ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. 

 Each of the scientific bureaus in Washington has a representative authorized to 

 forward such material to this journal and abstracts of official publications should 

 be transmitted through the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



GEOPHYSICS. — Mechanics of the Panama Canal slides. G. F. 



Becker. U. S. Geological Survey Professional Paper 98-N. Pp. 



253-261, with 3 figures. 1916. 

 After describing the essential features of the breaks on the Culebra 

 Cut the author points out that there is a limit to the depth of a vertical 

 cut in an homogeneous isotropic mass, the upper surface of which is 

 plane. This limit is that at which the pressure is sufficient to produce 

 simple shear in the mass, and in a concluding note reasons are given for 



believing that 6 \ 2 multiplied by the resistance to such shear is about 

 equal to the ultimate strength under linear compression. The depth 

 at which one-sided relief of pressure will produce simple shear is called 



yv 



It is shown that in such a bank the profile of a surface along which 

 the mass is strained to the elastic limit must be a form of the elastic 

 curve, the directrix of which lies at a depth y±. 



The lowest or basal slide curve is one which intersects the horizontal 

 bank at right angles. Examples are worked out for this and other 

 cases. 



A complete analogy exists between the form of these curves and those 

 which the surface of water assumes when it rises by capillarity between 

 vertical, parallel glass plates. 



In view of these results the author discusses to some extent the for- 

 mation of ruptures, the bulging of the canal bottom, and the effect 

 upon pressure of the form of the banks. The paper includes a note 

 on finite strains. G. F. B. 



PHYSICS. — The freezing point of mercury. R. M. Wilhelm. Bureau 

 of Standards Scientific Paper No. 294. Pp. 6. 1916. 

 The temperature at which mercury freezes is of importance in ther- 

 mometry. It marks the lower limit to which mercurial thermometers 

 may be used, and its location, at about — 39°C, makes it of value as a 



13 



