color up to about 11 o'clock, when the whole northwestern part of the heavens was a brilliant red, reaching to the zenith, the color fading gradually to the north to a strong white light, and then rising again in the northeast, but not so brilliantly as in the northwest. At this time (11 p. m.) I came to the office and had one of our lines disconnected from the batteries and the ends grounded at Harrisburg and Philadelphia. This arrangement gave a current a trifle stronger than the regular batteries and in the same direction, galvanometer deflecting to the right. At 11.45, after one or two breaks, the current changed, the galvanometer needle deflecting to the left; at 11.55 back to the right; at 12.10 to the left, where it remained until 1 o'clock, when I went home. After the galvanometer needle deflected to the left, at 11.45, the current became very unsteady and weak; was only sufficiently strong to move the relay for a few minutes at a time. The galvanometer showed a current of varying strength all the time. Sunday, September 25th, the aurora again appeared about 8.30 p. m., but not near so brilliant as on the former evening. I had a wire connected as before, viz, to the ground at Harrisburg and Philadelphia. This produced no effect whatever on the relay. The galvanometer at 8.40 deflected to the left; 8.45, right; 9, left; 9.20, right; 9.21, left; here the current was very changeable, the needle fluttering from side to side; at 9.22 again to the right, where it remained until 10 p. m., when I went home. The galvanometer I have is Dr. Werner Siemen's universal galvanometer. [The change in direction of the current may possibly have been due to the greater action of a beam of the aurora on the easterly part of the wire between Harrisburg and Philadelphia, and afterward of another beam on the westerly part of the wire. It is therefore important to note whether a change of a similar kind takes place in a wire extending north and south.-J. H.] METEOROLOGY. NEW CLASSIFICATION OF CLOUDS. BY PROFESSOR ANDRE POLY, Late director of the observatory at Havana. HISTORICAL SKETCH. The meteorologists of antiquity felt the need of distinguishing the different appearances of clouds, but were, at the onset, completely bewildered by the great variety of form which they assumed, apparently without order. Aristotle* first studied the phenomena of clouds in relation to their optical properties-their power of reflecting and refracting light, and the production of rainbows, halos, and coronas. Theophrastus, his disciple, afterward vaguely observed the forms of clouds relative to the predictions of change of weather. He remarked, for example, that the appearance of straight horizontal layers of clouds on the summits of mountains is an indication of wind and rain; but these attempts evidently must have failed, because the natural classification of objects in the time of Theophrastus was unknown. It was not until 1801 that the great naturalist Lamarck, ‡ and in the year after the celebrated English meteorologist Luke Howard, § perceived the possibility of referring the clouds to some fundamental types, following the example of the natural classification for living beings adopted by Linneus. Lamarck, who pointed out the importance of the study of the forms of clouds, determined six principal types, which he denominated clouds en balayures, * ARISTOTLE. † THEOPHRASTUS.-Liber de ventis, et opuscula de signis pluviarum et tempestatis, auct. Theophrasto, in lat. vers. et illustr. apud Franciscum de Franciscis Bonaventura, Venetiis, 1594, 4 parts, 1 vol., 4to; Eresii Theophrasti qua supersunt opera et excerpta Librorum quatuor tomis comprehensa Jo. Gottlob Schneideri, Lipsiæ, 1818-21, 5 vol., 8vo, vol. ii, pp. 466-476, 599-605; vol. iv, pp. 719-756; vol. v, pp. 163–173. ‡ LAMARCK.—Annuaire meteorologique, Paris, an x, No. 3, p. 149; an xi, No. 4, pp. 126-128; an xii, No. 5, p. 159. § HOWARD.—Tilloch's Philosophical Magazine, 1803, vol. xvi, pp. 97–107, 344–357; vol. xvii, pp. 5-11, pl. vi, vii, viii, with some changes not affecting the nomenclature in Ree's Cyclopædia, 1819, vol. viii, art. cloud; in Nicholson's Philosophical Journal, 1812, vol. xxx, pp. 35-62, without plates; in supplement to the Encyclopædia Britannica, 1824, vol. iii, pp. 202-205, art. cloud, with plates, and the addition of a set of new terms for the modifications, intended for the use of English readers; The Climate of London, London, 1833, vol. i, pp. xxxix-lxxii; On the Modifications of Clouds, and on the Principles of their Production, Suspension, and Destruction, being the substance of an essay read before the Askesian Society in the session from 1802 to 1803, issued separately, in 1832, London. 8vo., without plates; id, London, 1864, in 4to, with lithographs. (sweeping;) en barre, (bars;) pommelés, (curdled;) groupés, (grouped ;) en voile, (veil;) and attroupés, (piled.) The year following, 1802, Luke Howard proposed a classification of clouds still more elaborate than that of Lamarck. It is a remarkable fact that these two savants, who labored independently of each other on clouds observed in two different countries, should have arrived at almost the same fundamental types, and especially at the determination of the same clouds, though designated by different denominations. Thus, in the seven types which Howard has established, we find the first five types of Lamarck, according to the following table: Types of Lamarck. En balayures, (sweepings). En barre, (bar) Pommelés, (curdled). Groupés, (grouped).. En voile, (veil) Types of Howard. Cirro-cumulus. Cumulo-stratus. ... Nimbus. As to the two other clouds of Howard, the stratus being but a mist, and the cumulus corresponding entirely to his own cumulo-stratus, since he made double use of these identical forms, we see how the five true types of Howard are fundamentally the same as those of Lamarck. If we consider that my new type of fracto-cumulus is found in the classification of Lamarck under the name nuage attroupé, (piled cloud,) adding besides my two other types of pallio-cirrus and of pallio-cumulus, the last being a modification of Howard's nimbus, we have the classification of clouds established by me in 1863, which I shall describe in the following exposition. The types which served as the base of Howard's nomenclature were very happily chosen, since, as Kämtz well observed, they are connected with anterior atmospheric changes, and consequently furnish us with indications of approaching change of weather. Howard in his classification, which is almost entirely based upon the form of the clouds, distinguishes three simple modifications: The cirrus: parallel flexions, or diverging fibers, extensible by increase in any or in all directions; the cumulus: convex or conical heaps increasing upward from a horizontal base; the stratus: a widely extended, continuous, horizontal sheet, increasing from below upward, from which the two following intermediate modifications are derived: The cirro-cumulus : small, well-defined, roundish masses in close horizontal arrangement or contact; the cirro-stratus: horizontal, or slightly inclined masses attenuated toward a part or the whole of their circumference, bent downward or undulated, separate or in groups consisting of small clouds having these characters; and, finally, the two following compound modifications: The cumulo-stratus: the cirro-stratus blended with the cumulus, and either appearing intertwined with the heaps of the latter, or superadding a wide-spread structure to its base; the cumulo-cirro-stratus vel nimbus: "The rain-cloud, a cloud or system of clouds from which rain is falling. It is a horizontal sheet, above which the cirrus spreads, while the cumulus enters it laterally and from beneath." I shall point * out below the faulty interpretation which has been given by all the writers to the description of Howard's two types of clouds, the stratus and nimbus, then the defects of this nomenclature, which I reject, and the new classification which I substitute, although since the time of Howard no other classification having been hitherto proposed, the following are some partial attempts which have been made on the subject. In 1815 Thomas J. M. Forster reproduced, with some remarks, Howard's description of clouds, adding an English nomenclature of common names. In 1817 A. Müller† proposed the removal of some obscurities in Howard's descriptions, founded upon observations which he had carried on for twenty years at Vienna, in the north of Germany, upon the northern and southern slopes of the Alps, on the banks of the Rhine, and in France. In 1832 the celebrated meteorologist Kämtz‡ determined a new form of clouds under the name of strato-cumulus, or night clouds; that is to say, the reverse of Howard's cumulo-stratus. But before his death, M. Kämtz himself acknowledged to me that he no longer attached any importance to his strato-cumulus, and that I could erase it from the nomenclature of couds. In 1857-58 W. S. Jesons§ published two notes upon the form of cirrus and other clouds. He endeavored to account for their formation by laboratory experiments, which he had made with vapor of water. In 1863 the lamented Admiral Fitz Roy,|| having in charge the meteorological department of the Board of Trade, (London,) proposed the adoption of an augmentative termination in onus, and a diminutive in itus, to the nomenclature of Howard, in the following manner: From cirrus he forms cirronus and cirritus; from cirro-stratus, cirrono-stratus and cirrito-stratus, and so on. Not only does this modification refer to the less or greater quantity of clouds without changing the primitive form, but it is subject to great error in practice without being warranted in this by either the observation or the plates of Fitz Roy. Finally, in 1863, I proposed to the Academy of Sciences of Paris the determination of the new types, which I have named pallium (pallio-cirrus and palliocumulus) and fracto-cumulus, the description of which will be found farther on. When one considers the imperfection of Howard's old classification, tho difficulties of distinguishing each stratum of clouds, FORSTER.-Untersuchungen über die Wolken und andere Erscheinungen in der Atmosphäre, Aus. d. Franz, 2. Auflage, Leipzig, 1819; Researches about Atmospheric Phænomena, London, 1815, 2d edition, pp. 1-113; id., London, 1823, 3d edition, pp. 1-113. + MÜLLER.-Gilbert's Annalen der Physik, 1817, vol. lv, p. 102; Bibliothèque universelle de Génève, 1817, vol. v, pp. 6–12. KÄMTZ.-Lehrbuch der Meteorologie, Leipzig, 1831, vol. i, p. 377; Vorlesungen über Meteorologic, Halle, 1840; id., translated by Ch. Martins, Paris, 1843, p. 115, pl. iii. JESONS.-Philosophical Magazine, 1857, vol. xiv, pp. 22–35; 1858, vol. xv, pp. 241-255. || FITZ-ROY.-The Weather Book, London, 1863, p. 391, pl. ix, x. ¶ Poty.—Sur deux nouveaux types de nuages observés à la Havane, denommés pallium (pallio-cirrus et pallio-cumulus) et fracto-cumulus-Comptes-rendus de l'Académie des Sciences de Paris, 1863, vol. lvi., p. 361; Annuaire de la Société Metéorologique de France, 1863, vol. xi, p. 53. with their corresponding elements, and especially the considerable length of time that an observatory must spend in making a good observation, according to our present faulty method, we are less surprised at the little progress that a study so interesting has hitherto made. I must add an important fact, which has passed completely unnoticed: that the classification of Howard also is faulty in the definition of stratus and nimbus. Kämtz's treatise on meteorology gives the following definition of stratus, which has been since blindly adopted by all meteorologists: "It is a horizontal band, formed at sunset and disappearing at sunrise." On the contrary, Howard's definition has always been that the stratus "is the lowest of clouds, since its inferior surface commonly rests on the earth or water; this is properly the cloud of the night, the time of its first appearance being about sunset. It comprehends all those creeping mists which, in calm evenings, ascend in spreading sheets (like an inundation) from the bottom of valleys and the surface of lakes, rivers, and other pieces of water to cover the surrounding country." In continuation, Kämtz, describing the cirrono-stratus, remarks that "these clouds form horizontal strata, which, at the zenith, seem composed of a great number of thin clouds, while at the horizon, where we perceive the vertical projection, we see a long and very narrow band." Thus for the stratus we have a horizontal band, and for the cirro-stratus at the horizon another band, long and very narrow. According to this savant, between these two bands there is no distinctive mark save the hour at which they appear. But as the bands cirro-stratus are frequent exactly at the rising or setting of the sun, it is very difficult to distinguish these two orders of clouds. It must be added that the cirrus and the cirro-cumulus show a tendency to dispose themselves in bands parallel with each other, which at the horizon may be equally confounded with those of stratus and cirro-stratus. As to the origin of the stratus can we, without confusion, give the name of cloud to a phenomenon already designated as mist? The sole connection which exists between a cloud and a mist is in the first precipitation of vapor of water in the atmosphere, and its greater or less condensation. It is when the mist is elevated to the region of inferior clouds that it is condensed under the form of a cumulus, and the visible vapor of water takes its first forms. Hitherto the mist was but a shapeless mass of vapor molded, so to speak, by the accidents of the earth and sheets of water, and following the permanent or transient outlines of these surfaces. It seems that Howard's first error was calling a mist a cloud, and the grave responsibility rests upon his successors of giving the mist of this writer as a true cloud under the form of a horizontal band. This error has been extended to the different plates published in 1815 by Forster, in which, nevertheless, the stratus is not given as a band, but rather as a mist raised at the horizon. But this representation is equally faulty, as it gives no idea of a mist covering the surface of the earth. As early as 1820, in Brande's work, the stratus appeared as forming a horizontal BRANDES.-Untersuchungen zur Witterungskunde. Leipzig, 1820, p. 385. |