September i, 1923] 



NATURE 



31 



Dr. George H. Pethybridge, until recently head 

 of the Seeds and Plant Disease Division of the 

 Department of Agriculture and Technical Instruc- 

 tion for Ireland, has been appointed mycologist to 

 the Ministry of Agriculture and Fisheries for Eng- 

 land. 



Dr. C. E. K. Mees has described, in the Journal 

 of the Franklin Institute for August, the way in which 

 the Eastman Kodak Company has sought to overcome 

 the chief difficulties that prevent " motion photo- 

 graphy " from being available for general purposes, 

 reducing the cost and facilitating the development, 

 etc., of the film. The " Cine Kodak " weighs about 

 8 pounds and takes loo feet of film, which is equivalent, 

 with its smaller pictures, to 250 feet of film of the 

 standard size. The projector is driven by a motor 

 so that it is automatic, and has a capacity for 400 feet 

 of film, which] requires 16 minutes to show on the 

 screen. A large saving is effected in the cost of the 

 film by its smaller size, and a further economy is 

 gained in the majority of cases where only one film 

 of the subject is required, by treating the exposed 

 film by a reversing process, instead of making the 



positive by printing it on a second film. But " this 

 is quite a complicated process and requires very 

 special and complicated equipment " to avoid the 

 appearance of graininess on the screen, so the Company 

 undertakes this work itself. By these means the 

 fifteen cents per second of picture as shown on the 

 screen, which is about the cost of a standard film, is 

 reduced to two and a half cents per second ; and as 

 7 or 8 seconds is a sufficient duration of exposure for 

 a single scene (such as a waterfall or a game), the cost 

 for one subject is about 20 cents, and this compares 

 favourably with the cost of making a negative and 

 one print in the ordinary way. The film base is 

 made from cellulose acetate, so that the risk from 

 fire that the ordinary film of cellulose nitrate suffers 

 from is practically done away with. 



A NEW edition of his work on " The Endocrine 

 Organs " is being prepared by Sir E. Sharpey 

 Schafer for publication by Messrs. Longmans and 

 Co. Part I, dealing with the thyroid, parathyroids 

 and suprarenals, will appear this autumn, and 

 Part 2, embracing the rest of the subject and com- 

 pleting the work, next year. 



Our Astronomical Column. 



The Total Solar Eclipse of September 10. — This 

 eclipse is total in south-west California and the ad- 

 jacent islands ; also in Mexico. There is no official 

 expedition from the British Isles, but many of the 

 great American Observatories are sending parties to 

 observe it. Popular Astronomy for June- July con- 

 tains an outline of their programmes. The Yerkes, 

 Washburn, and Goodsell Observatories are occupying 

 Catalina Island. The Washburn party will measure 

 the brightness of the corona by the photo-electric cell ; 

 the Goodsell party will photograph the corona and star- 

 field with an 8-inch lens, and the flash spectrum with 

 a grating. 



Mt. Wilson and Leander McCormick Observatories 

 will occupy two stations ; at Point Loma the corona 

 and star-field will be photographed, also the spectra of 

 corona and chromosphere ; the interferometer will be 

 used to determine the wave-length of the green coronal 

 line and the rotation period of the corona. Their 

 other station is at Lakeside, near the northern limit 

 of totality, where the flash spectrum will be photo- 

 graphed with concave gratings. 



The Lick Observatory, and the Students' Observa- 

 tory of the University of California, will work together 

 at Ensenada. The polarisation of the coronal light 

 will be measured, and many other researches made. 



The Sproul Observatory is occupying Cuencame, 

 Mexico, and will photograph the corona both on a 

 large and a small scale ; also the flash spectrum. The 

 interferometer will be used to study the rotation of 

 the corona. 



The University of Toronto will study the spectrum 

 and polarisation of the corona. 



The Steward Observatory (University of Arizona) 

 and the Mexican National Observatory will also 

 occupy stations in Mexico. 



The Lick Observatory will not repeat the Einstein 

 investigation, believing that the question was suffi- 

 ciently settled at the eclipses of 1919 and" 1922. The 

 Goodsell, Mt. Wilson, and Sproul Observatories will 

 take star photographs for this purpose, though the 



star-field is a poor one — less suitable than those of 

 1919, 1922. Signor Emanuelli, of the Vatican Obser- 

 vatory, gives a list and diagram of the stars in the 

 region in Astv. Nach. There are three stars (magni- 

 tudes 8-8, 8-5, 8-o) with Einstein displacement exceed- 

 ing i" ; they are likely to be hidden in the corona : 

 six stars with displacements between i-o" and o-6" 

 (magnitudes 8 to 9) ; thirteen stars between o-6" 

 and 0-4" ; fifty-eight stars between 0-4" and 0-2". 

 Some of these last are fairly bright, one being 

 (T Leonis. 



Internal Motion in the Spiral Nebula Messier 

 33. — Mr. A. van Maanen contributes another of his 

 important papers on internal motion in the spiral 

 nebulae to the Astrophys. Journ. for June.' The 

 measures were made on pairs of plates taken with the 

 60-inch reflector, the time interval being 1 2 years ; 

 .24 comparison stars and 400 points presumably belong- 

 ing to the nebula were measured. One of the latter 

 shows an annual displacement of 0-136", so that its 

 connexion with the nebula is disproved. The 

 remaining points when plotted show consistent 

 motions outwards along the arms of the spiral. The 

 mean annual motion of the nebula as a whole, rela- 

 tively to the comparison stars, is +0-003" ^^ R.A., 

 -0-004" in decl. The motions of the nebular points, 

 in addition to their outward movements, indicate 

 rotation in periods varying from 60,000 years for the 

 inner portions to 240,000 years for the outer ones. 

 The mean component of velocity along the nebular 

 stream is + 0-020" ; it increases slightly as the distance 

 from the centre increases. 



Mr. van Maanen gives in full the reasoning which 

 leads to the conclusion that these displacements are 

 real. Taken in conjunction with the radial velocities 

 measured, they indicate a parallax of the nebula of 

 the order of 0-0005", or a distance of 6000 light-years. 

 The diameters of the spirals are many light-years (in 

 some cases hundreds of light-years), but they are much 

 smaller objects than the Galaxy. 



NO. 2809, VOL. I I 2] 



