THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. I. — The Variation of Potential along the Transmitting 

 Antenna in Wireless Telegraphy ; by C. A. Chant. 



I. Introduction. 



In a former paper* illustrations were given of the manner 

 in which standing waves are formed on a free-ending wire 

 when the electrical disturbance is produced by electrostatic 

 induction from a Hertzian oscillator at the other end of the 

 wire. The present communication contains a somewhat de- 

 tailed account of an examination of the aerial wire used to 

 radiate the waves in w T ireless telegraphy ; and,, in a section at 

 the end, a brief account of a continuation of the former experi- 

 ments. 



The problem of the electrical oscillations about a free-end- 

 ing wire has been treated from a rigid theoretical basis by 

 Abraham, f who determined the electric and magnetic forces 

 at any point in the field by directly integrating the Maxwel- 

 lian equations. For the purposes of analysis the wire was 

 considered to have the form of a very elongated paraboloid 

 of revolution, and the field to vary in such a way that the 

 electric lines of force ended perpendicular to its surface. 

 Sarasin and de la Rive,J and others had compared the oscilla- 

 tions about a wire to those in an open pipe ; but, as Abraham 

 remarks, though the relations are essentially similar, the anal- 

 ogy must not be pushed too far, In the pipe the radiation is 

 from within outwards, and is greatest in the direction of the 



* C. A. Chant, The Variation of Potential along a Wire Transmitting 

 Electric Waves ; this Journal, xv, p. 54, 1903; Phil. Mag. [6], v, p. 331, 

 1903. 



fM. Abraham, Ann. der Physik, ii, p. 32, 1900. 



\ E. Sarasin and L. de la Eive, Archives des Sciences Physiques et Natu- 

 relles, Geneve, xxiii, p. 113, 1890. 



Am. Jour. Sci.— Fourth Series, Yol. XVII, No. 97.— January, 1904. 



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