METKOROLOGY. 401 



new meter for measuring electric currents. He says : •' The force due to 

 an electric current is proportional to the square of the current; hence if 

 part of an electric circuit is capable of vibrating under an electro-mag- 

 netic force, the speed of vibrations will be proportional to the strength 

 of the current. If, then, such a contrivance takes the place of a balance 

 of a pendulum clock, the latter will measure electric currents instead of 

 time." {Nature, xxv, p. 355.) 



Mascart describes to the Paris Academy of Sciences his method of 

 determining the quantity of carbonic acid contained in the atmosphere. 

 He measures directly the diminution of i)ressnre of a mass of air conse- 

 quent on the removal of the carbonic acid. Travelers will find it more 

 convenient to fill glass flasks with the air of their localities, and submit 

 the contents to analysis on their return home. {Nature, xxvi, p. 119.) 



The application of mechanical methods to replace laborious mathe- 

 matical computations is sometimes so ingenious that there is every 

 reason to hope that mechanical methods may yet be devised for taking 

 into account the numerous disturbing elements that affect the motions of 

 the atmosphere, thus enabling us to quickly predict from the weather- 

 maps of to-day what the weather-map of to-morrow will be, instead of 

 going through the laborious use of tables and estimates that always 

 have the appearance of empiricisms. We are led to these remarks by 

 reading the resum^ of a pajier on integrating machines presented by 

 Mr. C. V. Boys to the London Physical Society. {Nature, xxv, p. 161.) 



G. H. Darwin, in connection with his tidal investigations, has drawn 

 some conclusions with reference to Jupiter's atmosphere, which latter he 

 believes to be the cause of the well-known belts. He finds that the rapid 

 rotation of the nucleus is not sufficient to explain the belt ; but that 

 with it we must assume a proportionately large amount of gas in its at- 

 mosphere and a high temperature for the nucleus. {Nature, xxv, p. 300.) 



Prof. J. J. Thomson has communicated to the Koyal Society of Lon- 

 don a memoir on the vibration of a vortex ring and the action of two 

 vortex rings upon each other. This was an important paper on hydro- 

 dynamics, bearing as it does directly upon the question of the repre- 

 sentation of optical phenomena by the vortex -ring theory of the con- 

 stitution of matter. {Nature, XXV, j). 354.) 



Chardonnet communicates his experimental study of actinic power 

 and the influence of specular polish. This polish increases the total 

 quantity of radiations reflected, but the relative intensities of different 

 portions of a spectrum depend on the material of the mirror. {Nature, 

 XXVI, p. 520.) 



Yiolle describes a calorimeter depending on cooling, and adapted 

 especially to very high temperatures. It consists of a small, narrow- 

 necked bottle of thin glass, with double envelope, and a vacuum pro- 

 duced in the interval before the closure. Through the neck are intro- 

 duced a thermometer and a stirrer. {Nature, xxvi, p. 168.) 



Deprez described, at the La Rochelle meeting of the French Associa- 

 H. Mis. 26 26 



