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Three hundred and seventeenth meeting.
March 6, 1849. — MONTHLY MEETING.

The PRESIDENT in the chair.

The Vice-President, Mr. Everett, read a letter from Professor Schumacher, of Altona, inclosing printed copies of a communication from the Secretary of the Royal Astronomical Society at London to Lord Palmerston ; also letters from M. Arago and from Baron Humboldt ; touching the position of Professor Schumacher in his connection with the observatory at Altona, and as the publisher of the Astronomische Nachrichten, and the dangers that threaten them in consequence of the disturbed state of the relations between Denmark and the Duchies of Schleswig and Holstein. Whereupon it was unanimously

Resolved, That the American Academy of Arts and Sciences entertains a high opinion of the importance of an observatory at Altona, as a convenient point of communication between countries distant from each other, and of the value of the Astronomische Nachrichten as a medium of intelligence for the whole scientific world ; that it recognizes the great importance of Professor Schumacher's services in connection with the Altona observatory and the publication of the Nachrichten, and would regard as a public misfortune any event which should interrupt his labors, or discourage the generous zeal with which, during a long and honorable career, he has successfully exerted himself for the promotion of astronomical science. .“ Resolved, That a committee be appointed to address a letter to Professor Schumacher, transmitting a certified copy of these proceedings; and that a copy of the letters this evening submitted to the Academy be sent by the committee to the other learned societies and observatories of the United States.”

Mr. Everett, Professor Peirce, and J. Ingersoll Bowditch were appointed to constitute this committee.

Professor Peirce, after calling attention to a recent communication in Silliman's Journal, on the trisection of angles, exhibited an instrument for this purpose, which was devised many years ago, by the late B. R. Nichols, Esq. He also exhibited the model of another instrument, constructed by Mr. Nichols, for the division of an angle into any number of equal parts.

Professor Peirce also presented the computation of the orbit (elliptical) of Petersen's comet, made by young Safford, now thirteen years of age, showing its period to be 382,000 years. He stated that Safford was employed only fifteen hours in the computation.

Professor Peirce likewise made a communication, in which he gave reasons for his belief that all the comets seen by us are component parts of our solar system, drawn from the fact that their orbits are none of them decidedly hyperbolical. He showed that few comets could enter the solar system except in orbits of a manifestly hyperbolic form, derived from the motion of our system in space.

Three hundred and eighteenth meeting.
April 4, 1849. — MONTHLY MEETING.

The PRESIDENT in the chair.

Mr. Everett read a letter from M. Leverrier, in relation to the discovery of the eighth satellite of Saturn. He also exhibited the comet-medal awarded by the king of Denmark to Miss Mitchell, which had just been received, and presented a printod copy of the correspondence which had been held in relation thereto.

Professor Peirce read a letter from Mr. S. C. Walker, containing a comparison of his ephemeris of Neptune with the latest observations on that planet, showing a variation from his calculations of only the fraction of a second. He also adduced further reasons for his opinion that the known comets belong to our solar system, drawn especially from the tendency of their orbits in respect to the plane of the ecliptic. His attention had been drawn to the obvious error of Laplace's argument upon this point by Dr. B. A. Gould, Jr. ; who has made a chart of the path of the orbits of the comets, which is conclusive in its exhibition of the relation of the comets to the solar system.

Dr. J. C. Warren and Dr. Channing continued a discussion which commenced at the last meeting, on the comparative merits and safety of ether and chloroform as anæsthetic agents.

Three hundred and nineteenth meeting.
May 8, 1849. — Monthly Meeting.

The President in the chair.

The Corresponding Secretary presented a memoir from William S. Sullivant, Esq., entitled “Contributions to the Bryology and Hepaticology of the United States, Part II.," comprising the descriptions of several new or little known Musci and Hepaticæ, illustrated by figures.

Professor Agassiz gave a summary account of his investigations upon Medusæ. He has ascertained that their body consists entirely of cells, preserving in all the different systems of organs their character as true cells, and nevertheless performing very different functions. He showed that there is a complete system of bundles of elongated cells, arranged in longitudinal and transverse series, acting as muscles, and disposed in several layers, one being superficial and another lining the inner surface of the disk in Discophoræ, whilst some penetrate at various depths the gelatinous mass. The nervous system consists of a circular cord of oval cells, extending along the lower margin of the disk, from one eye-speck to the other, and forming a ganglion at the base of each. He also showed that the digestive system is naturally distinct from the tubes through which the digested food, mixed with water, is circulated, though at times they communicate directly with each other. This circulation — the arrangement of which he has ascertained by artificial injection is very complicated in

Ctenophoræ, as there are peculiar tubes for each row of combs, for the netting apparatus, for the stomach, for the mouth, and for the ocular bulb. He further showed that the walls of the digestive and circulating cavities are cellular, like the other parts of the body, and that the gelatinous mass itself is divided into large cells by partitions similar to the hyaline membrane of the vitreous body of the eye. He also illustrated the various modes of development of these animals, and described the successive changes of their alternative generations in the Tiaropsis diademata ; the embryo of which he has seen escape from the ovary, move about free for some time, and finally attach itself and grow into a polyp-like animal with tentacles, the first stage of growth of a Campanularia, which is its other mode of existence. He finally enumerated the species of Ctenophoræ and naked-eyed Discophoræ which he has observed in Boston Bay, referring them to the modern genera to which they belong, viz. Pleurobrachia rhododactyla, Bolina alita, Staurophora laciniosa, Bougainvillea superciliaris, Sarsia mirabilis, and Tiaropsis diademata, pointing out the differences by which they are distinguished from the species already described, and the generic characteristics of the new type he has recognized among them. The discovery of a new species of Staurophora on these shores is a new instance of the remarkable analogy which exists between the fauna of the Atlantic States and that of the northeastern shores of Asia.

Dr. B. A. Gould made some remarks on the comet now visible, which had passed remarkably near the earth during the last week. He had, however, in spite of this near approach, heard of but two observers who had seen it with the naked eye, namely, Mr. Bond, in Cambridge, and a gentleman in Salem.

“ The first rough elements deduced from observation, within two days after its discovery, were so strikingly similar to those deduced by Bessel (Berliner Astronomisches Jahrbuch, 1809, p. 99) from Klinkenberg's observations of the second comet of 1748, as to lead to strong suspicion of the identity of those two bodies. The following are the third parabolic elements computed for this comet, (originally published by S. C. Walker, Esq., in the National Intelligencer of April 26th,) from Cambridge observations, April 11th, 14th, and 19th, and Bessel's elements for the comet of 1748. 1848. Mean Berlin Time. 1748. Mean Paris Time. T June 84.23220

T 184..89401 8 30° 32' 7"

8 33° 8' 29" ¿ 66 55 12

i 67 3 28 7 267 13 6

a 278 47 10 9 0.892703

90.625357 Motion direct.

Motion direct. “ The discrepancies between these two orbits are not greater than the uncertainties of the latter, except as regards the perihelion distance. Both comets were very favorably situated for determination of the perihelion distance, and on mature consideration I am convinced, that, unless it can be shown that the comet had been exposed to perturbations, by the earth or Jupiter, capable of producing a very great change in the perihelion distance, all arguments, drawn from the similarity of the elements, in favor of the identity of the two comets, must fall to the ground. In both cases, the comets approached quite near the earth, and were observed in the ecliptic; but in 1748 the comet crossed this plane so far inside the earth’s orbit, and in 1849 so far outside of the same, that all attempts to attribute the discrepancy of the perihelion distances to errors of observation or computation, in either case, must be fruitless.

" It must, nevertheless, be acknowledged that the resemblance of the two orbits is greater than exists between those of any other two comets on record. In order, therefore, to discover whether any indication of periodicity were to be found in the orbit itself, application was made to Mr. Bond, of the Cambridge Observatory, for three observations, as remote from one another as possible ; and from observations on April 11th, 19th, and 27th, I computed an orbit by Gauss's method, without any hypothesis whatever as to the nature of the conic section described. The resulting curve was no ellipse at all, but the following hyperbola.

8 30° 11' 11"
¿ 67 19 39
a 266 16 36
4 10 6 1

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