620 



SCIENCE 



[N. S. Vol. LI. No. 1329 



were of a very sensitive type. The records were 

 made toy an especially constructed moving-fihn 

 camera in connection with a string-galvanometer 

 capable of recording from sLx stations simultane- 

 ously, of the type used by our army for sound- 

 ranging. Stations were located at the muzzle of 

 the 'gun, and at points in front of the guns at dis- 

 tances of albout 100, 200, 300, 400, 500, 600, 1,000, 

 2,000, 7,300 and 21,000 feet, six of these stations 

 being used at one time. The locations were de- 

 termined with precision. Meteorological observa- 

 tions were made by special observers in the dfetant 

 stations and on the field near the guns, at >the time 

 of the experiments and continuous records were 

 made at the Proving Ground Headquarters and 

 at the United States Weather Bureau Station. 

 These observations covered temperature, barometric 

 height, humidity, wind velocity and wind direc- 

 tion. Measurements were also made of the velocity 

 of the sound at a series of stations located on a 

 line at right angles to the line of fire, and on a 

 line at 45° to one side of the line of fire. In all, 

 seventy-two sets of velocity determinations were 

 made, eleven sets extending to the most distant 

 stations at 21,000 feet from the gun, while the other 

 sets relate to Various groups of stations within 

 2,000 feet of the gun. Heretofore there has been 

 a general impression that explosive sounds travel 

 much farther than do ordinary sounds, the velocity 

 being perhaps several times the normal velocity. 

 These experiments show conclusively that the veloc- 

 ity at a distance of one hundred feet from a 10- 

 inch gun is about 1,240 feet per second, or 22 per 

 cent, above normal; at two hundred feet from the 

 gun the velocity is only about 5 per cent, above 

 normal. For all distances above five hundred feet 

 from the gun the velocity of the explosive sound 

 from the largest sized gun is practically normal. 

 The value of the velocity of sound over the long 

 range of 21,000 feet has not yet been calculated 

 with all corrections applied, the preliminary value 

 is in entire agreement with other determinations, 

 and is about 1,089 feet per second at the freezing 

 temperature. It is expected that the final value 

 will be of a precision equalling the best heretofore 

 obtained. 



The V. S. navy MV-type of hydroplione as an aid 

 and safeguard to navigation: Harvey C. Hates, 

 Ph.D., U. S. Naval Engineering Experiment Sta- 

 tion, Annapolis. (Introduced by Professor John 

 A. Miller.) 



The transient process of establishing a steady 

 alternating electric current on a long line from 



laboratory measurements on an artificial line: A. 

 E. Kennellt, A.M., So.D., director, Eesearch Di- 

 vision, Electrical Engineering Department, Massa- 

 chusetts Institute of Technology, and U. Nabe- 

 SHIMA. When a power-transmission electric con- 

 ducting line is switched on to the generator at the 

 power house, the alternating-current on that line 

 settles down to a final state, under steady load, in 

 a time which is theoretically indefinitely long, but 

 which is usually practically covered in a small 

 fraction of a second. The paper discusses the 

 transient phenomena which occur along the line 

 during this process of upbuilding the final current 

 and voltage. The subject has Ibeen studied theo- 

 retically by a number of writers; but very few 

 practical observations have been published con- 

 cerning this transient state. It is known that the 

 current and voltage do not build up steadily and 

 continuously, but advance by little jumps which 

 occur at regular short intervals of time, accom- 

 panying successive refiections of electromagnetic 

 waves from one end of the line to the other. The 

 authors present in the paper a number of observa- 

 tions which have been secured photographically, of 

 the rise of voltage and current on a long artificial 

 electric power-transmission line in the laboratory, 

 and have compared the observed rates of growth 

 with those which are indicated by theory, with a 

 fairly satisflaotory agreement. The observed re- 

 sults indicate the manner and mechanism by which 

 electric power may be conceived of as being trans- 

 mitted along such a line. 



The strephoscope : N. W. Akimopf. (Introduced 

 by Professor Eric Doolittle.) 



New features in the eclipsing variable TJ Cephei: 

 R. S. DuGAN, professor of astronomy, Princeton 

 University. (Introduced by Professor H. N. 

 Eussell.) Arthur W. Goodspeed 



(To be conchided) 



SCIENCE 



A Weddy Journal devoted to the Advaacement of 

 Science, publishing the official notices and pro- 

 ceedings of the Americetn Association for 

 the Advancement of Sei^ce 



Publi^ed every Friday by 



THE SOENCE PRESS 



LANCASTER, PA. GARRISON, N. Y. 



NEW YORK, N. Y. 



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