﻿590 



Prof. J. A. Fleming on tlie Electric 



We may consider the oscillator as constructed in the 

 following manner. Imagine a rectangular circuit ABCD of 

 wire (see fig. 2) placed perpendicularly to the earth's surface. 



®, 



®, 



and let it be traversed by a high frequency oscillation. Then 

 if a horizontal line is drawn through the centre of the rect- 

 angle and two points b and a chosen at equal distances on the 

 right and left side, the magnetic force at those points will be 

 equal and normal to the plane of the rectangle. If at any 

 instant the current is flowing counter clockwise round the 

 circuit, the magnetic forces H at these selected points will be 

 directed away from the spectator *. Next suppose a. wire to 

 be placed in contiguity to one side of the rectangle and to be 

 traversed by an equal current the same at all points of its 



Fi£. 3. 



® h' 

 ® H 



a 



Oh 

 b 



length and always in opposite phase to that in the side of the 

 rectangle adjacent to it (see fig. 3). 



* Tt is convenient sometimes to represent an end-on view of a tube or 

 line of electric or magnetic force. We then must indicate in some way 

 the directiun of the force whether to or from the spectator. This mar 

 he done by representing the section of the tube by a small circle and 

 putting a dot in the circle if the force is towards the reader, and a cross 

 on it if it is away from the reader, as is done to denote current directions 

 in similar diagrams in other cases. 



