"In order to give a general basis for the equal distribution of members, and prevent the collision of claims too remote for comparative measurement, a proposition is offered for limiting the number of members in the several departments of learning. It is not, however, proposed to render this limitation so minute and special in its character, as to embarrass the action of the Academy, and clog the freedom of selection by an unyielding chain of details, But it is thought, that, if a classified list of all the members is constantly kept, in which they are arranged under the special sciences to which they are devoted, it will prove to be a judicious restraint in the choice of candidates, and an effectual safeguard against their unequal distribution in the different departments.

"The views of the committee are definitely embodied in the following proposed additions to Chapter VII. of the Statutes, the title of which shall be, Of Fellows and Foreign Honorary Members.' It will be observed that no provision is made for limiting the number of Fellows resident in Massachusetts, because it is already provided by the charter that this number shall not be less than forty, nor exceed two hundred.

"2 a. Fellows residing out of the State of Massachusetts shall be known and distinguished as Associate Fellows. Associate Fellows shall not be liable to the payment of any fees or annual dues, and shall not vote at meetings of the Academy, but on removing within the State, shall be admitted to the privileges, and subject to the obligations, of Resident Fellows.'

"2 b. The nomination and election of Associate Fellows shall take place in the manner and under the conditions prescribed in the first article, for Resident Fellows; and moreover, each nomination shall be publicly read and referred to the Council designated in the third article, at a statute meeting previous to that of the election; and a written approval, authorized at a meeting of said Council by a vote of a majority of its members then present, signed by at least seven of said Councillors, and read at the time of the election, shall be requisite to entitle the candidate to be balloted for. The Council may, in like manner, originate nominations of Associate Fellows, which must be read at a statute meeting previous to that of the election, and exposed upon the nomination list during the interval.'

"4. The number of Foreign Honorary Members shall not exceed seventy-five, and they shall be chosen from among those most eminent

in foreign countries for their discoveries and attainments in either of the three great departments of knowledge, viz.: 1st. The Mathematical and Physical Sciences; 2d. The Natural and Physiological Sciences; 3d. The Moral and Political Sciences. And there shall not be more than thirty members in either of these three departments.'

"5. The number of Associate Fellows shall not exceed one hundred, of whom there shall not be more than forty in either of the three departments of knowledge designated in the fourth article.'

"6. It shall be the duty of the Council designated in the third article to nominate, on due consideration, at meetings convened for the purpose, and as vacancies occur, the most suitable candidates for Foreign Honorary Members, to prepare and keep a list of the Fellows, of the Associate Fellows, and of the Foreign Honorary Members, classified according to the general departments of knowledge indicated in the fourth article, and arranged in subdivisions in respect to the special sciences in which they are severally proficient. It shall also be the duty of the Council to exercise a discreet supervision over all the nominations and elections, and to exert their influence to obtain and preserve a due proportion in the number of Fellows and Members in each of the special subdivisions.'"

The committee also recommended the adoption of the following votes:

"Voted, That the Council be, and hereby are, directed to report to the next statute meeting of the Academy a list of all the actual Fellows and Members, arranged in the following divisions, with a statement of the number of each division.

"FIRST CLASS. - MATHEMATICAL AND PHYSICAL SCIENCES.

First Division.

Second Division.

Geology, Mineralogy, and Physics of the Globe.
Botany and Vegetable Physiology.

Zoology and Animal Physiology.

Third Division.

Fourth Division.

Medicine and Surgery.

"THIRD CLASS. - MORAL AND POLITICAL SCIENCES.
Moral and Intellectual Philosophy.

First Division.

Second Division.

Third Division.

Fourth Division.

Philology and Ethnology.

Politics, Political Economy, and Jurisprudence.
Esthetics."

"Voted, That the Secretaries be authorized and directed to cause to be prepared a suitable diploma or form of notification of election for the Foreign Honorary Members."

Dr. B. A. Gould, Jr. presented to the Academy, in behalf of its author, a volume entitled "The Exposition of 1851, or Views of the Industry, Science, and Government of England, by Charles Babbage, Esq.," and called attention to a new and uniform system of lighthouse signals, recommended by Mr. Babbage for universal adoption.

Three hundred and fifty-fifth meeting.

January 6th, 1852, MONTHLY MEETING.

The PRESIDENT in the chair.

Professor Peirce, in behalf of the committee to whom was referred Lieutenant C. H. Davis's paper on the subject of the deterioration of Boston harbor, read the following report:

"The committee to whom was referred the memoir of Lieutenant C. H. Davis upon the state of Boston harbor, have examined the same, and ask leave respectfully to report, that the memoir contains an enumeration of several changes that appear, by a comparison of the charts made at various times, and by other evidence, to have taken place in some of the most important channels of the upper harbor. This part of the memoir embraces a subject entirely local in its character; yet its importance, as affecting the prosperity of a great maritime city, our birthplace and home, may well compensate for the absence of that general interest which belongs to many other subjects of our transactions. The memoir, furthermore, contains an examination of the various causes by which the changes of the harbor have been brought about, influenced, or modified, and by which further changes may be produced. These causes are intimately connected with those general hydraulic forces which are at work wherever tides and streams

are known upon the earth's surface, and have thus a character as general as most subjects of geology or physical geography. The examination of these hydraulic forces, constantly at work in all tidal harbors, has led the author of the memoir to a general specification of the principles which ought always to govern constructions for the improvement of such harbors; and many rules are laid down, the understanding of which must be useful to the hydraulic engineer.

"The committee trust that this short summary of the contents of the memoir will enable the Academy to make a proper disposition of it. They abstain from expressing any opinion upon the accuracy or completeness of the memoir, as they hold to the wisdom of the rule, that the Academy will not, by itself or its committee, become responsible for the accuracy of any facts or opinions expressed by the authors of any memoirs.

"The committee recommend that the memoir of Lieutenant Davis be referred to the Committee on Publications. All of which is respectfully submitted.

"DANIEL TREADWELL,

BENJAMIN PEirce,

JOSEPH LOVERING,

HENRY L. EUSTIS,

MORRILL WYMAN.

"Boston, January 6th, 1852."

Voted, to refer the paper to the Committee on Publications. The discussion of the subject of Mr. Guyot's communication at the last monthly meeting was continued by Professor Peirce, Dr. W. F. Channing, Mr. J. H. Abbot, Professor Lovering, Professor Eustis, Dr. B. A. Gould, Jr., Professor Horsford, and Dr. Jacob Bigelow.

Professor Peirce expressed his dissent from the opinion advanced by Professor Guyot, in respect to the amount of elevating force possessed by any whirlwind, which could be generated by the conflict of opposite winds. He computed the amount of this force in the case of a rotating body of air, extending the full height of the atmosphere, and demonstrated that it was insufficient to account for the phenomena to be explained. He also computed the elevating force possessed

by a column of air extending. to the upper regions of the atmosphere, the temperature of which he supposed to have been raised, according to the principles of Espy's theory, forty degrees Fahrenheit, by the condensation of the aqueous vapor previously contained in it; and he inferred the existence, in this case, of a force capable of elevating bodies of considerable weight.

He stated that he had not been able to test the electrical theories by a similar process of computation, for want of sufficiently definite ideas of their nature. He thought, however, that indications of electrical action in tornadoes were so strong, as to make it very desirable that electricians should investigate the data requisite for such a computation.

Dr. W. F. Channing was satisfied that the causes usually assigned were insufficient to account for the mechanical effects of tornadoes, and was glad that a calculation of the forces of various theories had been undertaken by Professor Peirce. "The rotation in these storms is insufficient to produce a vacuum in the axis of the whirl, adequate to the elevation of heavy bodies by the means of the in-rushing and ascending air. In a water-spout which he had observed on Narraganset Bay, in 1845, the rotation of the trunk was obviously too slow to account for the elevation of the water which took place in the axis. An observer at Somerville had distinctly seen the rotation of the column of the tornado at West Cambridge, a mile and a half or two miles distant. When the smallness of the diameter of this revolving column (a few hundred feet) was considered, the velocity of rotation was at once reduced to a rate insufficient to account for the mechanical effects produced.

"In the beautiful experiment exhibited by Professor Guyot at the last meeting of the Academy, there was a permanent cause of rotation in the upper strata of the revolving fluid; that fluid was inelastic, and it was confined within the walls of a cylinder, which prevented the dispersive effect of the centrifugal force. In the case of the tornado, there is no