abstracts: technology 137 



Massachusetts. A contour map on a scale of 1 : 250,000, printed in 

 colors, shows the principal drainage basins and the location of gaging 

 stations. C. H. P. 



ENGINEERING. — Accuracy of stream-flow data. N. C. Grover and 

 J. C. Hoyt. U. S. Geological Survey Water-Supply Paper 400-D. 

 Pp. 53-59. 1916. 

 Records of stream flow at different gaging stations vary in accuracy 

 with the permanence of the stage-discharge relation, the precision with 

 which the discharge rating curve is defined, the refinement of gage read- 

 ings, the frequency of gage readings, and the methods of applying the 

 daily gage heights to the rating table to obtain the daily discharge. 

 The contributing factors are so complex that it is generally not prac- 

 ticable to determine mathematically the probable error. A knowledge 

 of the approximate accuracy is needed to apply intelligently the records 

 to different uses; and a knowledge of the sources of error and their 

 relative effects on the accuracy of the records is essential to the 

 proper collection of data for different uses requiring different degrees 

 of accuracy. A study of the accuracy of the records to be collected 

 at any station, therefore, should begin with the reconnaissance for the 

 site and continue through the selection, establishment, maintenance, 

 and operation of the station, the computation and interpretation of 

 the data, and the preparation of the records for publication. 



N. C. G. 



TECHNOLOGY. — The resistance of an oil to emulsification. Winslow 

 II. Herschel, Bureau of Standards Technologic Paper No. 86. 

 Pp. 37. 1917. 

 In this paper is described a new test for the emulsification of oils. 

 Certain results obtained by such measurements are also discussed. 

 The test may be briefly described as follows: 20 cc. of the oil to be 

 tested and twice that volume of distilled water are heated to 55°C. 

 in a 100 cc. cylinder, 26 mm. inside diameter, and stirred for five 

 minutes at a speed of 1500 r.p.m. The cylinder and contents are 

 allowed to stand at the same temperature, and readings are taken at 

 more or less frequent intervals (according to the type of oil) of the vol- 

 ume of oil settled out from the water. From these readings, a maxi- 

 mum rate of settling, called " demulsibUity", is easily taken from a 

 table. The paddle is simply a plate of metal 8.9 by 20 by 1.5 mm. 

 Since the test is not sensitive to slight changes of paddle dimensions, 

 they need not be exact, and no calibration is required. 



W. H. H. 



