March io, 192 i] 



NATURE 



55 



the pressure at any chosen position. The search-tube 

 has already given excellent results in the hands of 

 Prof. Stodola, but the method of analysis adopted in 

 the present series is believed to be new. The results 

 are exhibited in the form of curves, and the following 

 are some of the author's deductions : — ^The purely 

 convergent form of nozzle operates very much in 

 accordance with theoretical ideas ; it has a 

 smooth expansion line in agreement with its well- 

 rounded form, and a maximum range approxi- 

 mately in line with the theoretical critical drop. The 

 convergent-parallel type scarcely acts in keeping with 

 preconceived ideas ; this form of nozzle should be 

 considered one of extended convergence only. In both 

 the above types theory demands a maximum range 

 limited to a pressure ratio of 055 ; the actual ranges 

 have only rough agreement with this figure. The con- 

 vergent-divergent type has one over-all range in which 

 the fall of pressure is continuous, but the throat pres- 

 sure seems always to be below the theoretical. Sharp- 

 entranced nozzles were also experimented with. 



With reference to the letter published in Nature 

 of February 3 discussing coloured thinking and 

 thought-forms, Mr. G. Stridsberg, of Stockholm, 

 wishes to direct attention to a communication by 

 Prof. H. Mygind, of Copenhagen, which appeared in 

 the Danish review Tilskueren for 1884 (pp. 361-78) 

 entitled "Om Erinring og Fantasi aforistiske Be- 

 tragtninger" ("Aphorisms on Memory and Imagina- 

 tion "). 



A LENGTHY Catalogue (No. 197) of scientific books 

 and publications of learned societies, consisting of 

 upwards of 2000 items, has reached us from Messrs. 

 W. Heffer and Sons, Ltd., Cambridge. As will be seen 

 by the following table of contents, it contains titles of 

 works in most of the sciences. It should therefore 

 appeal to many readers of Nature, who can obtain 

 the catalogue upon request. The list is classified as 

 follows : — Mathematics, Physics, Astronomy, and 

 Early Philosophy; Engineering; Agriculture, Hus- 

 bandry, and Farriery; Anthropology and Ethnology; 

 Botany; Chemistry, Chemical Technology, and 

 Metallurgy; Geology, Mineralogy, and Palaeonto- 

 logy; Zoology and Biology; Physiology, Anatomy, 

 and Medicine ; Portraits of Men of Science ; Psycho- 

 logy and Psycho-Analysis ; and Addenda. 



A CATAL9GUE (No. 410) of antiquarian and biblio- 

 graphic interest has just been issued by Mr. F. 

 Edwards, 83 High Street, Marylebone, W.i. It 

 gives particulars of some 300 books, maps, plans, 

 and engravings relating to London and its vicinity, 

 and will be sent free upon application. 



The Smithsonian Institution issues a classified list 

 of its publications available for distribution to scien- 

 tific workers either gratis or at the prices indicated. 

 Publications of the United States National Museum 

 and of the Bureau of American Ethnology are not 

 included. The list before us, which is Publication 

 2585, is brought down to August 21, 1920. 



Our Astronomical Column. 



Large Meteors on March i and 2. — Mr. W. F. 

 Denning, of Bristol, writes : — " On the evening of 

 Tuesday, March i, two large meteors were observed, 

 and on the following night three others were recorded. 

 The most brilliant of them all appeared on March 2, 

 at 10 p.m. It was seen at Bristol, at Dunton Green, 

 Kent, at Holt, Norfolk, and at other places. It was 

 a very fine object, and gave a flash which lit up the 

 sky. Its radiant point was a few degrees east of 

 8 Leonis, and the path of the meteor was over the 

 English Channel approximately from Dieppe, France, 

 towards the Isle of Wight, but reaching only about 

 half that distance. Observations are still coming to 

 hand, and the r^al path will be calculated from them. 

 It has been several times pointed out that the first 

 few nights of March are specially distinguished by 

 apparitions of bright meteors, although no periodic 

 shower is known to occur on those dates. There 

 appear, however, to be several fairly active displays 

 in progress, and from the evidence obtained this year 

 we may be enabled to determine their radiant points 

 accurately." 



Pons-Winnecke's Comet. — This comet has not yet 

 been detected — which is a matter for surprise. In 

 19 1 5 it was photographed five months before peri- 

 helion, and it should now be within the reach of 

 moderate instruments, especially as it is very favour- 

 ably placed in the morning sky. The following 

 elements are likely to be near the truth :— w 174°, 

 SI 96°, i 19-5°, q loi, log a 0509, e 0687. The most 

 uncertain element is the date of perihelion. The fol- 

 lowing ephemerides for Greenwich midnight are based 

 on the assumed dates: — 1921 June 13-5 and June 21-5. 

 The uncertainty is considerably greater than eight 

 NO. 2680, VOL. 107] 



days, so the search should extend beyond the limits 

 of the ephemerides ; these, however, should define the 

 line on which it lies with tolerable precision : 



T=i92i June 13-5. 



R.A. N. Decl. log r lop A 



h. m. s. c , 



March 7 14 47 44 25 58 0-2126 99291 



15 15 I 16 28 42 01932 98785 



23 15 15 48 31 39 0-1729 9-8269 



31 IS 30 23 34 51 0-1519 9-7731 



T=ig2i June 21-5. 



March 7 14 13 18 2931 0-2317 9.9453 



15 14 2 1 12 3235 0-2126 98984 



23 14 27 8 35 58 0-1932 9-8522 



31 143223 3926 0-1729 9-8064 



The search should be carried on assiduously up to 

 March 20, after which the moon will interfere. 



Two Nebula with Unparalleled Velocities. — 

 Prof. V. M. Slipher announces that the spiral nebulae 

 N.G.C. 584 (R.A. ih. 27-3m., declination -7° 16') and 

 N.G.C. 936 (R.A. 2h. 23m., declination - 1° 33') have 

 extremely high recessional velocities, which are 1800 

 and 1300 km. /sec respectively. There is a decided 

 preponderance of recessional motion indicated for the 

 spiral nebulae. 



Prof. Eddington (" Report on the Relativity Theory 

 of Gravitation," p. 89) suggested that these high velo- 

 cities may not be real, but a result of the curvature 

 of space in Einstein's system, according to which 

 very distant objects would have their spectral lines 

 shifted towards the red. 



