462 BELL SYSTEM TECHNICAL JOURNAL 



paper describes ami illustrates, with representative examples, various types 

 of common noise induction in order to lead to an understanding of their 

 nature. The paper includes, in addition, a discussion of simple remedies 

 which may be employed for representative cases of noise troubles due to 

 longitudinal induction. 



Mobile Radio. A. Bailey.^ A.I.E.E., Trans., V. 67, pt. 2, pp. 923-931, 

 1948. 



Stabilized Permanent Magnets.* V. P. Cioffi.' A.I.E.E.. Trans., V. 67, 

 pt. 2, pp. 1540-1543, 1948. 



Abstract — Permanent magnets are stabilized against forces tending to 

 demagnetize them, by partial demagnetization. It is shown that, after such 

 stabilization, the magnet operates at a point on a secondary demagnetiza- 

 tion curve. This curve may be treated identically as the major demagnetiza- 

 tion curve is treated in ordinary magnet design problems. Formulas are 

 developed for determining secondary demagnetization curves from the major 

 demagnetization curve when stabilization is achieved by magnetization of 

 the magnet before assembly, and by an applied magnetomotive force after 

 magnetization in assembly. 



It will be shown that, w'hen the magnet is partially demagnetized for the 

 purpose of stabilization, its operating point lies on a curve which, for con- 

 venience, will be called a secondary demagnetization curve. The object of 

 this paper is to discuss the derivation of secondary demagnetization curves 

 for given conditions of stability against demagnetizing forces and their 

 applications to magnet design problems. 



Relay Preference Lockout Circuits in Telephone Switching.* A. E. Joel, 

 Jr.! A.I.E.E., Trans., V. 67, pt. 2, pp. 1720 1725, 1948. 



Abstract — Occasions arise in telephone switching, particularly at com- 

 mon controlled stages, where calls compete for the use of equipment com- 

 ponents or switching linkages. These call requests for service are received 

 at random by circuits which must choose among and serve them on a 

 one-at-a-time basis. Circuits which perform this function are known as 

 "preference lockouts". E.xtensive use has been made of these circuits in 

 manual, panel, and crossbar switching systems. This paper describes the 

 design philosoj^hies of relay preference lockout circuits based on some of 

 these applications. 



Piezoelectric Crystals and Their Application, to Ultrasonics. W. P. Mason.' 

 Book, New York, Van Xostrand, 508 i)ages, 1950. 



Television Terminals for Coa.vial Systems.* L. W. Morkisox, Jr.' Elec. 

 Engg., \. 69, pp. 109 115, I'^ebruary, 1950. 



*A repriiU of tliis arlicic ni;i\ l)t' nhiaim-d on rt.'(|iR'st to the ociitor of the H.S.T.f. 

 ' B.T.I.. 

 •^ A. T. & 'I-. 



