November 20, 1902] 



NA TURE 



67 



the colour of the Nova was recorded as " a pale bluish white " 

 on each occasion. 



However, further observations, made on October 6, 7 and 

 14, indicate that the Nova has now assumed a bluer colour than 

 hitherto observed, and that the visual focus is now about o '2 

 inch greater than that of a star, that is to say, it now corre- 

 sponds with the visual focus for planetary nebulse. Prof. 

 Barnard is certain that this change has taken place since 

 August 29 of this year (Aslrophysical Journal, vol.xvi. No. 3). 



New Minor Planets. — In No. 3826 of the Astronomische 

 Nachrichten, Prof. Max Wolf records yet another batch of seven 

 new minor planets, all of which were discovered, photographic- 

 ally, on October 25. 



The planet 1902 K.E., discovered on October 25, has since 

 proved to be identical with (19) Fortuna, the previously pub- 

 lished ephemeris of which was incorrect. A new ephemeris is 

 now given. 



The minor planets (477) [1901 G.R.] and (47S) [1901 G.U.], 

 discovered by Dr. Camera, have been named Italia and Tergeste 

 respectively. 



Observations of the Aurora.— A very interesting and 

 valuable series of observations of the Aurora, which have been 

 made at the Yerkes Observatory during the period 1897-1902, 

 are recorded and commented upon by Prof. Barnard in the 

 current number of the Astrophysical Journal. 



The observations are recorded in extenso, and contain full 

 details of the various phenomena attending the displays. 

 Special notice is made of several interesting features, amongst 

 them being the bank of apparent cloud which has a dark, smoky 

 appearance and generally fills the space on the under side of the 

 auroral arch. This cloud generally gives the appearance of 

 being densely opaque, but that this is not the case is shown by 

 the fact that the observations record the bright appearance of 

 Vega as seen through the apparent cloud. The " pulsating 

 clouds," which are generally 5 to 10° in diameter, are recorded 

 as " fading out and quickly brightening again, as if someone 

 were capriciously turning on and off their light." Another 

 striking feature of the subject, which Prof. Barnard believes to 

 be of importance, is the greatly varying altitudes of the summits 

 of different aurorce, and these are carefully noted in the observ- 

 ations. The positions of the summits of various aurorce are 

 generally recorded as being 20 to 25' east of north. A singular 

 appearance — unique in Prof. Barnard's observations of these 

 phenomena — was that of a quarter of an auroral arch on 

 February 15, 1899, no other signs of auroral display being visible 

 at the time. 



The Yerkes observations of the grand aurora of September 10, 

 189S, which was accompanied by decided magnetic effects, 

 describe it as the grandest display observed throughout the 

 whole period, and state that the light in the north was so 

 intense, at times, as to cast a distinct shadow. 



As Prof. Barnard remarks, these observations, which cover a 

 period of sun spot minimum, will doubtless be important in their 

 bearing on the connection between sun-spots and aurorse. 



Cooperation in Observing Stellar Radial Velocities. 

 — Prof. E. B. Frost, having been struck by the fact that it is 

 not possible to find, amongst published observations, a dozen 

 stars the radial velocities of which have been determined at 

 more than three different observatories, has sent a circular letter 

 to the recognised workers in this field of astronomical physics 

 asking them to join in a cooperative scheme for observing the 

 radial velocities of the stars given in a mutually selected list. 



All of the observers to whom the letter was addressed, seven 

 in number, have agreed to the general scheme, and a primary 

 list of about ten stars has been decided upon. Their programme, 

 for the present, includes the making of three determinations of 

 the radial velocity of each star in the list, per annum, by each 

 observer (Astrophysical Journal, October.) 



The Markings on Venus. — Prof. Percival Lowell, of 

 Boston, has written to the Astronomische Nackrichten, No. 3S23, 

 suggesting that the spoke-like markings of the planet Venus are 

 not really present on the surface of the planet, but that their 

 appearance is due to an optical effect produced by the eye 

 wandering from the dark indentations which are seen along the 

 terminator, and the smaller spots and streaks, to the centre of 

 the disc. To test this theory, Prof. Lowell has observed a large 

 number of artificial discs, marked without his knowledge, and 



NO. 1725, VOL. 67] 



set up at a distance so as to be, as nearly as possible, under the 

 same observing conditions as the planet. 



These experiments tend to prove his theory, but are not 

 sufficiently decisive to place the non-objective existence of these 

 peculiar markings beyond doubt ; therefore Pro f . Lowell, for the 

 present, only enters a caveat against the acceptation, as a fact, 

 of their real existence. 



THE N ERNST LAMP. 



""THE Nernst lamp can now be said to be well upon its way 

 from the experimental to the commercial stage. It has 

 appeared strange to many people that it has taken such a long 

 time before lamps could actually be bought for use, but a critical 

 examination of the lamps now to be had causes one to wonder, 

 not that its development has taken a long time, but that it has 

 been possible to practically develop it at all. Of all artificial 

 methods of illumination it is the most complicated, and its 

 various auxiliary parts are in themselves inventions requiring for 

 their inception no ordinary genius and perseverance. The Nernst 

 lamps now to be had in England are made by the Allgemeine 

 Elektricitats Gesellschaft of Berlin. The only other manu- 

 facturer of Nernst lamps is the Nernst Lamp Company of the 

 United States, which has acquired the rights for that country. 

 The demands of the rest of the world are being supplied by the 

 A. E.G., the agent of whom for the British Colonies, Asia, 

 Africa and South America is the Nernst Electric Light, 

 Limited, of London, which, in the form of an attractive 



Fig. i. Fig. 2. 



pamphlet, has just issued a description of the various lamps it 

 is prepared to sell. 



The lamps are of two types and are rated by current, not, as 

 is usual with incandescent lamps, by candle-power, viz. 0'25, 

 0"5 and 1 x> ampere lamps. The watts consumed per candle- 

 power are about 1 '8. 



The larger lamp used for all high candle-powers, i.e. 50 candle- 

 power and upwards, consists of three parts, the carrier, the 

 lamp body and the globe. The current is led into the lamp 

 body by insulated plug contacts, on the withdrawal of whichthe 

 lamp is rendered entirely dead and can be handled with safaty. 

 The lamp body contains the magnetic cutout for interrupting the 

 current through the heater, after the glower has lighted up, also 

 the series resistance. The contacts for the replacement piece 

 are also carried by the lamp body. This is shown in Fig. 1, and 

 consists of a round piece of porcelain on which are fixed the 

 heater and glower. The general connections of the lamp, as also 

 the functions of its several essential parts, can be seen by refeience 

 to Fig. 2. On first switching on current to the lamp, the circuit 

 is closed through the armature and contact c of the cutout M, and 

 through the heater H. The heater is a marvel of ingenuity. It 

 consists of an exceedingly fine platinum wire wound on a rod of 

 porcelain, the rod being in the form of a spiral in the axis of 

 which the glower G is placed. The method of manufacture 

 adopted is to wind the straight rod with the wire, then to cover 



