ABSTRACTS OF TECHNICAL ARTICLES 517 



urements support the conclusion that the work function depends on 

 temperature. 



Fundamental Concepts in the Theory of Probability.- Thornton C. 

 Fry. Three commonly accepted definitions of the word " probability" 

 are discussed critically, with regard both to logical soundness and to 

 practical utility. Two major theses are presented: first, that each 

 definition has utilitarian merits which render it especially valuable 

 within its own field; second, that the objection of logical redundancy 

 which is so frequently raised against the Laplacian definition can 

 equally well be raised against the other two definitions. 



Wide-Range Recording.^ F. L. Hopper. The recent improvements 

 in sound quality resulting from the extension of the frequency and 

 intensity ranges are the results of coordinated activity in recording 

 equipment and processes, reproducing equipment, and theater acous- 

 tics. This paper discusses the recording phase of the process. A wide- 

 range recording channel consists essentially of the moving-coil micro- 

 phone, suitable amplifiers, a new recording lens, and certain electrical 

 networks. 



The characteristics of such a system, from the microphone to and 

 including the processed film, are shown. Other factors fundamentally 

 associated with wide-range recording, such as monitoring, film proc- 

 essing, the selection of takes in the review room, and re-recording, are 

 also discussed. The changes brought about by this system of recording 

 result, first, in a greater freedom of expression and action on the part 

 of the actor; and, second, in a much greater degree of naturalness and 

 fidelity than has been previously achieved. 



Iron Shielding for Telephone Cables^ H. R. Moore. Voltages of 

 fundamental and harmonic frequencies, induced along communication 

 cables by neighboring power or electric railway systems, can be reduced 

 by the electromagnetic shielding action of the sheath, if this is grounded 

 continuously or at the ends of the exposure. The shielding, particu- 

 larly at the fundamental frequency, is improved greatly by the pro- 

 vision of a steel tape armor, while a surrounding iron pipe conduit 

 effects a very great improvement at both the fundamental frequency 

 and the higher harmonics. 



This paper presents methods for the quantitative prediction of 

 the shielding, expressed by a "shield factor" or the fraction to which 



-American Mathematical Monthly, April, 1934. 



3 Jour. S. M. P. E., April, 1934. 



* Electrical Engineering, February, 1934. 



