being uniform, while the velocity in lead diminishes very rapidly.

24. The siphon action with a tin bar cannot be long maintained, on account of the crystallization and consequent brittleness of the bar.

25. The crystalline amalgam has a constitution of Hg Sn。. 26. The liquid amalgam contained 1.55 per cent. to 1.73 per cent. of tin.

27. The crystalline amalgam loses nothing by atmospheric diffusion.

28. Quicksilver permeates gold and silver, but very slowly. 29. Zinc and cadmium are permeable to mercury, but dissolve in it.

30. Iron, platinum, palladium, and copper bars are not at common temperatures permeable to mercury.

Three hundred and fifty-sixth meeting.

January 28, 1852.-ADJOURNED STATUTE MEETING. PROFESSOR PEIRCE in the chair.

The Recording Secretary reported a list of the Members of the Academy, arranged in classes and sections by the Council, agreeably to the vote of the Academy at its last statute meeting.

The Academy then proceeded to consider the amendments to the statutes reported by Professor Peirce at the last statute meeting. After some discussion, it was

Voted, That the amendments to the statutes, proposed at the adjourned statute meeting held December 3, 1851, be adopted.

Dr. B. A. Gould, Jr. stated several reasons, which he thought rendered it desirable that the nomination of Foreign and Associate Members should be vested, as far as practicable, in those sections of the Academy, to which, if elected, they would belong. After a long discussion, he offered the following amendment to the statutes:

"The Council for nomination shall consist of the President, VicePresident, and the two Secretaries, together with three Fellows from each of the three classes of the Academy, to be elected by ballot at the annual meeting and it shall be the duty of the Council, in nominating Foreign and Associate Members, to consult the wishes of that section of the Academy to which, if elected, the candidate would belong."

On motion of Mr. Gould, it was

Voted, That this proposed amendment be referred to a special committee, with instructions to report it, with such modifications as they may deem expedient, for the action of the Academy at their annual meeting in May.

Voted, That Professor A. Gray, Professor Horsford, Dr. B. A. Gould, Jr., Dr. W. F. Channing, and Mr. J. D. Whitney be that committee.

Three hundred and fifty-seventh meeting.

February 3, 1852.- MONTHLY MEETING.

The PRESIDENT in the chair.

Professor Peirce made an oral communication of considerable length, on the "Surface of Least Extent."

Professor Eustis exhibited to the Academy a very elaborate and beautifully executed plan, on a large scale, of three miles and a quarter of the track of the late tornado in Middlesex County, beginning at Wellington Hill in Waltham, and extending north 70° east to Mystic River. He commenced the survey ten days after the occurrence of the tornado, and completed it in eleven days, with the help of twenty assistants. In describing his method of conducting the survey, he stated that he first determined a central line, and then divided the track into sections, by transverse lines at intervals of one hundred feet. He measured the exact position and direction of every important object with reference to these lines. He pointed out some of the more striking features of the tornado as indicated by his plan.

On motion of Professor Peirce, it was

Voted, That Professor Eustis's plan be referred to a special committee.

Voted, That Hon. R. C. Winthrop, Professor Peirce, J. I. Bowditch, Esq., Mr. G. B. Emerson, and Professor Lovering be that committee.

Dr. C. T. Jackson exhibited a specimen of cannel coal from the Peyton coal mine, situated on a tributary of the Kenhawa, in Virginia. He stated that the coal-bed is horizontal, and from six to eight feet in thickness; and called attention to the electrical attraction which is developed in the coal by friction, a property which he had observed in a few instances in coal taken from other mines.

Dr. W. F. Channing remarked, "that the arrangement of the Municipal Fire Telegraph, now approaching its completion in Boston, presents a very close analogy with the nervous system of the individual. This was the result of no theory, but a practical necessity, in order to unite the various parts of the Municipal system by an intelligent and coöperative law.

"Thus in the Fire Telegraph there is a centre which is the brain, the common reservoir of nervous or electric force for the whole system, presided over by an intelligent will (the watchman of the central station). From this centre radiate two classes of electric conductors or nerves. The first of these, the Signal Circuit,' conveys impressions to the centre, and is afferent,'' sensitive.' The second of these, the 'Alarm Circuit,' conveys impressions from the centre, and is 'efferent,' 'motor.' When any disturbance occurs at the circumference of the system, it is signalized from the 'Signal Boxes,' which are the 'sensitive extremities' of the sensitive conductors to the centre; from which, after an act of intelligence and volition, an impulse to appropriate or corresponding action is instantly sent over the motor nerves or conductors to the various belfries, where the electric or nervous agent animates the iron limbs, by means of the contraction of electro-magnetic muscles, thereby releasing powerful machinery to strike a single blow upon each of the bells. By a combination of such blows,

by the act of the intelligent will at the centre, district signals, or any others, may of course be struck.

"The perfection of this analogy is a guarantee, in addition to the various ends of security and intelligent action which are thus obtained, that the arrangement is in conformity with a natural law."

Professor Eustis called attention to an optical illusion which takes place when an isometric drawing is seen in a vertical position from a certain point of view, but which fails when the drawing is horizontal or much inclined, namely, the apparent convergence of the parallel lines.

Dr. C. T. Jackson stated "that he had lately had an opportunity of examining the specifications and drawings accompanying the patent for an apparatus, invented by Dr. Gorry, for making ice by compression of air, abstraction of the heat by a jet of cold water, and by a sudden expansion of this condensed air by means of an air-pump worked by steam; the heat being suddenly absorbed by the expanding air. This method has been employed for the production of large blocks of ice, one of which, in a single piece, is said to have weighed 600 pounds. It is stated by Professor Renwick, that the cost of making three tons of ice will not be more than ten dollars.

"It is now proposed to employ this machine for the freezing of water for the production of fresh from sea-water; the fresh water only freezes, and the brine is to be drawn off. Three successive freezings will make sea-water fresh and drinkable. Dr. Jackson thinks this method worthy of trial on board the ocean steamers, which have an abundance of steampower always ready. The machine is described as not cumbersome, and capable of being worked easily on board ship.

"The principal difficulty is in preventing the effects of expansion of freezing water in the apparatus, which is liable to be burst thereby."

J. I. Bowditch, Esq., in the absence of the chairman of the committee appointed to confer with the Trustees of the Boston Athenæum, on the subject of obtaining a room for the use of the Academy in the Athenæum, made a report. After much discussion, it was voted,

1. That the report of the committee be accepted.

2. That the contract entered into by the committee, in behalf of the Academy, for the use of the northeast room on the lower floor of the Athenæum, for the period of ten years, on the terms specified in the committee's report, be ratified.

3. That the same committee be empowered to complete the arrangement with the Trustees of the Athenæum.

4. That the same committee be empowered to effect the removal of the books belonging to the Academy, and to dispose of the bookcases in such manner as they may see fit.

Three hundred and fifty-ninth meeting.

March 2, 1852.-MONTHLY MEETING.

The PRESIDENT in the chair.

Mr. Winthrop, in behalf of the committee on the subject of Professor Eustis's plan of the late tornado, submitted the following report:

"The committee of the Academy, to whom was referred a plan exhibiting the ravages of the tornado of August, 1851, by Professor H. L. Eustis, beg leave to report,

"That they have examined this map with great interest, and are unanimously of the opinion, that it forms a very valuable contribution to the cause of meteorological science.

"In meteorology, as in every other science, much more depends on the fidelity and accuracy of observations and experiments, than on the multiplicity of them. A single tornado, carefully and thoroughly surveyed, is worth a hundred of which the track has only been galloped over by the observer.