Mat 18, 1906.] 



SCIENCE. 



765 



of Tulane University. The following offi- 

 cers were elected to serve during the meet- 

 ing: 



Councilor — F. O. Marvin, professor of civil en- 

 gineering, University of Kansas, Lawrence, Kas. 



Member of the General Committee — G. W. Bis- 

 sell, professor of mechanical engineering, Iowa 

 State College, Ames, Iowa. 



Member of the Sectional Committee, 1906 to 

 1911 — J. B. Webb, professor of mathematics, 

 Stevens Institute of Technology, Hoboken, N. J. 



The secretary of the section was elected press 

 secretary. 



The vice-president of the section, Fred W. Mac- 

 Nair, president, Michigan College of Mines, 

 Houghton, Mich., served as chairman of the sec- 

 tion. 



Owing to the small number of members 

 in attendance, it was decided to combine 

 the programs of Sections D and B in two 

 joint sessions. These proved to be of gen- 

 eral interest and value. The report of the 

 papers offered in Section B will be found 

 on pages 415 to 421 of the issue of Science 

 for March 16, 1906. 



The first paper was read by Fred "W. 

 MacNair, president, Michigan College of 

 Mines, Houghton, Mich., and described 'An 

 Experiment on Easterly Deviation beneath 

 the Earth's Surface,' which he had made 

 in the No. 5 shaft of the Tamarack Mine. 

 A detailed report has already been pub- 

 lished on page 415 of Science. It might 

 be added, however, that the experiment of 

 dropping a steel ball from the top of a 

 shaft forty-two himdred feet deep and 

 finding it lodged in the timbers at a depth 

 of only eight hundred feet from the sur- 

 face, adds but another example to the gen- 

 eral experience that bodies which are 

 dropped in a mine-shaft seldom reach the 

 bottom. 



A paper by A. S. Langsdorf , professor of 

 electrical engineering, Washington Univer- 

 sity, St. Louis, Mo., on 'A New Type of 

 Frequency Meter,' was read by the secre- 

 tary and was published in The Electrical 

 World, Vol. 46, page 1029, for December 



16, 1905. The device was originally de- 

 scribed by the author.^ It was independ- 

 ently conceived by Mr. J. F. Begole, of 

 the Wagner Electric Manufacturing Com- 

 pany of St. Louis, and has recently been 

 placed on the market. The principle in- 

 volved in this instrument is based upon the 

 fact that if an alternating (sinusoidal) 

 electromotive force of E volts and fre- 

 quency o)(=2irn) is impressed upon a con- 

 denser of capacity C farads the current 

 will be 



I^E aC amperes. 



In other words, for a given value of C, 

 the indications of an ammeter will be pro- 

 portional to the frequency, provided E re- 

 mains constant, in which case the scale of 

 the ammeter could be graduated to read 

 directly in cycles. 



It is of course evident that the assump- 

 tion of constant electromotive force is not 

 justifiable where commercial circuits are 

 concerned. If the scale of the ammeter 

 mentioned above were graduated to read 

 cycles, a change in line voltage would be 

 recorded as an apparent change in fre- 

 quency. This difficulty can be overcome, 

 however, if the scale of the ammeter is it- 

 self movable and pivoted on a line coaxial 

 with that of the pointer or indicator of the 

 ammeter ; if the motion of the scale, due to 

 a change of voltage, is made equal to, and 

 in "the same direction as, that of the am- 

 meter needle, there will be no relative mo- 

 tion between the two, and the reading will 

 remain unaltered. 



To secure this compensating scale mo- 

 tion, the scale need only be attached to a 

 wound bobbin which is constructed in all 

 respects like that of an ordinary voltmeter, 

 this voltmeter winding being then con- 

 nected across the line. 



In the instrument as built the bobbin to 



' Proo. American Association for the Advance- 

 ment of Science, Vol. LIII., 1904, p. 380. 



