482 



NATURE 



[December 9, 1920 



to-day. Mr. Atkinson looked forward to further pro- , 

 f^ress in the gas turbine, and hinted that some process 

 of current production avoiding the limits imposed by 

 the second law of thermodynamics might be found, 

 and that perhaps an electrical method of unlocking i 

 the stores of energy in the atom might ultimately be 1 

 discovered. After a few words on the history of 

 electric supply, transmission of power, and cable i 

 manufacture, Mr. Atkinson passed on to a review of ] 

 telegraph and telephone progress. Both submarine i 

 and land line telegraphy had reached a high degree ] 

 of advancement when the institution was founded, | 

 but the telephone did not exist, and such ideas as 

 there were on the possibility of communication with- ; 

 out wires were in the direction of earth conduction. I 

 Recent developments included applications of the 



wonderful thermionic amplifier to cable telegraphy 

 as well as to line telegraphy and wireless, .\mong 

 matters requiring further research were the develop- 

 ment of more exact methods of estimating the quality 

 of transmitted speech and multiplex and superposed 

 telephony. 



Messrs. \V. Heffer and Sons, Ltd., Cambridge, 

 have just issued a catalogue (No. 194) of publishers' 

 remaindei's which should be seen by those on the look- 

 out for standard books in a new condition as Christ- 

 mas or New Year presents. Many of the volume* 

 offered for sale deal with scientific subjects, but most 

 are of general interest. All are listed at prices far 

 below those at which they were published. The 

 catalogue is obtainable upon application. 



Our Astronomical Column. 



The December Meteors. — These ineteors are due 

 to reappear on the nights of December 10-13, and 

 with suitable weather ought to be well observed this 

 year, as there will be no interference from moon- 

 light. The maximum will probably occur on 

 December 12, when the radiant will be at 112° + 33° 

 near aGfeminorum. The point of radiation ap- 

 parently moves eastward at the rate of 1° daily. The 

 meteors are moderately swift, sometimes slow, but 

 their individual aspects depend in a measure upon 

 their relative positions with respect to the observer 

 and the radiant. In the early hours of the evening 

 the flights are longer than in the later part of the 

 night, the radiant being higher in the sky in the 

 small hours of the morning. 



Minor Planets. — Ceres will be in opposition on 

 Christmas Day in high north declination, its magni- 

 tude being 72. The following approximate ephemeris 

 for Greenwich midnight is from Marseilles Circular 

 No. 412 : 



R.A. N. Decl. R.A. N. Decl. 



h. m. s. o / h. m. s. , , 



Dec. 3 6 37 48 25 27 Dec. 18 6 24 30 26 41 



8 6 33 54 25 52 23 6 19 24 27 5 



13 6 29 24 26 17 28 6 14 6 27 27 



Log r, log A December 3, 0424, 0-240; Decem- 

 ber 23, 0-421, 0-219. 



The planet is close to € Geminorum at the beginning 

 of December. 



AsU. Nach. Circular No. 46 reports the discovery 

 of a very interesting planet which has been provi- 

 sionally named HZ. It was found photographically 

 by Dr. W. Baade at Bergedorf on October 31, and 

 observed again on November 2 and 12, its magni- 

 tude being about 13. Dr. G. Stracke has computed 

 the following elements : 



Epoch 1920 October 31-5 G.M.T. 



M = 348° 33' 35-4 

 <» = 57 38 40"2 

 f7,= 21 22 26-8 



/ = 41 28 58-6 

 ^=37 31 08 



;x = 320-085" 



log « = o'696494 



log f = o-2iSj 



T=i92i March 9'2 

 Equinox 19200 



It will be observed that the value of the mean motion 

 would make it a member of the Trojan group, but 

 the very large inclination and eccentricity (which are 

 cometary rather than planetary) would prevent any 

 close adherence to the equilateral configuration with 



NO. 2667, VOL. 106] 



the sun and Jupiter, which is the characteristic of 

 that group. 



Ephemeris for Greenwich Midnight. 



R.A. N. Decl. 



» h. m. s. . , 



December 6 ... o 8 16 18 27 



10 ... o 7 24 19 18 



The perihelion and aphelion distances are 1-944 ■'"'' 

 7-998 respectively. 



Photogr.whic Parallax Deter.mis.4T10N!> .\i 

 Allegheny. — Vols. iv. and v. of the Publications of 

 this observatory, of which Prof. F. Schlesinger is 

 director, contain parallaxes of nearly three hundred 

 stars, the average probable error being given as 

 0-008". A few of the larger parallaxes are recorded 

 below, with notes on previous determinations. An 

 asterisk denotes a spectroscopic parallax : 



Star 



Parallix 



Some previous determinations 



T Cygni ... o'ojS 0-125, o'029, o'oo6, ©•023 



I Pegasi ... 0-067 0063,0120 



/x „ ... 0043 



j3 Virginis ... 0096 o'l 10, 0100*, 0096 



42 Coronae ... 0064 0119,0058 



f Herculis ... 0-114 0-172, o-ioi, 0-146, 00S6, 0066* 



H „ ... 0-104 0122,0-126,0-093,0-051,0-096* 



85 Pegasi ... 0084 0-054,0096,0-084,0-101,0090* 



fOS 547 (mean) 0103 0-134, oo95> 0-120* 



\Furuhjelm star • 0099 0-112 



X Orionis ... 0-096 



8 Canum Ven. 0109 0089, 0-084, 0105* 



I Bootis ... 0-147 0-225, 0-151* 



I) Cassiopeiae... 0-173 o-l88, 0-182, 0178*, 0180 



61 Cygni (mean) 0-285 0-270,0-272,0-322,0-301 



Castor (mean) 0-070 0-053 



il'his star has the same P.M. as 02 547, being 5 J' distant. 



The great advance in the accuracy of photographic 

 parallaxes in recent years is very satisfactory. It 

 may be ascribed to the many additional precautions 

 now taken, notably the equalisation of magnitudes 

 by rotating sector or otherwise, and confining the 

 photographs to the neighbour-hood of the meridian to 

 minimise the effect of atmospheric dispersion. 



Vol. vi.. No. 2, of the .Allegheny Publications con- 

 tains a paper by Mr. C. J. Hudson on the amount 

 of error arising from this dispersion. The effect on 

 pairs of plates taken at considerable hour-anjjles east 

 and west is 0-021". It should be quite negligible on 

 the parallax plates. 



