Page:Popular Science Monthly Volume 5.djvu/520

504 Butts & Co., 1874. 2 vols., 8vo, 1820 pp. Price, $27.00.

Descriptions of New North American Phalænidæ and Phyllopoda. By A. S. Packard, Jr. Salem, Mass., 1874. 18 pp.

Essays and Addresses by Professors and Lecturers of the Owens College, Manchester. London: Macmillan & Co., 1874. 8vo, 560 pp. Price, $5.00.



The Priestley Celebration at Northumberland.—The proposition for a Chemical Centennial, alluded to in the June number of the has taken practical shape, and is to be carried out by a meeting or celebration at Northumberland, Pa., beginning on the 31st of July, 1874. A large number of the eminent chemists of the country have united in an invitation to their brethren to participate in the exercises of the occasion, in the belief that it will foster a feeling of fraternity, and afford a fitting opportunity for that interchange of ideas so important to the advancement of science. Prof. H. Carrington Bolton, of the Columbia College School of Mines, is chairman of the general committee having the matter in charge, and any information respecting the arrangements for the meeting may be obtained by addressing him. In a circular issued by this committee, those planning to attend the meeting at Northumberland are requested to send their names to Dr. Robert McCay, of that place, secretary of the local committee of which Dr. Joseph Priestley is chairman.

In order to add to the interest of the occasion, a Loan-Exhibition will take place during the meeting, for displaying apparatus, books, manuscripts, etc., etc., belonging to Dr. Priestley, or other objects illustrating the history of chemistry. Gentlemen interested are earnestly requested to contribute any thing in their possession appropriate to this exhibition. It is expected that the exercises will include an address by Prof. Joseph Henry; a sketch of the life and labors of Priestley, by Prof. Henry H. Croft; a review of the century's progress in theoretical chemistry, by Prof. T. Sterry Hunt; a review of the century's progress in industrial chemistry, by Prof. J. Lawrence Smith; and an essay on American contributions to chemistry, by Prof. Benjamin Silliman. Detailed programmes of the exercises will be distributed at the meeting.

Belt's Theory of Cyclones.—In the "Naturalist in Nicaragua," Mr. Belt has the following on the origin of whirlwinds and cyclones: "I am confident that a study of the smaller eddies of air is the proper way to approach the difficult question of the origin of cyclones." The movements of these small whirling masses may be observed from the outside, and their progress traced from the incipient stage to that of dissolution. In the beginning of a whirlwind there is a movement near the surface of the ground of light particles of dust toward a centre, attended or occasioned by a rotary motion of the air. This quickly rises into a whirling column from fifty to a hundred feet or more in height. On the dry hot plains of Central and South America, and of Australia, this phenomenon is of frequent occurrence, and is not unusual in our temperate latitudes in summer. The whirling columns, according to Mr. Belt, differ in diameter from a few feet to many miles, and his opinion is that "there is a complete gradation from the little dust-eddies, through larger whirlwinds and tornadoes, to the awful typhoons and cyclones of China and the West Indies."

In the small whirlwinds which occur over the land, there is no evidence of the condensation of vapor occurring in dry air. But, where the atmosphere is charged with humidity, as over tropical seas, the condensation is great. The notion, therefore, that whirlwinds and tornadoes originate in sudden condensation, Mr. Belt thinks not well founded, the phenomenon being an incident rather than a cause of the movement. Nor is the theory a satisfactory one, that the meeting of conflicting currents of air and consequent condensation give rise to the phenomenon. Attention is directed to the fact that many terrible whirlwinds are dry, and ran their course without producing rain or cloud. They originate at or very near the surface of the ground, where the air 