ABSTRACTS OF TECHNICAL PAPERS ' 157 



set and read off its economic impedance in the same way that an 

 engineer can test a transformer. 



He has to take instead the observed fluctuations in time of two 

 series, say "wholesale commodity prices" and "commercial paper 

 rates, " and try to infer from such data the way in which changes in 

 one of these quantities react on the other. The paper is concerned 

 with the general way of doing this with a full analysis of the relation 

 between these two economic variables from this point of view. 



Just as most of the theory of oscillatory systems in mathematical 

 physics is confined to linear systems, so the writer finds it convenient 

 to assume linear relations between the economic variables. This 

 greatly simplifies the mathematics. The formulas come out to be 

 analogous to some formulas of electric circuit theory when approached 

 from the Heaviside operational standpoint. It thus appears that 

 much alternating current theory may come to be of value in studying 

 economic variations. It is pleasant to think that some years hence 

 we may be using the language of "a.c." theory (reluctance, susceptance, 

 impedance, etc.) to describe the functional relation of one economic 

 unit to the rest of society. Perhaps to study the relation of conditions 

 in one part of the country to those in another we shall be using the 

 long line transmission theory. Perhaps the theory will show us how to 

 build economic band-pass filters which will protect us from too great 

 fluctuations in business conditions, etc. 



The application of the ideas of oscillatory systems to economics, 

 here well started, is a subject which, it is believed, will strike a re- 

 sponsive chord in the heart of every electrical engineer and every 

 mathematical physicist. 



Contributions of Chemical Science to the Communications Industry.^ 

 Clarence G. Stoll. The author considers the improvements that 

 have been made under a four-fold grouping of materials into elec- 

 trically conducting, magnetic, insulating, and materials for apparatus 

 structures. Particular emphasis is laid on the influence the chemist 

 has exerted on the control of materials for manufacturing purposes. 

 So many undesirable variations in manufactured products are caused 

 by lack of uniformity in the raw materials that the aid of the chemist 

 in standardizing testing and sampling methods cannot well be over- 

 estimated. 



In conclusion, he pays homage to the readiness with which chemists 

 have responded to demands for improvement in many of the raw 

 materials and suggests that because of it similar demands may be of 

 ^ Journ. Ind. and Engr. Chem., \'ol. 19, p. 1132, 1927. 



