86 Mr. E. H. Barton. Electrical Interference Phenomena 



in fact, it may perhaps be within the limits of the errors of observa- 

 tion. 



In Experiment IX. Here theory points to a distance apart of 38 cm. 

 as that which should produce 110 reflexion. The experiment, how- 

 ever, gave 66 cm. This discrepancy at first sight appears serious. 

 When, however, it is noticed that in the case of cylinders widely 

 separated a very great further increase in their distance is required to 

 produce a small decrease in their capacity, the discrepancy does not 

 seem so great. Indeed, when the distance between the wires in this 

 case is altered from 38 cm. to 66 cm., the capacity is only changed 

 by about 10 per cent. It is conceivable that a discrepancy of that 

 order might be due to the sloping portions of wire which served to 

 connect the normal wires, spaced at 8 cm., with the abnormal ones 

 spaced at 66 cm. 



SUMMARY OF CHIEF RESULTS. 



The principal conclusions to be drawn from the foregoing theory 

 and experiments taken in conjunction may be stated as follows : 



(1.) In experimenting with electrical waves of high frequency 

 passing along a pair of parallel wires with short-circuited end, 

 and containing a portion which produces partial reflexion, it is 

 necessary to make right choice of the lengths before and after 

 such source of reflexion in order to avoid disturbing inter- 

 ferences. 



.(2.) A sudden change in the capacity of the secondary produces a 

 partial reflection at that place of change. The ratio of the 

 amplitudes of the reflected and incident wave-trains may be 

 expressed as a simple function of the change in capacity. See 

 Equations (12) and (13) in the previous paper. 



(3.) If a sudden change in the capacity of the secondary is suc- 

 ceeded by a sudden reversion to the normal state of the wires, 

 then reflexions occur at each of these places of abrupt change. 

 And, if the distance between these two points is comparable 

 with a wave-length, then the waves proceeding from them will 

 interfere, consequently when the distance in question is in- 

 creased a series of maxima and minima successively obtain, 

 essentially analogous to those which simultaneously occur 

 in the optical phenomena known as Newton's Rings. 



(4.) If the secondary has a part which, though abnormal in appear- 

 ance, introduces no change in its capacity, then no reflexion is 

 produced by it. 



For each of the above statements theoretical grounds and experi- 

 mental confirmation have been adduced. And, although the two are 

 not in exact quantitative agreement, yet I think it will be admitted 



