.iPSTR.icrs ()/• /{/;/./. svsTr.M rr.cfixic.ir. r.ii'fiRS isi 



siTveil values ari- ohtaiiicil if prn|H'r \aliirs an- taki-ii for the fractioii.il 

 |x)\ver, tIeiTcasiiijj to one tltiril as tlio IoikIiicss iiicn-ases to JOO units. 



Correlation BchiCin Crack Dnrlopnti-nt in Class While Condtuling 

 Electrieity ami the Chemical Composition of the Glass.^ Karlk K. 

 StillMAUlKR. A stu(i\' was made of tiie susceplil)ility to craok 

 ilevelopnient shown l)y live ilitTerent kinds of glass when they were 

 suhjectctl to the action of an electric current. The results indicated 

 that the tendency to crack increased with increasing alkali content 

 of the glass and with increasing electrical con(lucti\it\'. 



Report of the Chairman of the Telegraphy and Telephony Committee 

 of the American Institute of Electrical Eni^ineers.^ O. B. Blackwki.i,. 

 This report gives a brief summary of the advances which have been 

 niatle or which have come into prominence in the communication 

 art during the year. Pajx-rs which have been presented before the 

 Institute and which, in general, lia\e recorded such advances are 

 reviewetl. 



Selective Circuits and Static Interference}" J. R. Carso.v. This 

 paper is an application of a general mathematical theory to the ques- 

 tion as to the possibilities and limitations of selective circuits when 

 employed to reduce "Static" interference. In the case of static 

 interference and random disturbances in general the random and 

 unpredictable character of the disturbances makes it necessary to 

 treat the problem statisticalh' and express the results in mean values. 

 In spite of the meagre information a\ailable regarding the character 

 and frequency' distribution of static, this treatment of the problem 

 yields general deductions of practical significance. The conclusion 

 is reached that for given signal requirements there is an irreducible 

 residue of static interference which cannot be eliminated. This 

 limit is closely approached when a filter of only two or three sections 

 is employed as the selective circuit, and only a negligible further gain 

 is made possible by the most elaborate circuit arrangements. A 

 formula is also given for calculating the relative figures of merit of 

 selective circuits with respect to random interference. 



The Guided and Radiated Energy in Wire Transmission}^ J. R. 

 C.VRSOX. This is a mathematical analysis of wave propagation along 

 guiding wires from the fundamental equations of electromagnetic 

 theorj-. It is shown that the engineering theory of wire transmission 

 is incomplete, and that, in addition to the transmitted wave of en- 



» Jour. .\ni. Chcm. Soc., \ol. XL\"I, No. 8, -August. 1924. 



'Journal of the .American Inst, of Elec. Engineers, \'(>l. 4.^, pas;o lOS.?, 1924. 



'° Trans. .A. I. E. E., 1924. 



" Jour. -A. I. E. E., Oct., 1924. 



