206 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1951 



Ultra-High Vacuum Ionization Manometer. J. J. Lander.^ Rev. Sci. In- 

 struments, V. 21, pp. 672-673, July 1950. 



Abstract — This note describes an ionization menometer which indicates 

 pressures more than two decades below the lower limit usually encountered 

 at about 1 X 10"^ mm of Hg with other manometers. This limit depends on 

 the design of the gauge; however, values reported for various gauges do not 

 differ much from that given above. Commonly the limit is observed as a 

 lowest reading obtained despite recourse to more or less drastic methods of 

 producing lower pressures, or a variety of changes in gauge design. The 

 flash filament method of pressure measurement has been used to measure 

 lower pressures and at the same time to indicate the lower limit of an ioniza- 

 tion guage. 



Metallized Paper for Capacitors.* D. A. McLean.^ I.R.E., Proc, v. 38, 

 pp. 1010-1014, Sept., 1950. 



Abstract — Metallized capacitor paper is attracting widespread interest 

 as a way of reducing capacitor size. In metallized paper capacitors, the usual 

 metal foil is replaced by a thin layer of metal evaporated onto the surface 

 of the paper. Lacquering the paper prior to metallizing increases the dielec- 

 tric strength and insulation resistance, reduces atmospheric corrosion of 

 the metal, and diminishes the rate of loss of electrode metal by electrolysis. 

 Owing to the extreme thinness of the metal layer, metallized paper capacitors 

 are subject to a type of failure not ordinarily found in conventional capaci- 

 tors. This type of failure consists of the loss of electrode by electrolysis and 

 occurs under d-c. potential when the ionic conductivity is high, as results, 

 for example, from the presence of moisture. For this reason, it is recom- 

 mended that special precautions be taken to keep the ionic conductivity 

 low, in particular with respect to thorough and effective drying and sealing 

 of the capacitor units. 



Thernwelastic Stress Around a Cylindrical Inclusion of Elliptic Cross 

 Section. R. D. Mindlin^ and H. L. Cooper.^ //. Applied Mech., v. 17, pp. 

 265-268, Sept. 1950. 



Abstract — ^The two-dimensional equations of thermoelasticity are solved 

 for the case of a uniform temperature change of an infinite medium con- 

 taining a cylindrical inclusion of elliptic cross section. The problem is 

 treated as one of plane strain in elliptic co-ordinates, and the solution is 

 given in closed form. Formulas and curves are given for the maximum values 

 of various components of stress at the interface between the inclusion and 

 the surrounding medium. 



Magnetostriction of Permanent Magnet Alloys.* E. A. Nesbitt.^ Bibliog- 

 raphy. Jl. Applied Phys., v. 21, pp. 879-889, Sept. 1950. 



* A reprint of this article may be obtained on request to the editor of the B. S.T.J. 

 » B.T.L. 



