracted by a brilliant purple patch amidst the surrounding snow. On approaching it, he was surprised to find that the colour which had arrested his eye was caused by the blossoms of a little plant, from which the superincumbent snow had not yet melted away. The well-known Saxifraga oppositifolia immediately occurred to his recollection, and he at first imagined he had either discovered that species, or one nearly allied to it; but upon a closer inspection, he perceived that it was no Saxifraga, but a genus apparently new. Specimens having been submitted to me for examination since Mr. Douglas’s return, the following description has been drawn up:—

The plant forms a thick tuft consisting of numerous perennial branched stems, the lower of which are covered with the persistent decayed leaves and fruit of previous summers. The _stems_ are round, bright purplish brown, covered with scattered, rigid, branched, short hairs, and densely clothed with opposite spreading leaves. The leaves are a dull glaucous green, semi-amplexicaul, [p384] linear, obtuse, about five lines long and three-quarters of a line broad, so closely covered with hairs like those of the stem, that the whole epidermis is hidden. Their veins are concealed by the hairs; but if the latter are removed, they appear to consist of a thickened mid-rib, and a few nearly simple spreading venæ primariæ. The _flowers_ proceed from the axillæ of the upper leaves, from three to six on each little branch; at first they are sessile, but their foot-stalks subsequently lengthen by degrees until the fruit is ripe, when they are from three-quarters of an inch to one inch in length, and covered with the same sort of hairs as the leaves and stem. The _calyx_ is hairy in like manner, obconical, angular, with five equal erect narrowly triangular teeth, about the length of the tube. The _corolla_ is of a vivid purple colour, infundibuliform, wholly destitute of pubescence; the _tube_ is a little ventricose and rather longer than the calyx, its whole length being about three lines; the _limb_ is spreading, five-parted with cuneate, oblong, obtuse, segments; the orifice is guarded by five transversely linear calli, placed under each sinus, and corresponding to the same number of external depressions of the neck of the tube. The _anthers_ are linear oblong, nearly sessile, opposite the segments of the corolla, and a little enclosed within the tube. The _ovarium_ is superior, of an obovate figure, one-celled, with a central, free, fungilliform placenta, the lower edge of which has five teeth corresponding to an equal number of peltate ovula; the _style_ is filiform, as long as the tube of the corolla, and continuous with the ovarium; _stigma_, a minute depressed cup. The _capsule_ is of a cartilaginous texture, surrounded by the persistent calyx; one-celled, with five recurving valves; the _seeds_ are two, peltate, oblong, convex on the outside, concave in the inside, dark brown, covered closely with minute dots or depressions; four only having been found, their internal organization has not been determined.

Hence it appears that, with the exception of the interior of the seed, the whole structure of the plant is determinable: it is also obvious that it is referable to Primulaceæ, of which it possesses all the characters. In fact it is closely akin both to Primula and Androsace. From both these genera, however, [p385] its ovarium which exhibits the greatest instance of reduction of ovula yet known in the order, and its dispermous capsule, with oblong concave seeds, readily and essentially distinguish it.

I have, therefore, named it after its indefatigable discoverer, whose active and successful researches in its native country, richly entitle him to the distinction.

DOUGLASIA.

NAT. ORD. _Primulaceæ_; _inter_ Primulam _et_ Androsacen.

_Calyx_ obconicus, angulatus, 5-dentatus. _Corolla_ infundibularis, tubo ventricoso, limbo plano 5-partito, fauce callo lineari sub utroque sinu. _Ovarium_ uniloculare placentâ centrali liberâ pedicellatâ fungilliformi, margine 5-dentato; ovula 5 dentibus placentæ opposita. _Capsula_ vestita, unilocularis, 5-valvis. _Semina_ duo concava scrobiculata.—Cæspes _suffruticulosus_ (Americæ borealis), foliis _indivisis_, pube _rigidâramosâ_, _floribus axillaribus solitariis_.

Sp. 1. _Douglasia nivalis_.

_A Description of the Aurora Borealis seen in London on the Evening and Night of the 25th of September, 1827; with Critical Remarks upon other Descriptions of the same, and previous Appearances of the Meteor, both in the Northern and Southern Hemispheres_. By E. A. Kendall, Esq., F.S.A.

On the evening and right of the 25th of September last, the horizon of the metropolis, toward the north, and toward the north-west and the north-east, exhibited a remarkable display of the meteor or phenomenon called, after the example of the Italian philosopher Gassendi, Aurora Borealis.

The weather, for many days preceding, had been mild, with alternate sunshine, clouds, and showers. The wind had been generally in the west and south-west quarters; though on the 18th and 19th it was in the north-west, and on the 20th in the north-east. The barometer, at three o’clock in the afternoon, had stood at from 30° 40′ to 30° 20′, to which latter height it had descended on the 20th; and, from that day to the 25th, it had remained, at 29° 90′ and 29° 75′. The thermometer, at the same hour, between the 14th and the 20th, had ranged between 65° 6′ and 59° 2′; and it stood, on the 25th, at 59° 6′, with the wind in the south-west. The sky, toward the zenith, on the evening of that day, was [p386] partially clear, and partially covered with shifting clouds. On the north, and on the west and east of north, heavy and stationary clouds blackened the whole horizon, to an elevation of more than five degrees; and the southern hemisphere was dark with dark clouds from the horizon to the zenith.

* * * * *

I. By some, the Aurora was seen from the time when the sun was set; but the first appearance in the heavens, which attracted the attention of the present writer, whose situation at the moment shut out from him the horizon upon all sides but the west, was that of a certain breadth of red or copper-coloured light, or of light of a colour nearly resembling that reflected by an ordinary conflagration of buildings, pointing upward from the west. The colour, indeed, was dissimilar from that which is usual upon the occurrence of a fire on a cloudy night; yet, in the absence of any other immediate explanation, he should not have hesitated so to understand it, except for the figure within which it was circumscribed, and which, instead of being diffusive, and less and less conspicuous toward its extremities, or rounded in its outline, like masses of ruddy smoke, had the peculiarities of an equal breadth, rectilinear sides, a square top, and sharp outlines. Its height was continually increasing; but not even that phenomenon, nor even the curve to the eastward, across the heavens, and which it presently began to add to its figure, were appearances absolutely to dissipate the illusion of the existence of a fire; and it was scarcely, therefore, till this breadth of colour, throwing itself entirely over the heavens, and descending, at its projected extremity, toward the east, formed an arch, of which, perhaps, the elevation was seventy degrees, (which was not the work of many minutes, the motion, at the same time, being visible, but of moderate rapidity,) that its real character of a natural phenomenon distinctly impressed itself upon the mind of the present writer, its observer. While this, however, was proceeding, the road which he was pursuing had brought him more into view of the north-western and northern horizon; and, then, the light in the north, and to the west of north, which, from behind the clouds that lined the horizon, seemed like the light of a rising moon, or of the [p387] breaking day, together with the vertical projection of rays of light, beneath and above the arch, removed every doubt as to the cause of the appearance, by demonstrating its connexion with an Aurora Borealis.

It was now about a quarter past eleven o’clock. The sky, beneath the lower or inner edge of the arch, was clear and star-light, and, through the contrast created by the ruddy colour placed against it, appeared of a lively blue. The upper edge of the arch, in the meantime, was relieved only by the dark gray of the clouds, which, with more or less continuity, overhung the upper part of the heavens. But these latter were now dispersing; the cloudless zenith, which presently afterwards disclosed itself, was now progressively and swiftly preparing; and, as the clouds moved and fled, the outlines of the arch lost their sharpness, the colour changed, from that of fire or of copper, to something more or less of purple or of the rose; it spread itself in the vapour, and with the vapour vanished.

* * * * *

II. But this was only the curtain of the stage, behind the folds of which the true scene had its existence. This latter, still concealed, to a certain and uniform height, by a parapet, as it were, of dark and unbroken clouds, consisted, first, in the ground of white light, already described as resembling that of a sky in the midst of which clouds shut out the disk of the moon, or rather that in which the rising sun is just about to appear; and, secondly, in a range of columns, or fountains, or jets of light, more coloured than the ground, which, rising from behind the ridge or parapet of clouds, and from and in the midst of the white light, formed, together, not the figure which would have been produced by their uniform convergence toward the zenith, but one which bore some resemblance to that assumed by the sticks of a fan, or still more to the appearance of stalks in a flower-basket, or in a sheaf of corn. For, in this manner, the column, which, in general terms, may be called the central one, and which arose in the due north, was vertical, and therefore projected toward the zenith; while those which extended from it upon either side, that is, toward the west or toward the east, gradually inclined more and more [p388] toward the horizon on their respective sides; and, as to the outer columns on the east, inclined, not in rectilinear figures, but in curves more or less decided. In these columns or coruscations several particulars were to be remarked.

1. That, within the space of from one hour to two, the whole group appeared to traverse the horizon together, from the west of north to the east of north, as if upon one movable base, or as if the source of their appearance became gradually exhausted to the west of north, and grew gradually into activity upon the east of north; alternatives of explanation, however, which might materially affect the theory of their production. During the whole change, in the meantime, the north preserved its splendour, appearing uniformly as the focus of the fire, or as the pivot of the machine, or as the well from which all else was supplied. The change consisted in the appearance of columns, of more or less magnitude, strength, and brightness, more or less advanced from the north toward the west, or from the north toward the east; but the north, during all this variation, suffered no other change than this, that whereas, in the beginning of the evening, the greater portion of columns rose to its west, while, in the latter part of the night, the greater portion arose to its east. But, besides this general configuration, and this united motion of the meteor, there was to be observed, in the several columns themselves, both the variations of colour which distinguished one from another, and the irregular and independent movement of each, always in the direction of its length or altitude, and situate in the interior, as it were, of its body; and also that peculiarity of form which distinguishes these coruscations from all other luminous appearances.

2. The colours of the columns, in that part of their height which is nearest their base, and where, as a ground, they had only the white light of the horizon, by which, and by their motion, and it should, perhaps, be added, their vividness, they were distinguished, is a point upon which the writer speaks with some hesitation, and with respect to the more close observation of which he could like to enjoy a second opportunity of beholding the phenomenon. The variety and richness, and sometimes the terrible grandeur, of the colours [p389] exhibited in the Aurora Borealis, is the constant theme of spectators and naturalists; and, upon the late occasion, an observer, apparently of more regularly scientific habits of pursuit than himself[120], has particularly insisted upon a column, of a violet colour, rising west of north, and the place of which he thinks corresponding with that of the _magnetic pole_; a coincidence from which, as it may seem, he would believe a confirmation of the _magnetic theory_ of the production of the Aurora to be obtained. In setting down the present description, the writer tasks himself to the most faithful description of what he actually saw, and suppression of all desire to support or condemn a theory, of which his mind is capable; and by those rules, therefore, the whole statement will be guided. His description already differs from that of some of his fellow-witnesses, as will be expressly considered below; but he confesses that while, in point of persuasion, he much inclines to the idea, that all the light displayed by the Aurora is in itself white, and only tinctured to the eye of the spectator by the atmospherical medium through which it is seen; and while, with respect to all those deeper colours, whether crimson or purple, or blood-colour, which appal the superstitious, and are described by the picturesque narrator as exhibiting the terrible in matters of vision, he judges it supposable that the whole machinery consists in the same interposition of vapour, near the horizon, which so often gives to the sun and moon themselves the appearance of being coloured like blood: while, therefore, he still adheres to his opinion, that the colours ascribed to the Aurora are wholly extrinsic; and, to borrow the words of a scientific writer, “dependent upon the medium through which they are seen;” he is obliged to acknowledge, that it did appear to him, that the several columns, in truth, were yet variously coloured, of pale, but bright and pleasing colours, from a pale yellow to a pale pink and a pale violet, and this in the direction of their height or length,—a phenomenon which wholly excludes, as to those columns and their colours, the influence of an interposing medium, the effect of which would be perceived horizontally, and across the whole range of columns, or part of the range, and not [p390] vertically nor obliquely, according to the direction of each column, and within the limits of its sides. He confesses, also, that he did take notice of the pale, but bright violet-coloured column, distinguished also by its breadth and height, and situated to the west of north; but which column, he is surely right in adding, ultimately moved, with those next to it, toward the north. He distinctly and pointedly observed, at the same time, that the columns which stood due north were always white, and that the colours of the other columns appeared to strengthen in proportion as they were distant from the due north, either west or east; and he came to a fixed conclusion, while the phenomenon was under his eye, that, to his judgment at least, the strength of the fire, so to say, was in that point of the horizon which lay due north; and that there was a diminished brightness, with a proportionable increase of colour, to the right and left.

3. As to the separate movements of the columns, these, in the first place, were quick, and forced upon the eye, while the movement which gradually deployed or advanced the right wing of the celestial arm, and gradually contracted or withdrew the left, was slow, and perceived only by its results; and, in the second place, while these latter were parallel to the horizon, the former were either vertical, or in the oblique or curved direction of the bodies of the columns. But this motion consisted either in vibration, or in irregular but alternate projections and contractions; and the motion of each column, as has been said, was independent on that of others. Rarely, two adjoining columns were in motion at the same time. Almost always the moving column or columns were seen to start from the midst of others, which, for the time, were quiescent, but which had had their turn before, and would presently have it again. What eminently struck the writer, however, was the internal motion of that to which he cannot allow himself to give another name than that of the apparent luminous material of the columns. It seemed to him as if the volume of each column or coruscation was itself composed of parallel lines of luminous matter, arranged in the direction of the column, and every one of which was separately the subject of movements similar to those of the entire [p391] column, or entire bundle of lines; or as if the whole column were like the stalk of a plant, and filled with upright and luminous fibres, or like a skein of thread, drawn vertically or obliquely, and of which each particular thread should have particular motion in the direction of the whole; or (what he thought the comparison which proclaimed the very nature of the material of the columns) like fountains, or jets of water in the sun, in which every particular particle should be moving in the general direction of the jet, and yet each moving and shining for itself.

4. And this apparent nature of the substance of the columns or coruscations allies itself to what finally regards them; namely, their form. In this description, they have hitherto been spoken of by the name of columns or pillars; and the similitude, which that name suggests, is justified by the general figure of all the lower parts of their bodies, which, unlike the figure of rays of light on the one hand, and unlike that of flames of fire on the other, is a tall or lengthened object, of small comparative diameter or breadth, and of which the sides consist in right and nearly parallel lines. But, by the English, these columns, pillars, or coruscations, were anciently called so many _burning spears_; and they have also received the names of _streamers_ and _pencills_[121], which two latter, in the history of appurtenants of war, signify long and narrow, and pointed banners or flags. Their similitude to flags is excusably fancied from their quick, capricious, and irregular motions, but their likening to “spears,” is that which may claim to be thought the most felicitous, as to the true conception of their form, as it is also that, the idea of which contributes to render the phenomenon the most fearful in the [p392] survey of ignorance and superstition. But the SPEAR-SHAPE is descriptive, because the coruscations, unlike rays of light, and unlike flames of fire, have neither the obtuse figure of a pyramid, nor the acute one of an obelisk, upright or reversed; but, after rising, through almost their whole height or length, of an equal or nearly equal diameter, terminate in a point which is formed, not of right lines, like the point of a dagger, but of curved lines, so as to form the rounded point of a spear, or that figure which is so familiar to botanists, as spoken of “spear-shaped” leaves. A ray of light, in whatever direction it is thrown, broadens, with right-lined sides, from the first point of its departure, to the furthest stretch of its projection; a flame of fire points uniformly upward, with the same regularity of form, excepting only as it is liable to undulation from the motion of the atmosphere; but, the columns, spears, streamers, or coruscations of the Aurora Borealis, have no form but that under review.

5. About half-past eleven o’clock, or nearer to twelve, several powerful columns shot toward the zenith; while, to the east of north, others were at once curved in their form, and projected in an angle of about thirty degrees with the horizon. But while, upon the west of north, the sky, above the ridge of clouds, was entirely clear, so that, there, the columns played upon a ground which formed a slight contrast with themselves, here, the clouds were still heavy, and the columns behind them appeared, in consequence, of a fiery red, deepening as they approached the outer edge of the whole display, at which was the sharpest outline, contrasted in the distinctest manner with the dark sky. The light upon that side called to the mind of the writer the “dunnest smoke of hell,” of Macbeth; while, as to its outer line, as seen from the east end of Pall-mall, the sides of the stone spire of St. Martin’s church, which rose to the eastward of it in the sky, were not more sharply defined; the dark intervening sky affording relief to both, though not equally so, upon account of the superior brightness of even the obscured columns. But, in taking leave of this columnar, or spear-like, and main part of the Aurora, it may be permitted to add, that, in those tapering forms, together with their motions, (though the comparison [p393] may still be sufficiently remote and fanciful,) it was easy to discern the origin of their having been resembled to weapons of war; that is, to the spears of an army, raised, lowered, laid at angles, and gleaming, glittering, crossing, and clashing in battle. And equally, too, from their quick, varied, and separate, and, as it were, whimsical motions, might they reasonably receive, in their milder displays, and in moments of more peaceful and cheerful association, the very different name of _merry dancers_!

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III. Though, as will presently be found, it is the ruling idea of the present writer, that the Aurora Borealis is a single object, its appearance, when unmodified by the accompaniments of clouds or fogs, being merely that of its own coruscations, playing in the free expanse, yet for the purposes of analytical description and contemplation, it is here thought convenient to divide it into the three parts in which, through the temporary and accidental intervention of the coloured arch before-mentioned, it appeared in the night now in recollection. These three supposititious parts, then, may be understood as follows: first, the arch, belt, or band which was temporarily thrown across the heavens; second, the main body of the coruscations below the arch; and third, the coruscations above it, and in or near the zenith. It is of these only that it remains to speak.

It was not till about midnight that the zenith itself (which, however, formed the southern boundary to this part of the display) became the scene of a class of appearances, differing, indeed, essentially, in their forms, from those in the horizon, but closely connected, as it may be believed, with all the materials, and all the movements, of these latter. The zenith, at that hour, was cloudless, and resplendent with stars, and the air was freshened by a gentle breeze from the south. Between the earth and the stars above, there was no apparent intervening vapour, and nothing, therefore, save that atmospherical fluid which eludes the sight. But, through that medium, if such only it was, coruscations were now continually shooting, of which the appearance was, that it overspread this portion of the vault of heaven with an ever-shaken [p394] sheet of thin, gauzy, white, or yellowish-white, and nebulous, or cloudy matter. To the writer, this superior portion of the Aurora, though not the most lustrous, and, therefore, not the most striking of the whole, was yet by no means the least interesting and inviting to attention; for, here, as its appeared to him, the _material_ and the manner of operation of the meteor were brought nearer to the eye, and exhibited with such a back-ground (the starry heavens) as gave a transparent view of the same matter as that, which, (as he thought,) seen vertically, and in the horizon, appeared comparatively, at least, opaque. The transparent medium, however, above, through which, even when shook or vibrating, and even when whitened with light, the stars were always seen in more or less brightness, was now in continual motion; or, meteoric light or matter was continually, though irregularly, and as it were, playfully shot through it. The illuminated substance (whether the atmospherical fluid, reflecting the light of the meteor, or the luminous body of the meteor itself, but probably the latter) was incessantly discovering itself in different places; now here, now there, now bright, now dim; but far less in a manner, or with an appearance, such to be compared with lightning, than with such as resembled the changes of ripple upon the bosom of a wide-spread water, when a variable breeze blows over it; first in one part, and then in another; and now in one direction, and the next moment in a second. Or, the canopy of heaven, at this time, might be said to be composed of a lace or gauze bearing a figured pattern, of which the fluttering motion continually changed the places, or hid or re-displayed the figures represented; or the picture, perhaps, will be more easily imagined, if conveyed in the very appropriate language of an older hand, which, referring to the appearances displayed in the zenith, remarks, “They break out in places where none were seen before, skimming briskly along the heavens; are suddenly extinguished, and leave behind a uniform dusky track. This, again, is brilliantly illuminated in the same manner, and as suddenly left a dull blank.” It should be understood, however, that, at least as seen by the present writer, in this mixture of white and blue, the blue was always the preponderating colour; or, in other words, [p395] that, the field of the unoccupied zenith always bore a large proportion to the space or spaces covered, however momentarily, with light, or with the luminous substance. For the rest, the particular mentioned in the passage which has now been quoted, namely, that of the residue of a dusky track, after the departure of the white light, did not, if it was there, attract the attention of the present writer, upon the late occasion; but he certainly, in many instances, remarked the return of the light to the places in which it had been visible before; and this feature, either with or without that of the continuance of a dusky track, is possibly capable of adding some support to the general opinion which he conceived at the moment, which all subsequent information has still allowed him to retain, and of which he proposes to make further use; namely, that the appearances in the zenith are only extended exhibitions of the luminous phenomena in the horizon, or their southern extremities, or the tops of columns projected from the northward. He thought that, in the zenith, he saw the same material, parcelled out, attenuated or diluted, spread thin, and, as it were, shown with greater transparency, with that which, in thicker volume, with more accumulated strength, intenser light, with more solid body, and withal behind a denser mass of atmospherical vapour, arose, and glowed, and sometimes gloomed, in the horizon. But, be this as it may, it is, perhaps, this upper part of the exhibition, in which the lights or streamers seem to interweave, or cross and recross each other, to dance in and out of the area, and to indulge in motions still more capricious or anomalous than is probably the real fact; it is, perhaps, this upper part which has alternated, as before recalled to view, the names and similitudes of spears, gleaming, glittering, interposing and clashing as in battle, and of _merry dancers_, the latter the gayer comparison of the dancing north.

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IV. The Aurora continued to fix the attention of the writer till between twelve and one o’clock of the morning of the 26th; and he presumes that it continued visible till the superior light of the rising day eclipsed its glory. The 26th was warm, but oppressed with fog, through which the sun broke [p396] only at intervals; and, between four and five o’clock in the evening, a small but steady rain commenced, and continued, or rather increased in heaviness, till after midnight. Between eleven and twelve, while it still rained, the writer, on looking at the sky, which was covered with a uniform mass of clouds, the writer observed, from point to point, over the northern and southern hemispheres, a glow of ruddy light, which he suspected, and still suspects, to have been produced by the light of the continued Aurora, reflected by the vapour. He took the opinion of a fellow-traveller, which coincided with his own; but it has not come to his knowledge that any individual, himself and his companion excepted, has formed a similar conjecture—nor, indeed, is it impossible that it was no more than the light of the hidden moon. The night of the 27th was star-light, though with fog near the surface; and there was then no appearance of an Aurora. The night of the 28th was remarkably clear, and there was still no return of the Aurora. The morning of the 29th was warm, with continued and heavy rain; but, after this, there succeeded a week or more of clear and dry weather; and these united particulars close the history of the phenomenon, as far as belong to the personal observation of the writer. The direction of the winds, and the state of the barometer and thermometer, were of the same general description, during many days subsequent to the appearance of the Aurora on the 25th, as that which had belonged to them from the 20th, and almost for many days before, and of which the particulars have been stated above; and these remarks may merit record, as connected with the question of the ordinary duration of the Aurora, and of the weather by which it may be thought produced, or which it may be thought to bring. In many instances, it has been observed, even in its splendour, and even in southern latitudes, for several nights in succession; and an influence upon the weather has likewise been expected from its appearance. Upon this occasion, there was no remarkable change in the latter till the night of the fourteenth day after the Aurora (October 10th), when there occurred a violent gale of wind from the south-west, accompanied with loud thunder, and the most vivid lightning; subsequently to which, as usual, [p397] the air, for a few days, was felt to be cooler than before. It has been said, that a gale of wind, from the south-west, is always to be looked for within twenty-four hours after the Aurora.

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V. The astronomical writer, already more than once mentioned, speaking of the Aurora of the 25th of September, describes it as “that mysterious phenomenon;” and Mr. Adams, the meteorological correspondent of the publication referred to, records it as, “perhaps, as conspicuous as any that has ever been seen in England[122];” so that, assuming these impressions in both instances to be well founded, neither the present state of science upon the one hand, nor the specimen of the phenomenon upon the other, are such as to discourage either of the objects of the remainder of these pages; namely, the one to contribute, as fully as possible, to the completion of a faithful account of the Aurora, as seen in London upon the late occasion, by uniting, and by analysing the descriptions that have caught already the eye of the writer; and the other, to correct, and to enlarge if it should be practicable, the natural history of this description of meteor, by the comparison of what has hitherto been usually written upon the subject, either descriptively or philosophically, as well with the results of the late actual observations, as with the several facts or opinions more anciently registered. According to some, the interval which had elapsed, since an equal or a superior display of this phenomenon was witnessed in London, is twenty-four years, and, according to others, thirty-six; nor is the scanty list of examples scientifically recorded, at all inconsistent, from the wide separation, as well as irregularity of its dates, with such a view of the infrequency and uncertainty of any considerable appearance in other southern latitudes. The opportunity, therefore, now offered, ought not, perhaps, to be neglected; and the writer is not wholly without the prospect, that, upon a re-examination, both of opinions and facts, some safe and inevitable conclusions may be elicited, both as to the history and the theory of the meteor, hitherto, the one hastily received, [p398] and the other negligently overlooked, or unwarrantably contradicted. The paragraphs, then, which immediately follow, will connect and review the accounts of the writer’s fellow-observer of the 25th of September; while those which succeed will be devoted to a brief enumeration of statements already recorded in books; though, to a certain extent, both these paths will involve us in mixed investigations, historical and theoretical.

1. “It first appeared,” says Mr. Adams, who dates from Edmonton, in Middlesex, “about eight o’clock in the evening, as a strong white light, much resembling the approach of sunrise; and so continued till a short time after eleven, when a considerable number of dark clouds collected toward the north and north-west, and several streaks of a pale white light were seen proceeding from the clouds, and reaching nearly to the zenith. But the most remarkable part of the phenomenon was exhibited in a N.N.E. direction, where, at about 30° above the horizon, was a small dense cloud, above which was a broad streak curved, and about 10° in length, varying in colour from a deep copper hue to a red.” “From this,” continues Mr. Adams, “the coruscations were incessant, and remarkably bright, darting frequently to the zenith, where they were frequently crossed by others equally bright and numerous, proceeding from the west toward the east.”

2. The astronomical writer, who dates from Deptford, describes the phenomenon as commencing at a quarter past eight o’clock, and travelling, from west and north-west, to north-east; and the streaks, or streamers, or, as he denominates them, the flashes, “converging to the zenith,” and “coruscating with great velocity.” He also particularises the peculiar appearance of “a streak or column of a phosphorescent violet tinge;” and adds, “The _two_ red beams of light, seen in the _easterly_ and _westerly_ direction [directions], were diametrically opposite to each other, and ninety degrees distant from the violet light (by far the most luminous, though comparatively quiescent) which was to the west of north, _and therefore could not be far from the magnetic meridian_, which would be crossed at right angles by a line joining the places of the red beams. The southern edges of these were accurately defined, not blending with the adjacent azure, but most distinct from it, and [p399] perpendicular to the horizon.” Finally, this gentleman speaks of the general luminous aspect, as “much resembling the tail of a comet,” and says, that Ursa Major, and other stars, were visible through its medium; that three meteoric stars also appeared, during the phenomenon, in the east and north-east; and that the entire horizon was obscured by dark, heavy clouds, from three to five degrees in height[123].