504 



THE POPULAR SCIENCE MONTHLY. 



Butts & Co., ISU. 2 vols., 8vo, 1820 pp. 

 Price, $2'7.00. 



Descriptions of New North American 

 Phalaenidae and Phyllopoda. By A. S. Pack- 

 ard, Jr. Salem, Mass., 1874. 18 pp. 



Essays and Addresses by Professors 

 and Lecturers of the Owens College, Man- 

 chester. London : Macmillan & Co., 1874. 

 8vo, 560 pp. Price, $5.00. 



MISCELLANY. 



The Priestley Celebration at Xorthnm- 

 berland. — The proposition for a Chemical 

 Centennial, alluded to in the June number 

 of the Monthly, has taken practical shape, 

 and is to be carried out by a meeting or 

 celebration at Northumberland, Pa., begin- 

 Ding 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 exer- 

 cises 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. Carriugton 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 meet- 

 ing 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 appara- 

 tus, books, manuscripts, etc., etc., belong- 

 ing to Dr. Priestley, or other objects illus- 

 trating the history of chemistry. Gentle- 

 men interested are earnestly requested to 

 contribute any thing in their possession 

 appropriate to this exhibition. It is ex- 

 pected 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 Amer- 

 ican 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 " Nat- 

 uralist in Nicaragua," Mr. Belt has the fol- 

 lowing 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 ob- 

 served from the outside, and their progress 

 traced from the incipient stage to that of 

 dissolution. In the beginning of a whirl- 

 wind 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 Amer- 

 ica, 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 tor- 

 nadoes, 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 con- 

 densation of vapor occurring in dry air. 

 But, where the atmosphere is charged with 

 humidity, as over tropical seas, the conden- 

 sation is great. The notion, therefore, that 

 whirlwinds and tornadoes originate in sud- 

 den 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 run their course without producing* rain 

 or cloud. They originate at or very near 

 the surface of the ground, where the air 



