428 Notices respecting New Boohs. 



<end of the wire. The disturbance in the immediate neigh- 

 bourhood of the free end that gives rise to this radiation 

 appears to be of the same kind as in the electrical discharge 

 from a conductor which has a sharp point on it. It would 

 follow from this that the mechanism by which energy is 

 radiated from the extremity of a Marconi antenna is the 

 same as that by which the electric charge of a conductor is 

 discharged from a sharp point on it, and that it receives 

 energy in the same way as a lightning-conductor discharges 

 a thundercloud. These considerations appeared to me to lead 

 to the conclusion that the radiation from the free end was the 

 important factor both in the case of the Hertz resonator and 

 of the electrical oscillations associated with a terminated wire. 

 The mathematical representation of this radiation when the 

 oscillations are not maintained steady presents difficulties 

 which so far have not been overcome ; but when the oscil- 

 lations are maintained the representation can be effected by 

 some distribution of Hertzian oscillators. The radiation 

 from a resonator is the same as that from a Hertzian oscillator 

 whose axis coincides with the straight line joining the free 

 ends of the resonator, and therefore the radiation from a 

 free end is the same as the radiation from an end of the 

 oscillator. In the case of a terminated wire the radiation 

 from the free end may also be assumed to be approximately 

 the same as from an end of an oscillator, and the solutions of 

 both problems obtained on this hypothesis are in agreement 

 with the results of observation on resonators and terminated 

 wires in air. 



XLIV. Notices respecting New Books. 



Annuaire pour Van 1913. Publie par le Bureau des Longitudes. 

 Paris : Gauthier-Villars. Price 1 fr. 50 c. 



r FHIS Annual, following out the alternating programme which it 

 -^ has adopted in recent years, contains this year, besides the 

 usual astronomical tables, various tables relating to Metrology, 

 Exchange Geography, Statistics, and Meteorology. 



The special technical articles to which the reader will naturally 

 turn at first are by Commandant Eerrie on the application of 

 wireless telegraphy to the transmission of time signals, and by 

 M. Bigourdan on the eclipse of the sun on the 17th April, 1912. 

 But this volume contains also articles of more melancholy interest. 

 These are the memorial discourses of M. Deslandres and 

 M. Henri Poincare on the astronomer Eadau ; and alas ! the 

 orations of MM. J. Claretie,Lippmann, Painleve, Appell, Bigourdan, 

 and General Cornille on M. Henri Poincare himself ! " De quelle 

 immense proie la mort vient de se saisir ! " 



