Junk 16, 1899. ] 



SCIENCE. 



849 



finally, that even such bacteria as may have 

 been accidentally present on the leaves are 

 killed in the curing process. He has discovered 

 two oxydizing enzymes the proportions of 

 which are determining factors in the produc- 

 tion of the color and aroma of tobacco. Faulty 

 methods of curing may destroy these enzymes 

 and prevent the changes which bring about 

 improved flavor. The nicotine, which does not 

 exist in the fresh leaf, is one of the products 

 formed during the action of the enzymes. 



Professor Whitney offered the opinion that 

 Dr. Loew's discoveries were to be looked upon 

 as the beginning of a scientific understanding of 

 the processes of acquiring color and aroma, and 

 that they marked a new departure of great 

 scientific and practical importance. Dr. Loew 

 then replied to various questions by Dr. de 

 Schweinitz and others. 



O. F. Cook, 

 Secretary. 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON. 



The 503d meeting of the Society was held in 

 the assembly room of the Cosmos Club at 8 p. 

 m., May 27th. The first paper was by Mr. 

 Frank Radelfinger on ' Some Recent Researches 

 on Linear Differential Equations.' 



After a brief introduction reviewing and sum- 

 marizing the methods used in the solution of 

 differential equations before the introduction of 

 the complex variable into analysis the work of 

 Fuchs on the theory of linear differential equa- 

 tions was considered and its salient points 

 denoted. The researches of Thome and Poin- 

 care on equations with irregular integrals were 

 very briefly treated, and then came the princi- 

 pal part of the paper, giving an account of the 

 recent introduction of the ideas of the Galois- 

 group theory into the theory of the linear differ- 

 ential equation. The work of Picard and Ves- 

 siot was discussed. A statement of the princi- 

 pal theorems of the linear group was given and 

 their analogy to those relating to the symctrical 

 group of algebra mentioned. A concise state- 

 ment of the theory of irreducibility and its ap- 

 plication to the theory of linear differential 

 equations was made, and it was shown that 

 the results obtained by the group theory when 

 combined with this idea furnished us with a 



rational basis for their classification. This was 

 illustrated by making an application to the case 

 of an equation of the second order. The con- 

 ditions that must be satisfied by a linear equa- 

 tion in order that it may be integrated by quad- 

 ratures was next discussed. In conclusion, some 

 points to be perfected in the theory of equations 

 with irregular integrals were indicated and 

 mention made of recent researches in the 

 theory of divergent series that may throw some 

 light on these points ; the importance of the 

 group theory was mildly emphasized and a 

 statement made of the results to be expected 

 from its further application to the theory of 

 linear differential equations, especially in re- 

 gard to arithmetization of this theory. 



The second paper was by Mr. Louis D. Bliss 

 on ' Hertzian Waves as applied to Wireless 

 Telegraphy and Firing of Guns from a Distance.' 

 The substance of Mr. Bliss's remarks was as 

 follows : Upon the electro-magnetic theory of 

 light proposed by Maxwell in 1867 Hertz in 

 1888 succeeded in producing signals through 

 space, without the aid of any material medium, 

 by the propagation of electro-magnetic waves. 

 For a transmitter he employed an ' Oscillator ' 

 and for a receiver a ' Resonator ' of special 

 design. 



Marconi, in 1895, reduced to practical form 

 what was thus far experimental, by the con- 

 struction of a 'Coherer' or 'Electric Eye,' 

 consisting of a glass tube filled with metal 

 powder on which the waves could strike. The 

 resistance of the powder was thereby greatly 

 diminished on account of the cohesion of the 

 particles under the influence of the waves. 

 This permitted a battery (which was constantly 

 in circuit) to force a powerful current through 

 the device, and thus operate a telegraph relay 

 or sounder, or operate a fuse to fire a cannon, 

 mine or other device at will. These signals 

 may now be transmitted through space between 

 stations 30 miles apart, the height of the verti- 

 cal wire which must be connected to the ap- 

 paratus at each station varying as the square 

 root of the distance. (Demonstrations of firing 

 a cannon without wires and telegraphy through 

 space were made.) 



E. D. Preston, 



Secretary. 



