April 11, 1913] 



SCIENCE 



569 



The Coast and Geodetic Survey has recently 

 made an adjustment of the different loops or cir- 

 cuits or leveling forming the precise leveling net 

 of the United States, which will give the most 

 probable values for the elevations of bench marks. 

 The datum used is mean sea level, and it is as- 

 sumed that the mean levels of the Atlantic, Gulf 

 of Mexico, and Pacific are in the same level sur- 

 face. Deviations from this condition, if there are 

 any, are not greater than the accumulated errors 

 in a line of leveling joining any two of these 

 bodies of water. 



There are 44,720 kilometers (27,790 miles) of 

 leveling, run in two directions, and about 10,700 

 permanent bench marks involved in the precise 

 leveling. There is now precise leveling in all ex- 

 cept seven states in the United States and the net 

 is of such strength that the elevations resulting 

 from the recent adjustment will probably be held 

 as standard elevations for an indefinite time. 

 This will be a great benefit to surveyors and engi- 

 neers who experience great difficulties when the 

 elevations of bench marks are changed or placed 

 on different data. Theoretically, with each new 

 loop added to the level net, new and better values 

 for each bench mark may be obtained by an elab- 

 orate adjustment of the net, but the change from 

 the old value would, in nearly all cases, be ex- 

 ceedingly small and insignificant, as far as engi- 

 neering and surveying needs are concerned. The 

 plan adopted by the Coast and Geodetic Survey 

 is to hold fixed the old leveling and to fit any new 

 sections to it. From time to time adjustments of 

 the net will be made from which to obtain the 

 theoretically best values of the junction points in 

 the net, which will be of scientific interest only, 

 and tke resulting elevations would be needed for 

 surveying and engineering purposes. 



The Use of Logarithmic Coordinates in the Labo- 

 ratory : D. MoOMAW, assistant professor, applied 

 mechanics and hydraulics. Case School of Applied 

 Science. 



Presentation of diagrams, showing, on log- 

 arithmic cross-section paper, the method of deter- 

 mining the coefficients and exponents of curves 

 of the second and third degrees, such as represent 

 sometimes the relations between physical quantities 

 in experimental work in the engineering or physics 

 laboratory. 



The observed values are plotted on logarithmic 

 paper and the method applied simply and quickly. 



The Michigan Industrial Compensation Act: G. W. 



BissELL, dean of engineering, Michigan Agri- 

 cultural College. 



The most striking as well as the strongest fea- 

 ture of the law is that, except for farm and domes- 

 tic help, the defenses of contributory negligence, 

 negligence of fellow servant and assumption of 

 inherent risks, are denied to the employer. The 

 workingmen 's compensation and employers ' liabil- 

 ity act has been in operation in this state about 

 two and one half months, and so far the material 

 provisions of the law and the machinery provided 

 for its operation seem to be well adapted to carry 

 out and make effective the general purposes of the 

 statute. It is a well-constructed and workable act 

 in its general features, and should be given a fair 

 trial in its present form before any attempt is 

 made to materially amend it. The general ac- 

 ceptance and approval of the law by a vast major- 

 ity of the employers of labor in the state, and its 

 approval by workingmen generally, constitute per- 

 suasive evidence that the act in its present form 

 substantially meets the requirements and performs 

 the functions intended. 

 Oalifomia Electric Furnace Pig Iron: P. C. 



Langenberg, Athens, Ohio. 



A brief account of electric furnace reduction in 

 California and Sweden is given with a comparison 

 of the practices in the two countries. A brief out- 

 line is given of the California furnace: (1) de- 

 scription of the furnace and electrical equipment, 

 (2) operation and product of the furnace. 



Part Two deals with a microscopic study of pig 

 irons. Two samples of California iron are dis- 

 cussed and their chemical and physical properties 

 predicted by the aid of the microscope. These pre- 

 dictions are confirmed by analyses. The influence 

 of the rate of cooling on the size of the graphic 

 flakes is also shown. 

 Present Status of the Gas Turbine Problem: F. 



C. Wagner, professor of mechanical engineering. 



Rose Polytechnic Institute. 



It seems probable that with the gas turbine, as 

 in the case of the steam turbine, the most profitable 

 field will be in large units, when large volumes can 

 be handled with a relatively small machine. In 

 large installations, also, it would be worth while 

 to install apparatus for saving the heat in the 

 exhaust gases. 



Altogether the gas turbine art has made substan- 

 tial progress during the past year and the outlook 

 for practical development in the near future seems 

 especially favorable. 



