NATURE 



[May 4, 191 1 



Mr. G. S. Mwrill, of the National Elcrtric Lamp A««ocin- 

 tion, Cleveland, Ohio. The propcrtim dealt with are tli<- 

 resintancc, molting point, cmiskivity, and niechanicul 

 strength, and the tungntcn filament rpccivcs most attention. 

 The strength Ik determined by loading a short length of 

 liiamcnt placed on two knife edges half a centimetre apart, 

 at a point half-way between the sup|MirtK, and measuring 

 the depression under increasing load till the filament breaks>. 

 The change in the structure of the filament from a mixture 

 of finely-divided tungsten and binding m.nterial, to pure 

 crystalline tungsten as the temperature is raised during 

 manufacture, is well shown by a scries of micro-photo- 

 graphs. The effect of use in increasing the size of the 

 crystals and in roughening the surface of the filament is 

 shown in the same way. These changes are accompanied 

 by a decrease in strength of the filament, which occurs 

 njainly in the first loo hours of use. The conclusion drawn 

 from the observations is that a compact fine-grained struc- 

 ture is most desirable in lamp filaments. 



.\n extension for a further term of seven years of the 

 major part of Sir Oliver Lodge's patent No. 11,575 of 1S07 

 for " Improvements in Syntonised Telegraphy without Line 

 Wires " has recently been granted as a result of a case 

 argued before Mr. Justice Parker, the e.xtension being 

 a!k>wed mainly on tlie grounds that the patentee had not 

 been adequately remunerated for his invention. The patent 

 covers the radiating and receiving apparatus of a complete 

 system of wireless telegraphy and the methods of tuning 

 the sending and receiving circuits to the same frequency, 

 and describes how messages may be sent to each of a 

 numl>er of suitably tuned receiving stations by change of 

 the frequency of the oscillations that are generated. The 

 aerials described are of different forms, but all consist of 

 a pair of " capacity areas " connected by inductances the 

 magnitudes of which control the period of oscillation. The 

 eleven claims of the specification are concerned with the 

 insertion of these inductances into the radiating and 

 receiving circuits ; with the adaptation of a single aerial 

 for .sending and receiving the insertion in turn of induct- 

 ances of various magnitudes in order to attain the 

 selectivity already referred to; with the details of a coherer 

 consisting of a fine metal point resting on a flat metallic 

 spring ; and, lastly, with methods of setting up the oscilla- 

 tions by discharges into the oscillator across air-gaps and 

 receiving through an oscillation transformer, in order to 

 separate both the oscillator and the resonator from metallic 

 connection with other circuits, thus enabling them to 

 vibrate in their own free periods so as to get precise 

 tuning. The whole specification has been extended for the 

 further term except the portions covering the use of the 

 same circuits for sending and receiving, the use of various 

 frequencies to select various receiving stations, and the use 

 of the particular form of coherer. It thus appears that 

 the patentee holds a master-patent covering the tuning of 

 elwtrical circuits by means of inductances, and as the use 

 of such tuned circuits is common to methods of signalling 

 used by wireless telegraph companies operating in England, 

 the sitii.itioii will probably give rise to interesting develop- 

 ments. 



The report of the council of the Hampstead Scientific 

 Society for the year 1910 shows that the object for which 

 the society was founded in 1899, namely, the encourage- 

 ment of a popular interest in science, has been pursued 

 diligently and successfully. During the year eighty new 

 members were elected, the membership rising to 334. the 

 largest in the history of the society. Twenty-nine meet- 

 ings, general and sectional, were held in 1910, in addition 

 to five vacation meetings, a summer excursion organised 

 NO. 2166, VOL. 86] 



by the photographic >--ciion, and four Chrictmas lectu.^. 

 ! to juveniles. Tlie feature of the society's work for th«i 

 year was the <levek>piiu;nt of the astronomical MCtton *voiotit 

 tite cttablichment of the obser\'atory near the Whit«ctoiMr 

 I'ond. The meteorological station at the same place has 

 Ijeen efficiently conducted. An observer attended .i" 

 q a.m. and 9 p.m. evTy day during the year, without 

 intermission, and the results, after reduction, have \n".\ 

 published monthly by the Meteorok>gical OfSce. 



The Carnegie Institution of Washington has 

 list of the various works which it has published, 

 with those it has in the press. Copies of each pul>... .....j^.,. 



except the Index Medicus, are sent gratuitously to a 

 limited number of the great libraries of the world, and 

 the remainder of the edition is on sale at cost price. As 

 the catalogue shows, this arrangement enables workers in 

 science to obtain accounts of many important researches 

 at a minimum cost. Descriptive lists of the books avail- 

 able will be sent to any interested person on application 

 to the Carnegie Institution of Washington, Washington, 

 DC. 



A SUPPLEMENT— covering works added to the library 

 during the years 1908-9 — to the Catalc^ue of Lewis's 

 Medical and Scientific Circulating Library has been 

 issued from the library at 136 Gower Street, London. 

 The catak^ue, the price of which is sixpence, contains a 

 classified index of subjects with tlie names of the authors 

 who have treated upon them, in addition to the ordinary 

 alphabetical list of titles. 



OVR ASTRONOMICAL COLUMN. 



New Minor Planets. — A Central News telegram of 

 Tuesday states that the Transvaal Observatory reports the 

 discovery of two minor planets. The discovery ' was made 

 during an attempt to phot<^raph the eighth satellite of 

 Jupiter. TJie following are the positions of the new 

 planetoids: — No. i, R..A. i4h. 41m., Dec. 12° 34' S. ; 

 No. 2, R.A. i4h. 48m., Dec. 15° 18' S. It is stated that 

 these are the first minor planets found by an obser\atory 

 south of the equator. 



Nov.\ Lacert^. — Photometric measures of Nova 

 Lacertae, made between January 4 and March 15 by Mr. 

 H. Shapley at the Laws Observatory, are recorded in No. 

 4493 of the Astronomische Sachrichten. During that 

 period there was a general decline of brightness from 

 mag. 7-67 to mag. 923. Four neighbouring B.D. stars 

 were used for comparison, and it is suggested that one of 

 them, B.D. + 51° 3420 (mag. 8-7), is a variable with a range 

 of at least 04 magnitude ; if this is so, several anomalies 

 in the photometric results may be explained. 



In the same journal Dr. Slocum records observations of 

 two coloured B.D. stars near the nova, to which M. Luizet 

 previously directed attention and suggested that B.D. 

 + 51° 3414 diminished in brightness by 1-5 magnitudes 

 between January 2 and February 21. The photographic 

 observations at Yerkes, with coloured screens, indicate that 

 both stars are abnormally cokxired, B.D. -^5I° 3416 show- 

 ing a greater preponderance of red rays and B.D. 

 + 51° 3414 a greater preponderance of rays of shorter 

 wave-length than a normal star of the A type. 



Halley's and Fa\x's Comets. — .\n obser\-ation by Prof. 

 Barnard, using the 40-inch refractor, showed that on 

 March 19 Halley's comet was of magnitude 135, and very 

 easy to obser\-e. It was round, and the middle showed a 

 slight brightening, with possibly a faint, but uncertain, 

 nucleus ; its measured diameter, probably too large, was 

 45' {Astronomische Sachrichten, No. 4492). 



Dr. Ebell continues his ephemeris, giving places and 



magnitudes for Faye's comet (1910^) up to May 14. At 



. present the comet is about 20 m. and slightly north of 



