ated, molluscous, articulated, or vertebrated, and that the distinctive characters of these sub-kingdoms are consequently those first evolved; —that, in the further progress of development, the characters of the classes next present themselves, then those of the orders, then those of the families, genera, and species consecutively, and lastly those of the individual. We are quite sure,' continues the writer, that Professor Milne Edwards could not have been aware that he had been completely anticipated in this doctrine by Dr. Martin Barry; or, with his accustomed candor, he would have alluded to the circumstances.'

"Dr. Barry's views, contained in two papers in Professor Jameson's Edinburgh New Philosophical Journal for January and April, 1837, are most clearly expressed. In the first of these pa pers, he works out the important principle of Von Baer,-that a heterogeneous or special structure can arise only out of one more homoge neous or general, and this by a gradual change;' and applies this to the different directions of development, which present themselves in the primary subdivisions of the animal kingdom at a very early period of the history of the embryo, pointing out at the same time (as M. Milne Edwards has subsequently done) that this fact completely negatives the idea that the vertebrated animal ever passes through the conditions which are characteristic of the radiated, the molluscous, or the articulated. He further shews that the order in which the distinctive characters of the germ are evolved, is that of their generality in the animal kingdom. Thus, in development, the structure characteristic of the vertebrata only cannot manifest itself until there has been assumed essentially a structure common to animals, of which the vertebrata are but a part, and to whose type the type of the vertebrata is subordinate. In like manner, structures subordinate to the type of the vertebrata cannot manifest themselves, until after a modified appearance of the general type, of which they are but partial metamorphoses. More and more special forms are thus reached in succession, until the one most special is at length attained.' In his second paper, he expresses this view still more clearly, in the following table of the history of develop. ment of any single organism :

1. No appreciable difference in the germs of all animals (fundamental unity.)

2. The class manifest, but the order not distinguishable.

3. The order manifest, but not the family.

4. The family manifest, but the genus not known.

5. The genus obvious, but not the species.

6. The species manifest, but the variety unpronounced.

7. The variety obvious, but the sexual difference scarcely apparent. 8. The sexual character obvious, but the individual character obscure. 9. The individual character in its most special form.

"In both papers, Dr. Barry continually puts forth this principle as the groundwork of classification. Thus he says: The only sure basis for classification is not structure, as met with in the perfect state, when function tends to embarrass, but-the history of the development, at that period when structure presents itself alone.' And again: 'the fact is, that naturalists have begun just where they should have ended.

They have attended to details, but neglected general principles. Instead of analyzing, their process has been one of synthesis. Their attention has been directed to the grouping of the twigs,-as if they were thus to find their natural connexions, without even looking for assistance towards the branches, or the trunk that gave them forth. But the simile is inadequate; the labor lost has been greater than even this supposes. For in the grown tree of animal structure, parts, once essentially the same, have not only diverged in their development, and become elaborated into very different forms,-but, as before said, perform very different functions also. Hence a positive in addition to a negative source of error. But what other course could naturalists have taken? Truly none: their circumstance' allowed no other. It is only now that a way is beginning to be opened, by which it may, by and by, be possible to proceed in an opposite direction, viz., from trunk to branches and twigs. This, if ever accomplished, must be by means of the History of Development or Embryology.'

"We have thought it right to bring forward Dr. Barry's claim as the first distinct enunciator of this doctrine, because we perceive that its truth is being more and more generally recognized, and that it must ultimately become the foundation of all philosophical zoology."

IV. ASTRONOMY.

1. Observations during the Lunar Eclipse, September 12, 1848; by LEWIS M. RUTHERFORD, (in a letter to the Editors, dated New York, Sept. 28, 1848.)-In the course of some observations made during the occurrence of the lunar eclipse, on the night of the 12th inst., I was struck with the arrangement of the colors visible in the earth's shadow. In the penumbra, I could not detect the prevalence of any particular one of the prismatic hues, but it appeared as a mere diminution of the moon's brilliancy, without any apparent change of color, except a grey shade as it deepened immediately preceding the true shadow. The shadow of the earth had a diameter not far from three times that of the moon; and if it had been projected upon a plane surface of uniform color, sufficiently large to present the whole at one view, it would have appeared with a circle in the centre, rather less than the moon, of a deep red copper color; the reddish tinge of this central disk was plainly visible to the unassisted vision, became much plainer in a telescope of three inches aperture, and with one of six inches, the red almost predominated over the brown in the copper hue. This disk was surrounded by a belt of yellowish orange, leaving a margin of greyish green occupying rather less of the diameter of the shadow than the annulus of yellowish tinge: these three divisions, although shading gradually into each other, were almost as well defined in their limits as was the exterior of the shadow itself, and although not at all comparable to the solar spectrum as shown by an ordinary prism, in clearness and brilliancy of color, were yet too apparent to have been overlooked by the most casual observer, the first two being easily seen by the naked eye, and the last detected by the slightest optical assistance, and all evincing a remarkable increase of depth and individuality as a larger aperture was applied.

The translucent atmosphere which surrounds the earth, in this case acting as a spherical lens, refracted the sun's rays to a focus at some point between us and the moon, and in this process dispersed them into their primary colors; and these having crossed at the focal point, we find, as might have been expected, the red or least refrangible ray cov. ering the centre of the disk, surrounded in the proper order of refrangibility by the orange, yellow and green; but in no part either of the umbra or penumbra, could I detect any traces of the remaining colors of the spectrum, the blue, indigo, or violet. It was the absence of these tints which struck me as remarkable, and as being a subject upon which I had never met with any remarks either of notice or explana tion; in the few printed accounts of lunar eclipses which I have seen, not one of the observers has mentioned the occurrence of any of the blue tints, while all have noticed the green, orange and copper red, although without speaking of their order as portions of the spectrum, or noticing the absence of the remaining three. The appearances above detailed, brought to my recollection a circumstance before observed but never heeded. It is this, that in looking at one of the planets or a bright star within a few degrees of the horizon, with a reflector or well corrected achromatic, the object is tinged with prismatic colors, the red, orange, yellow and green being very bright, while the others are absent as in the case of the lunar eclipse. I am unable to suggest any mode of accounting for these phenomena, which is exempt from strong objections; the most obvious are the following. The violet, indigo and blue rays being much the most refrangible, may be lost by being thrown so far from the umbra of the earth, as to be unseen in the brilliancy of that part of the moon which receives the full splendor of the sun; this would be the case with the extreme violet ray, which would precede the green by a distance nearly equal to the interval be. tween it and the red, and consequently would be well without the circle of the penumbra; this would not be the case however, with the indigo, and still less with the blue, which last would (if it occupied its proper proportionate space in the concentric prismatic annuli) adjoin the green in that part of the penumbra which is so dark, as readily to betray the preponderance of any color, it being in truth difficult to mark the line which separates the shadow from the penumbra. The only other hypothesis which occurs to me is, that the earth's atmosphere, although to us transparent, has in reality an intrinsic color, such as would be form. ed by the combination of red, orange, yellow and green; in conse quence of which these colors are transmitted, while the others are ab. sorbed the same cause may operate to impart to the heavenly bodies, when near the horizon, the ruddy hue they always wear when setting or rising; and it will be remembered, that a ray passing from the sun along the surface of the earth, and reaching by refraction the umbra on the moon, passes through an extent of atmosphere double that traversed by any ray which reaches us from the rising sun, and would consequently render much more visible the effect of chromatic absorp tion, if it existed. The objection to this theory, is the blue vault above us often deepening into an indigo, and always too palpable to be explained away by any theory of complementary colors. The night of the 12th was beautifully clear and quite cold, and as the silver surface

of the moon was veiled, the milky way and the smaller stars gradually shone out, the nebula in Andromeda and the cluster in Hercules became visible to the naked eye. Saturn was within a few degrees of the moon at the time; before the commencement of the eclipse, with my largest telescope the ring could with difficulty be discerned, with but two satellites. During the period of the moon's greatest obscuration, the planet seemed pierced by a bright silver wire of infinite tenuity, attended by five satellites, one of which was impaled upon the following ansa of the ring, but moved off with very appreciable speed. I will not trouble you with the time at which the various points of the eclipse occurred, as they are at best but rough and useless subjects of observation. I would however trespass a little further upon your indulgence, while I say something of the instrument with which these observations were made. My largest is an achromatic telescope, equatorially mounted, of six inches aperture and eight feet focus. The ob ject-glass is the workmanship of Mr. Henry Fitz of this city, an optician of great skill and rising reputation; the flint glass, which is quite pure, he obtained from Guinand's establishment in Paris. I believe this object-glass to be free from aberrations, both spherical and chromatic, saving the secondary spectrum which is present in all achromatics in proportion to their apertures; its light is sufficient to shew plainly under favorable circumstances, the stars called by Capt. Smythe, in the Bedford catalogue, the 16th magnitude, and which he says are only caught by occasional glimpses under the most favorable circumstances by his instrument. It renders the companion of a Lyræ, and the fifth star in the trapezium of Orion, visible under sufficient illumination for micrometric measurement; its defining power enables me to see the rugged cliffs and volcanic chasms of the moon most beautifully; it has shewn me at one time last winter, the disk of Jupiter covered with small belts, in addition to the two usually seen, while two of his satel lites were plainly seen projected upon the planet's disk, followed by their shadows, which were as distinct as black wafers upon white paper, the difference in their magnitude being easily seen without measurement; it very much elongates 7 Coronæ, and enables me readily to measure the position and distance of the close pair of the triplet of Cancri with a power of 200, which is the highest my micrometer is provided with. I take great pleasure in bringing to your notice, the workmanship of Mr. Fitz, as he is an American and a self-taught artist, who places within our reach at home, those instruments which heretofore have been obtained from abroad, at a great cost.

η

2. Eighth Satellite of Saturn.-An eighth satellite of the planet Saturn has recently been discovered by Mr. Bond, of the Cambridge Observatory. Its orbit is exterior to that of Titan, which (in Sir J. Herschel's new nomenclature of these satellites) is the bright satellite discovered by Huyghens, and hitherto supposed to be the most remote but one from the planet.

3. New Comet.-Dr. Petersen, of Altona, discovered a new telescopic comet on the 7th of August, 1848.

4. Elements of the orbit of the Planet Hebe, (Comptes Rendus Acad. Sci., July 10, 1848.)-M. Yvon Villarceau, from a discussion of all the observations he could procure, has deduced the following elements of Hebe.

Mean anomaly, July 0, 1847, m. t. Paris, 272° 29′ 25′′0

5. Elements of the Planet Metis, (Institut, July 12, 1848.)-Mr. Graham, of Markree, Ireland, has furnished the following elements of the planet Metis, discovered by him, April 25, 1848. It is his second approximation, and is based on the observations made at Markree, April 26, May 5 and 19.

Epoch, 1848, May 0-0, m. t. Greenwich.

Mean anomaly,

Longitude of perihelion,

Inclination,

"ascending node,

Angle of excentricity,

Log. of semi axis major,

Mean daily motion,

Period of sidereal revolution,

6. Speculations on the next Planet beyond Neptune; by M. BABINET, (Institut, Aug. 23, 1848.)—The fact that the planet Neptune differs so essentially in its orbit and mass from the theoretical planet of Le Verrier and Adams, induced M. Babinet to undertake an investigation, having for its object to ascertain if the perturbations in the motions of Uranus could be made to indicate a second exterior planetary body, which with Neptune should explain all the anomalies.

Assuming that the effects of the theoretical planet of Le Verrier are the resultant of the combined action of Neptune and another planet more distant, M. Babinet proposes this problem. "Admitting as exact the mass, distance, period, position Jan. 1, 1847, of the theoretical planet of Le Verrier, by what union of two other planets, of which Neptune shall be one, can this theoretical planet be replaced, in order to obtain the same resultant effect; and consequently what must be the mass, the distance, the longitude, and the apparent size of a new planet which combined with Neptune, will represent the theoretical planet of Le Verrier?"

M. Babinet gives the following results of his investigations, as probable within certain limits.

1. The planet complementary to Neptune is in mass, size, and brilliancy, at an equal distance, little different from Uranus. Hyperion is proposed as its name.

2. Its distance from the sun is forty-seven or forty-eight times that of the earth's distance.

3. Its period of revolution is double that of Neptune, as that of Neptune is double that of Uranus.