184 Lord Armstrong. On a Multiple Induction 



wires, the strong emanations from the positive wire and the feeble 

 ones from the negative, are shown in this figure, as well as in most of 

 those which are to follow. 



No. 2 may be regarded as a transverse section of No. 1, being pro- 

 duced bj similar sparks delivered vertically through a hole in the 

 dust plate when fixed horizontally midway between the sparking 

 points. It shows that the discharge is surrounded by circular lines 

 in the transverse as well as in the longitudinal direction. 



No. 3 is a similar transverse section taken a little in front of the 

 positive point. 



No. 4 is the same thing taken immediately in front of the negative 

 point. 



No. 5 is taken transversely immediately behind the positive point, 

 and shows the radiations issuing from that part of the wire. 



No. SA shows similar radiations from the positive wire at a distance 

 of about 12 feet in rear of the sparking point. 



No. 6 was produced by a succession of discharges from four 

 J-gallon Leyden jars joined up in pairs, two in parallel and two in 

 series. It will be observed that the circular lines are much more 

 strongly developed than in the preceding figures, but that the radi- 

 ations from the wires are less so. 



No. 7 was produced in the same manner, and shows the circular 

 lines still more highly developed. 



No. 8 is the transverse section of No. 7 taken in the same manner 

 as No. 2. 



No. 9 is the same as No. 7, except that t]ie conducting wires are 

 brought down upon the card at a steep angle. 



No. 10 was produced with battery discharges in the same manner 

 as No. 6, but with a short wet string introduced to soften the dis- 

 charge. This had the effect of greatly increasing the radiations both 

 from the positive and negative wires, while it reduced the develop- 

 ment of the circular lines. 



No. 11 was produced under the same conditions as in the preceding 

 case, except that the wet string was considerably lengthened. 



No. 12 was similarly produced, but with a still further increase in 

 the length of the wet string. 



No. 13 was produced without any visible discharge across the dust 

 The same battery was used as in the last and several pre- 



ling cases, but the Leyden jars were allowed to leak sufficiently to 

 prevent their reaching the sparking point. The same effect mav be 

 produced by taking the discharge at a by-pass with a shorter spark- 

 ing gap than that on the dust plate. 



No. 14. In this case the battery was discarded and sparks only 



x>m the combined coils were used, the same as in No. 1. It shows 



the effect of splitting the positive current by the use of a double wire 



