PHYSICS OF THE GLOBE. 149 



convenient insulating stand, invented by Mascart; and an ad- 

 mirable memoir, by Angot, in the Annuaire of the French Me- 

 teorological Society. 



The fourteenth volume of the " Observations at the Royal 

 Observatory, Edinburgh," contains a supplementary chap- 

 ter on meteorological spectroscopy, in which Piazzi Smyth, 

 in his peculiar style, stoutly maintains that by means of a 

 Browning pocket-spectroscope, he and Mrs. Smyth are able 

 to distinctly perceive the "rain-band" due to absorption by 

 aqueous vapor, and. thereby to predict rainfall with infalli- 

 ble certainty, especially in summer, when the barometer fre- 

 quently fails to be a guide. Although his results are at vari- 

 ance with Hennessy, and possibly Jans sen, yet it is desirable 

 that systematic observations be made on this matter by some 

 of our experienced American spectroscopists. Mr. Abbe has 

 found only a partial success in following Smyth's directions. 



A. S. Herschel has described a convenient method, of attach- 

 ing a measuring-scale to pocket-spectroscopes, such as mete- 

 orologists use in studying the aurora, the aqueous lines, etc. 

 His method consists essentially in substituting for the jaws 

 of a pocket -spectroscope a disk through which is cut or 

 punctured a vertical slit and an oblique row of small holes. 



An excellent review of the investigations and literature 

 relating to the radiometer, by W. H. Stone, will be found in 

 the April number of the Popular Science Review. The idea 

 of using the radiometer as a convenient means of measuring: 

 the solar radiation does not seem likely to lead to any results. 



An important method of determining the temperature of 

 any gas upon which the sun is shining is given by Aymonnet, 

 in the Paris Comptes Hendits, which may evidently be ap- 

 plied to the determination of the temperature of the air by 

 means of thermometers exposed directly to the sun, or other 

 source of heat. Aymonnet's method consists essentially in 

 having two thermometers, or other apparatus, side by side. 

 It is by comparison of their readings, and. after determining 

 a certain constant depending on their instrumental peculiar- 

 ities, that he computes the temperature of the air. 



Intimately connected with the application of Aymonnet's 

 method are the results of an independent investigation by 

 Professor Villain, of Bologna, presented to the Academy, at 

 the same meeting, by Jarain. Villari has investigated the 



