June 17, 1897] 



NA TURE 



63 



OUR ASTRONOMICAL COLUMN. 

 New Southern Variable Stars. — During the past few 

 years Prof. Kapteyn has been obtaining the negatives for the 

 Cape Photographic Durchinusierung, but, owing to great pres- 

 sure of work at the observatory, a minute examination of the 

 plates could only until quite recently be made. As a result of 

 such a search several new variable stars have been discovered ; 

 and if this examination had been commenced earlier, there is 

 little doubt that five other variables discovered independently 

 would have been credited to the Cape Observatory. The list of 

 new variables now published by Dr. Gill {Asir. Nachr., 3426) 

 includes four well-marked variables, their positions for 1875 

 and magnitudes being given in the following table. The range 

 of magnitude, as given by the plates examined, is shown in the 

 third column. 



'•(>875o) «(i875-o) Range of 



h. m. s. ^ , magnitude. 



4 50 56 -21 24-9 9-25— 98 



8 41 3 -50 6-4 96 — 100 



f 8-8 — 8-9 



9 28 41 -36 3-8-87 - 9-6 



Nov. '95 and Feb. '96 

 Jan. -April '96 

 May 14, 28, '90 

 Feb. 22, 24, and 

 \ March 7, '96 



12 25s -44 437 8-95-975 March '96 

 The .same communication also refers to stars of the 9th 

 magnitude, or brighter, which are contained in the Cordova 

 DunhniHsteiung, but are missing, or barely visible, in the Cape 

 plates. The variability of five other stars has in this way been 

 established. 



The 1897 Maximum of Mira Ceti — Prof. J. A. C. 

 Oudemans comnmnicates a paper by Dr. Nyland, of Utrecht, 

 who carefully observed the variable Mira Ceti from August 5, 

 1896, to March 10, 1897, although as he states the weather re- 

 stricted his observations to a great extent. On the whole, how- 

 ever, the observations were fairly distributed over this period, 

 with the result that a very good curve could be drawn through 

 the points when laid out on millimetre paper. The curve which 

 is included in the communication {Aslr. Nachr., No. 3426) in- 

 dicates that on September 2, 1896, this star was at its minimum 

 brightne.s.s, 8*50 mag.; while on January 11, 1897, it had risen to 

 a maximum, namely 370 mag. The.se magnitudes would corre- 

 spond to 88 and 3*5 on the scales of Schonfeld and Argelander. 

 This further stated that the magnitude at this period of 

 maximum was very small, in fact among the fourteen observed 

 maxima in the years 1840 1859 only one was observed (1847 

 November 16) that was dimmer than that of 1897. 



Comet Denning 1894 I.— Prof Schulhof compares (^////^//« 

 Astronomique, Tome xiv. p. 168) the observed places of this 

 comet with those given by the ephemerides. Using his second 

 system of elliptic elements {.Astr. Nachr., •'iHo. 3231) he finds 

 that the corrections to the ephemerides is very considerable for 

 the five last observations made at Nice. He has then employed 

 his third system of elements [Astr. Nachr., No. 3236) for the 

 representation of these observations, but still this does not 

 reduce the difierences very considerably. Prof. Schulhof finally 

 formed his five normal places and represented them by 

 the fourth system of elements {Astr, Nachr., No. 3276.) In this 

 way he formed a table giving the corrections to be applied to 

 the provisional ephemerides and the deduced positions. The 

 elements he finally uses are, as he says, probably a little nearer 

 the truth than those of M. Lamp {Astr. Nachr., 3278). With 

 regard to the relation between Brorsen's Comet and that of the 

 one in question, M. Lamp. showed that the two comets on January 

 24, 1 88 1, pas.sed nearly simultaneously the same point in space 

 where their orbits coincided, namely, 7=284' 27', b 6= - x°46', 

 ^=5-1827, and both he and Mr. Hind have considered this 

 comet of Denning's as a fragment of that of Brorsen. Prof. 

 Schulhof does not, however, seem to think this hypothesis is 

 confirrned. The elements of the two comets, he states, are too 

 dissimilar to .allow of such an a.ssumption, -n and Q, differing by 

 15^, and the inclination by nearly 24°. The two velocities at 

 the period indicated above differed by as much as three kilo- 

 metres per second, and such an increase in velocity, he states, is 

 probably too large to be cau.sed by the shock of an explosion. 



OB.SERVATIONS OK Mars.— The current number of the 

 Bulletin de la Sociite Astronomu/tie de France (June) is devoted 

 mainly to observations of Mars made by several well-known 

 observers. Mr. Percival Lowell records some curious observa- 

 tions of the Sea of Sablier, or Syrtis Major. This marking 



NO. 1442, VOL. 56] 



has always been looked upon as an expanse of water or a sea ; 

 but Mr. Lowell's recent observations seem to corroborate those 

 of Prof W. H. Pickering, who examined this spot with a 

 polariscope, and could detect no sign of polarisation. He says 

 that the Syrtis Major is neither an ocean, nor a sea, nor any- 

 thing analogous, but something very different, namely, a large 

 expanse of vegetation. The changes observed in this marking 

 in 1896 seem, at any rate, to suggest such an explanation as 

 offered by Mr. Lowell. 



The other observations included are : — Mr. R. Patxot Tubert's, 

 made at the Observatory of Sant Feliu de Guixols" Gerona 

 (Spain) ; Mr. Jose Comas Sola's, made at Barcelona ; Mr. V. 

 Cerulli's, made at Teramo (Italy) ; Mr. A.-A. VVonaszer's, 

 made at Kis-Kartal ; and MM. Flammarion's and Antoniadi's, 

 made at the Observatory of Juvisy. M. Antoniadi gives also 

 a map of the whole surface as seen by him during the oppo- 

 sition of 1896, and a comparison of this with charts made at 

 other previous oppositions is of great interest. The observations 

 made during 1896 indicate, on the whole, that great changes 

 take place on the planet's surface. The question of vegetation 

 and a small water supply seems, perhaps, to account for the ob- 

 served facts more than any other hypothesis yet advanced, and 

 this explanation is in conformity with rapid seasonal changes 

 which have recently become so apparent. 



SIGNALLING THROUGH SPACE WITHOUT 



WIRES} 

 TN 1884 messages sent through insulated wires buried in iron 

 pipes in the streets of London were read upon telephone 

 circuits erected on poles above the housetops, 80 feet away. 

 Ordinary telegraph circuits were found in 1885 to produce dis- 

 turbances 2000 feet away. Distinct speech by telephone was 

 carried on through one quarter of a mile, a distance that was 

 increased to one and a quarter mile at a later date. Careful 

 experiments were made in 1886 and 1887 to prove that these 

 effects were due to pure electro-magnetic waves, and were entirely 

 free from any earth-conduction. In 1892 distinct messages were 

 sent acro.ss a portion of the Bristol Channel between Penarth 

 and Flat Holm, a distance of t,'}, miles. 



Early in 1895 the cable between Oban and the Isle of Mull 

 broke down, and as no ship was available for repairing 

 and restoring it, communication was established by utilising 

 parallel wires on each side of the Channel and transmitting 

 signals across this space by these electromagnetic waves. 



In the electro-magnetic system two parallel circuits are estab- 

 lished, one on each side of a channel or bank of a river, each 

 circuit becoming successively the primary and secondary of an 

 induction system, according to the direction in which the signals 

 are being sent. Strong alternating or vibrating currents of 

 eleCtricityare transmitted in the first circuit so as to form signals, 

 letters and words in Morse characters. The effects of the rise 

 and fall of these currents are transmitted as electro-magnetic 

 waves through the intervening space, and if the secondary 

 circuit is so situated as to be washed by these ethereal waves, 

 their energy is transformed into secondary currents in the second 

 circuit which can be made to affect a telephone, and thus to 

 reproduce the signals. Of course their intensity is much reduced, 

 but still their presence has been detected though five miles of 

 clear space have separated the two circuits. 



Such effects have been known .scientifically in the laboratory 

 since the days of Faraday and of Henry, but it is only within the 

 last few years that it has been possible to utilise them practically 

 through considerable distances. This has been rendered possible 

 through the introduction of the telephone. 



In July last Mr. Marconi brought to England a new plan. 

 My plan is based entirely on utilising electro-magnetic waves of 

 very low frequency. It depends essentially on the rise and 

 fall of currents in the primary wire. Mr. Marconi utilises 

 electric or Hertzian waves of very high frequency, and they 

 depend ui^on the rise and fall of electric force in a sphere or 

 spheres. He has invented a new relay which, for sensitiveness 

 and delicacy, exceeds all known electrical apparatus. 



The peculiarity of Mr. Marconi's system is that, apart from 

 the ordinary connecting wires of the apparatus, conductors of very 

 moderate length only are needed, and even these can be dis- 

 pensed with if reflectors are used. 



1 Abstract of a di.-icourse delivered before the Royal Institution. June 4, 

 by W. H. Pretce, C.B., F.R.S. 



