370 



SCIENCE. 



[N. S. Vol. III. No. 62. 



Very full and complete indices of subjects 

 and authors conclude the volume. 



The time and labor expended merely in the 

 collection of the material contained in this 

 publication must have been enormoiis. Some 

 faint conception of this may perhaps be gained 

 on learning that no less than two thousand two 

 hundred and twenty-two authors are referred 

 , to or quoted in its pages, exact reference to 

 their writings being given in all cases. 



The style throughout is scholarly and lucid. 

 The treatment of the subject-matter is fair and 

 impartial. No pains have been spared to make 

 this work a standard one; beyond question, von 

 Lippmann's Chemie der Zuckerarten is a classic 

 of chemical literature. 



Feedinand G. Wiechmann. 



SCIENTIFIC JOURNALS. 

 AMEEICAN JOURNAL OF SCIENCE. 



The March number contains three articles 

 upon the subject of the Eontgen rays, which 

 has excited so much interest during the past 

 month. The first of these is by A. W. Wright. 

 After a brief history of the subject, the author 

 describes in some detail the experiments which 

 have been performed at the Sloane physical 

 • laboratory in New Haven. These have yielded 

 results similar to those described elsewhere, 

 but with a remarkable degree of refinement. 

 Examples are given of a picture made from an 

 aluminum medal, in which the relief on both 

 sides is shown, also the lettering and milling 

 around the edge. It is stated that in the origi- 

 nal negative it is almost possible to decipher 

 the individual letters. The details are given 

 of the special methods which have been found 

 most successful in j'ielding good results. Some 

 of the typical pictures obtained are given on 

 an accompanying plate. A second plate shows 

 the impressions given upon a sensitive surface by 

 diverging stream lines through two parallel 

 slits in a copper plate. Three experiments 

 were performed : first, with both slits open 

 simultaneously ; second, with only one open at 

 a time, so that the streams were independent ; 

 and third, with the two streams passing by 

 a powerful magnet. The first two showed 

 very little, if any, distinct action between the 



streams themselves as regards their direction. 

 The effect of the magnet in the third case was 

 also negative. In another experiment, how- 

 ever, in which a very thin gold leaf was inter- 

 posed in the path of the rays, a deflection by 

 the magnet of about half a degree was observed, 

 due to the loading of the streams with metallic 

 particles ; the mutual repulsion of the streams 

 was also clearly shown. In all these cases the 

 rays were proved by measurement to leave the 

 surface of the glass of the vacuum tube nearly 

 normally. The article closes with a quotation 

 from an earlier paper (1870) by the same author, 

 upon electrical shadows from the Holtz machine, 

 to a certain extent anticipating the results that 

 have recently excited so much interest. 



The paper by Trowbridge shows how pieces 

 of metal can be located, for example, in the 

 human body by cathode photography, based 

 upon a principle analogous to that employed in 

 the Rumford photometer. He used two Crookes' 

 tubes with two terminals at an angle with each 

 other, and excited by a Tesla coil. The author 

 states that by use of the Tesla coil he has suc- 

 ceeded in obtaining pictures in less than a 

 minute. The destruction of the tubes is pre- 

 vented by placing them in a vessel filled with 

 paraiBne oil, while the oil is cooled by snow or 

 ice placed outside. 



The third article, by H. A. Rowland, W. R. 

 Carmichael and L. J. Briggs, discusses briefly 

 the sources of the rays. By using a tube of a 

 very high degree of exhaustion it was demon- 

 strated conclusively that the main source of the 

 rays was a minute point on the anode nearest' 

 to the cathode. At times a minute point of 

 light appeared at this point but not always. 

 Added to this source the whole of the anode 

 gave out a few rays. From the cathode no 

 rays whatever came; neither were there any 

 from the glass of the tube where the cathode 

 rays struck it as described by Rontgen. ' 'In the 

 other tubes there seemed to be diffuse sources, 

 probably due in part to the oscillatory dis- 

 charge, but in no case did the cathode rays 

 seem to have anything to do with the Rontgen 

 rays. ' ' 



The first article of the number is by J. B. 

 Hatcher upon 'Recent and Fossil Tapirs.' 

 In this he gives a detailed description of the 



