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LVII. Intelligence and Miscellaneous Articles. 



HERTZ WAVES AND METALLIC ENCLOSURES. 

 To the Editors of the Philosophical Magazine. 

 Gentlemen, 



AMONG- other misstatements made in this country I observe 

 one to the effect that electric waves of moderate length can 

 penetrate a complete metallic enclosure and affect a coherer inside. 

 As shown by me in 1894*, they can readily get in by insulated 

 wires, or by chinks or other interruption of metallic conductivity, 

 but into a cavity really bounded by a conducting wall of fair thick- 

 ness they do not go. 



The statement that they do is a purely misleading one, likely to 

 cause eminent continental physicists to surmise that there may 

 after all be some discovery involved in those sensational news- 

 paper accounts which have not scrupled to use the absurd phrase 

 " Marconi Waves " and to speak of them as if they were novelties 

 unknown to science. 



Yours faithfully, 



Oliver J. Lodge. 



ON THE VISCOSITY OF INSULATING LIQUIDS IN A CONSTANT 

 ELECTRICAL FIELD. RT G. QUINCKE. 



The results of this investigation are as follows : — 



I. If solid spheres of insulating material are made to oscillate in 

 an insulating liquid between condenser plates, either parallel or at 

 right angles to the lines of force, the oscillations will be the more 

 strongly damped, the greater is the charge on the plates of the 

 condenser. 



II. The difference of the logarithmic decrement of the oscillations 

 with a charged and an uncharged condenser, X— A , is a measure of 

 the increase of viscosity due to electric force, or a measure of 

 the electric viscosity of the liquid at right angles or parallel to 

 the electric lines of force. 



III. The electric viscosity at right angles to the lines of electrical 

 force is for ether, for carbon bisulphide, for a mixture of equal 

 volumes of carbon bisulphide and oil of turpentine, and for 

 benzole, nearly proportional to KP/a, where K is the dielectric 

 constant of the liquid, P the difference of potential, and a the 

 distance between the condenser plates. 



IV. Electric viscosity parallel to the electric lines of force is 1*5 

 to 6 times smaller than electrical viscosity at right angles to the 

 lines of force. — Wiedemann's Annalen, No. 9, 1897. 



* ' The Work of Hertz and his Successors,' published by the Elec- 

 trician Co., Salisbury Court, Fleet Street, London. 



