February 22, 1889.] 



SCIENCE. 



139 



of half a wave was found to be 30 centimetres. When a metallic 

 parabolic mirror, i metre across its opening, was placed behind the 

 apparatus used to produce the discharge, the action was propa- 

 gated to a distance of S metres ; and the action was greatly in- 

 creased when a second concave mirror was placed behind the 

 receiving apparatus. When a conductor was interposed, the action 

 ceased, while non-conductors allowed the waves to pass. By inter- 

 posing perforated metallic screens, it was found that the waves are 

 propagated in straight lines ; the waves passed through a dry 

 wooden partition. Polarization of the waves could be determined 

 in several ways. When the receiver was placed at right angles to 

 the apparatus producing the waves, no action between them could 

 be detected, the vertically produced waves not being picked up by 

 the horizontally placed receiver. When the two pieces of apparatus 

 were placed parallel to each other, and a wooden cube, with a 

 number of insulated metallic wire rings wrapped round it, was 

 placed in the path of the electro-dynamic waves, it produced the 

 same effect as does a tourmaline plate on polarized light. When 

 the wires were vertical, — that is to say, parallel to the exciting 

 apparatus, — the action was not propagated through the cube ; but 

 it was, on the other hand, when the wires were horizontal. When 

 the receiver with its mirror was placed horizontally, so that it did 

 not record any action as reaching it, and the wire arrangement 

 described above was placed in the path of the waves, no change 

 took place in the receiver when the wires on the cube were either 

 vertical or horizontal; but the receiver was affected when the wires 

 were placed at an angle of 45''. The laws of reflection of electro- 

 dynamic waves at metallic surfaces were found to be the same as 

 those for the reflection of hght at plane mirrors. Finally, Pro- 

 fessor Hertz has determined the refraction which the waves under- 

 go in a prism made of pitch, and finds that the refractive index of 

 this substance for electric waves is 1.68. Dr. Ritter demonstrated 

 by experiments the action of the ultra-violet rays of light on electric 

 discharges in accordance wilh the experiments of Hertz, Wiede- 

 mann, and Eberts. 



Light Motors for Aeronautic Experiments. — M. 

 Trouve has constructed several small and extremely light motors of 

 the Gramme and Siemens type, in order to carry out some aeronau- 

 tic experiments. One of these motors, while only weighing about 

 three ounces, is capable of developing .026 brake horse-power. All 

 the parts of the machine are of aluminum with the exception of the 

 magnets. This motor, which could be contained in a box 1.2 

 inches each way, is able to lift itself twenty-five yards a second by 

 means of a wire and a fixed support. A one-horse-power motor 

 constructed on the same lines would weigh barely eight pounds. 

 When furnished with a light screw, and attached to the arm of a 

 balance, the motor is able to lift its whole weight, when connected 

 with a source of electric energy equal to forty watts. In order to 

 facilitate his experiments, M. Trouve places his motor at one end of 

 a long lever capable of a vertical and horizontal movement about 

 its centre, the electrical connections being made with the motor 

 through the lever and its supports. 



Important Patent Decision. — In England the court of 

 appeals has just handed down its decision reversing the finding of 

 the lower court in the Edison incandescent lamp patent case. The 

 case had been decided against Edison, principally on the ground of 

 insufficient specification. This last decision upholds the Edison 

 patents, and puts the Edison Company in England in the same 

 position that it enjoys in Germany, where the patents have been 

 uniformly upheld. 



NOTES AND NEWS. 



The American Association for the Advancement of Science 

 will meet at Toronto, Aug. 27 to Sept. 3 ; the first general session 

 to be held on Aug. 28 ; the council meeting, on the 27th. 



— The thirteenth anniversary of the Johns Hopkins University 

 will be commemorated on Friday, Feb. 22, 18S9. The public ex- 

 ercises of the day will be held in the Mount Vernon Place Meth- 

 odist Episcopal Church at eleven o'clock. The public are invited 

 to attend, and no tickets of admission will be required. The exer- 

 cises in the church will close before one o'clock. The trustees, 



faculty, alumni, students, and gentlemen personally invited, will as- 

 semble at the university at half-past ten o'clock, and proceed in a 

 body to the church, where seats will be reserved for them. The 

 alumni of the university will have a social gathering with a lunch- 

 eon after the close of the exercises in the church. The physical 

 laboratory will be thrown open from eight to ten o'clock in the 

 evening to members of the university and their friends, and the 

 chief instruments and pieces of apparatus will be shown to visitors. 

 Professor Rowland will make an address to physicists in the hall 

 of the physical laboratory at half past four o'clock, on " Modern 

 Views with Respect to Electric Currents." Specials cards of ad- 

 mission will be required. Right Rev. Henry C. Potter, Bishop of 

 New York, preached the annual sermon before the Christian As- 

 sociation of the university in St. Paul's Church (corner of Charles 

 and Saratoga Streets) on Sunday, Feb. 17, at 8 P.M.: subject, "The 

 Mastery and Mastering of Circumstances." All members of the 

 university were invited to attend. The University Glee Club 

 gave a concert in the Lyceum Theatre on Tuesday, Feb. 19, at 

 8 P.M.: tickets, fifty cents. The Athletic Association gave a 

 gymnastic exhibition in the gymnasium on Thursday, Feb. 21, at 

 8 P.M. Tickets (fifty cents each) had to be obtained at the Univer- 

 sity Post-Office. 



— At a meeting of the American Oriental Society, held at Phila- 

 delphia, October, 1S88, Isaac H. Hall, Richard J. H. Gottheil, 

 George F. Moore, Edward W. Hopkins, and Cyrus Adler were ap- 

 pointed a committee to obtain information respecting manuscripts 

 that exist in America, written in the Oriental languages or coo- 

 nected with their study, with a view to the ultimate publication of 

 a comprehensive catalogue of the same, in a worthy manner, and 

 calculated to serve all the useful purposes of the Oriental catalogues 

 of the great libraries of Europe. The manuscripts which are the 

 subject of inquiry include all the ancient and modern languages 

 and dialects of Asia, with those of Egypt and Ethiopia, whatever 

 be the subject-matter of the manuscript, whatever be the character 

 of the writing for elegance or negligence, whatever be the material 

 upon which it is written, whatever be its state of preservation, or 

 whatever be its length or size. The points of inquiry include the 

 language of the manuscripts, if known ; the style of writing, or the 

 alphabet employed (as, if the manuscript be Arabic, whether in 

 Cufic or Neskhi, etc.; if Turkish, whether in Greek, Arabic, or Ar- 

 menian letters, etc.), and the material upon which written ; the size 

 and binding (or absence of binding) ; number of leaves, and other 

 external particulars of the manuscript ; or, if a roll, its dimensions, 

 and the number and dimensions of its columns (of fragments, 

 papyrus, etc., the mere dimensions) ; the history of the manuscript, 

 as far as known, and how it came into its present hands ; if the 

 manuscript is in a public library, both its present catalogue marks, 

 and information respecting any former labels, library marks, or 

 notes of ownership (the latter, of course, are desired if the manu- 

 script is in private hands) ; also the date of the manuscript, if 

 known. 



— The field-work of the irrigation survey of the arid region of 

 the United States is being vigorously prosecuted in Colorado and 

 New Mexico, notwithstanding many disadvantages arising from 

 cold and stormy weather. From Colorado, Mr. W. D. Johnson, in 

 charge, reports the completion of the Pueblo and Huerfano sheet 

 in fifty-foot contours, and on a scale of two miles to the inch, and 

 considerable work done on the Apishapa and Juniata sheets, all 

 being in the Arkansas valley. Mr. Johnson's parties, living in 

 tents, have experienced temperatures below zero, and encountered 

 twenty inches of snow : but such attention has been given to the 

 men, that, beyond a few frost-bites, no trouble has been experienced 

 in prosecuting work on every day not actually stormy. Work in 

 New Mexico on the Lower Rio Grande has been commenced ; Mr. 

 R. Henry Phillips in charge, reporting the arrival of his party at 

 El Paso, and the occupancy of points connecting this work with 

 the base-line measured near Fort Bliss in 1S7S by the United 

 States Engineers. 



— Mr. Edwin Chadwick, the pioneer of sanitar\' reform in Eng- 

 land, and indeed throughout the world, will, on the anniversary of 

 his ninetieth birthday, March 2, be presented with a congratulatory 



