14 abstracts: geology 



fixed point of the temperature scale below 0°C. This paper gives the 

 result obtained and describes in detail the method used at the Bureau 

 of Standards in making a redetermination of this constant. The 

 temperature measurements were made by means of platinum resist- 

 ance thermometers whose constants had been previously determined 

 by calibration at 0°, 100°, and 444. 6°C. (the boiling point of sulphur). 

 All the evidence at present available indicates that, down to — 40°C, 

 the platinum resistance thermometer, calibrated as above, defines 

 temperatures that are in agreement with those given by the standard 

 gas thermometer. The value, —38.87°, obtained at the Bureau is in 

 very good agreement with that found by Henning in 1913 at the 

 Reichsanstalt, Germany. He also used platinum resistance ther- 

 mometers and obtained -38.89°C. C. W. W. 



MAGNETISM. — The determination of the degree of uniformity of bars 

 for magnetic standards. Raymond L. Sanford. Bureau of Stand- 

 ards Scientific Paper No. 295. Pp. 14. 1916. 

 Magnetic standard bars are used for the calibration of permeameters 

 and for the comparison of methods of magnetic testing. One requisite 

 of such a bar is that it shall be magnetically uniform along its length. 

 If this condition is not fulfilled, errors may arise which can not be 

 calculated or eliminated from the measurements, and which may be of 

 considerable magnitude. In this paper it is shown how the degree of 

 magnetic uniformity of a bar may be determined from observations of 

 the distribution of magnetic leakage along the length of the bar when 

 it is magnetized between the poles of a suitable electromagnet. The 

 degree of uniformity is indicated by the values of the rate of change of 

 leakage along the length of the bar. Deviations of these values from 

 a constant indicate the presence of non-uniformities. An increase in 

 the value indicates a magnetically hard spot while a decrease indicates 

 a soft spot. The method may also be applied to the examination of 

 magnetic materials for mechanical inhomogeneities and for the detec- 

 tion of flaws. R. L. S. 



GEOLOGY. — Lode mining in the Quartzburg and Grimes Pass porphyry 

 belt, Boise Basin, Idaho. E. L. Jones, Jr. U. S. Geological 

 Survey Bulletin 640-E. Pp. 83-111, with 1 map. 1916. 

 The Boise Basin lies near the western edge of the irregular moun- 

 tainous area between the Salmon and Snake rivers in Idaho. The 

 basin structure is ascribed to the sinking of a fault block approxi- 



