580 



SCIENCE. 



[N. S. Vol. IV. No. 94. 



rent almost instantly, was adjusted in'tliese ex- 

 periments so as to have a natural period of 

 vibration of 8,500 complete periods per second. 

 Under these circumstances it can hardly be 

 questioned that the curves obtained represent 

 the actual variations of current in the circuit. 

 In measuring the oscillatory charge and dis- 

 charge of condensers. Dr. Millis has obtained 

 some beautiful curves, reproductions of which 

 accompany the article. The agreement between 

 the computed and observed period of oscilla- 

 tion is in most cases within two or three per 

 ■cent. Curves showing the effect of an iron core 

 in the self-induction coil are especially interest- 

 ing. The damping of the oscillations, caused 

 by the eddy currents developed in the iron, is 

 very noticeable, and it is found that a thin tube 

 of iron is as effective in producing this damping 

 as is a solid core. 



Admittance and Impedance Loci: By F. Be- 

 dell. This paper deals with the application 

 of the principles of geometrical inversion to the 

 graphical treatment of alternating current prob- 

 lems. As a result of the reciprocal relation be- 

 tween admittance and impedance Dr. Bedell 

 shows that it is always possible to proceed from 

 a polar diagram representing one problem, to a 

 second diagram which may be interpreted in 

 connection with what might be called the in. 

 verse problem. Several special cases are dis- 

 cussed, but their presentation here would carry 

 us beyond the limits of this extract. 



Visible Electric Waves: By B. E. Moore. 

 While repeating some of the experiments of 

 Lecher on stationary electric waves along wires 

 Mr. Moore found that under certain conditions 

 the whole wire became luminous, the nodes and 

 loops of the electric waves being clearly indi- 

 cated by the form ©f the hazy light surrounding 

 the wire. This article describes the conditions 

 under which the phenomena are obtained. 

 This method of showing the presence of elec- 

 trical waves will doubtless prove most instruc- 

 tive and useful for lecture illustration. 



Note on the Refractive Index of Water and Al- 

 cohol for Electric Waves : By J. F. Mohler. 

 The writer calls attention to a source of error 

 in experiments previously described by Prof. 

 Cole (Phys. Rev., Vol. IV., p. 50). 



Book Notices. Nernst : Theoretical Chemis- 

 try ; Landauer : Spectralanalyse ; Gage : Prin- 

 ciples of Physics, 



NEW BOOKS. 



Elements of Physics. Vol. II. Electricity and 

 Magnetism. Edward L. Nichols and Wil- 

 liam S. Franklin. New York and Lon- 

 don, The Macmillan Co. 1896. Pp. ix+ 

 272. $1.50. 



Alternating Currents and Alternating Current Ma- 

 chinery. Vol. II. DuGALD C. Jackson and 

 John Price Jackson. New York and Lon- 

 don, The Macmillan Co. 1896. Pp. xvii+ 

 729. $3.50. 



Problems in Elementary Physics. E. Dana 

 Pierce. New York, Henry Holt & Co. 

 1896. Pp. vii+194. 



A Manual of Quantitative Chemical Analysis. 

 Frederick A. Cairns. Third Edition. Re- 

 vised and enlarged, by Elwyn Waller. 

 New York, Henry Holt & Co. 1896. Pp. 

 xii+427. 



Irigonometry for Beginners. By Rev. J. B. 

 Lock. Revised and enlarged by John A. 

 Miller. New York and London, The Mac- 

 millan Co. 1896. Pp. 147+ 63. $1.10. 



The Report of the Michigan Board of Agriculture, 

 1895. Pp. 900 



General Principles of Zoology. Richard Hert- 

 wiG. Translated by George W. Field. 

 New York, Henry Holt & Co. 1896. Pp. 

 xii+226. 



The Suman Body. H. Newell Martin. Seventh 

 edition, revised. New York, Henry Holt «fc 

 Co. 1896. Pp. vii+685. 



A Handbook of Rocks for Use without the Micro- 

 scope. James Furman Kemp. New York, 

 Printed for the author. 1896. Pp. vii+176. 

 $1.50. 



Pioneers of Science in America. Reprinted with 

 additions by William Jay Youmans. New 

 York, D. Appleton&Co. 1896. Pp. viii+508. 



Erratum : In the report of the papers read by 

 Prof. D. T. MacDougal before Section G., A. 

 A. A. S. , the last two paragraphs (on page 

 624) should be placed after the first para- 

 graph on the second column on page 435. 



