316 Scientific Intelligence. 



6. Hertz's experiments on Electro-magnetic Waves. — Professor 

 Fitzgerald and Mr. F. T. Trouton have repeated Hertz's ex- 

 periments. Ordinary masonary walls were found to be transpar- 

 ent to electrical waves of ten meters in length, with an apparatus 

 suitable for dealing with definite angles of incidence. With a 

 wall three feet thick reflection was obtained, when " the vibra- 

 tor " was perpendicular to the place of reflection; "but none, at 

 least at the polarizing angle, when turned through 90° so as to 

 be in it." This decides the point in question, the magnetic dis- 

 turbance being found to be in the plane of polarization, the elec- 

 tric at right angles. — Nature, Feb. 21, 1889, p. 3 91. , j. t. 



1. Electrified Steam. — " Helmholtz has shown that if an in- 

 visible jet of steam be electrified or heated it becomes visible with 

 bright tints of different colors according to the potential or the 

 temperature." — Nature, Jan. 24, 1889. 



8. Viscosity of gases at high temperatures and a new Pyrome- 

 tric method. — The subject of the viscosity of gases has been in- 

 vestigated by Maxwell, O. E. Meyer, S. W. Holman and others. 

 Dr. Barus in a very exhaustive paper reviews the work of previous 

 observers, and adds valuable results on viscosity at high tem- 

 peratures. Obermayer had investigated the subject up to 280°, 

 Holman with carbonic acid to 224° and with' air to 124°, E. 

 Wiedeman at 100° and 185°. Dr. Barus has carried his observa- 

 tions to 1000°. Temperature was measured by the combination of 

 a porcelain air-thermometer and a thermal junction of platinum 

 and platinum-iridium. Further details of this method of measur- 

 ing high temperature are reserved for the forthcoming bulletin 

 No. 54, of the U. S. Geological Survey. The observations sug- 

 gest to Dr. Barus a method of measuring high temperatures 

 which is based upon Meyer's equation of gas transpiration. He 

 entitles the method transpiration pyrometry and gives a compari- 

 son of the temperatures measured by this method with those 

 obtained by a direct method, and believes that greater precision 

 in the measurement of high temperature can be obtained by this 

 method than by any other method, not even excepting the 

 method of the porcelain air-thermometer. The paper concludes 

 with a careful discussion of the results upon viscosity which the 

 author has obtained ; a plate giving diagrams of the apparatus 

 and the curves which represent the results accompanies the paper. 

 — Ann. der Physik und Chemie, vol. xxxvi, 1889, pp. 358-398. 



J. T. 



II. Geology and Natural History. 



1. Brachiospongidaz : On a Group of Silurian Sponges, by 

 Charles Emerson Beecher. 28 pp. 4to, with 6 plates. Mem. 

 Peabody Mus., Yale Univ., Vol. II, Part 1. New Haven, Conn., 

 1889. — The first known specimen of the Brachiospongidae was de- 

 scribed and figured, as Mr. Beecher states, by Troost in 1839, but 

 not named. It was from Tennessee. The same species and prob- 



