Dr. A. G. J. Holt has drawn the attention of the Editor to a number of errors which appeared in his article in Issue 1. These arose since, due to lack of time, it was not found possible for authors to check the proofs of the articles in Issue 1. This work was undertaken by the Editorial Staff.
Page 49 Last line should read: ‘Referring back to equation (12)’
Page 50 Equation (17) to read: 
Page 50 Equation (19) to read: 
Page 50 Line above equation (22) to read: ‘equation (21) by cosh V gives’
Page 53 Equation (30) to read: 
Page 53 The last term in the second part of equation (31) to read: 
Page 54 Fourth line from the bottom of the page to read: ‘right to the positions marked Δ on Fig. 9, a full ripple appears in the magnitude response and’