532 



NATURE 



[August 30, 191 7 



OVR ASTRONOMICAL COLUMN. 



Comet 1916b (Wolf). — The following is a continua- 

 tion of Messrs. Crawfurd and Alter's ephemeris of this 

 comet, for Greenwich midnight : — 



1917 R.A. Dec]. Log A Bright- 



h. m. s. , , „ ness 



Aug. 31 23 40 22 +12 24 23 9-999^ 



Sept. 2 40 22 II 34 5 00020 229 



4 40 18 10 43 12 00045 



6 40 12 9 51 55 00074 2- 17 



8 40 4 9 o 25 00108 



10 39 53 8 8 54 0014b 205 



12 39 42 7 17 34 00188 



14 39 29 6 26.35 00234 1-91 



16 39 16 5 36 9 00284 



18 39 4 4 46 27 00338 177 



20 38 52 3 57 38 00396 



22 38 41 39 52 00457 1-63 



24 38 31 2 23 17 00522 



26 38 24 I 38 I 00590 1-49 



28 38 18 o 54 II 00661 



30 38 15 on 50 00735 1-35 



The unit of brightness is that on April 21, 1917. 

 The comet will be at opposition on September 17. 



Radial Velocities of Spiral Nebula:. — In view of 

 the faintness of spiral nebulae, and the small dispersion 

 necessarily employed in photographing their spectra, 

 some doubt may have been felt as to the reality of the 

 extraordinarily high radial velocities which have been 

 derived for these objects. A recent statement by Dr. 

 V. M. Slipher, however, appears to place the main 

 results beyond question (the Observatory, August), The 

 average velocity which he has found for thirty spirals 

 is 570 km. per second, and he points out that this is 

 more than twenty-five times the velocity of an average 

 star. Thus, although the spectrograph employed for 

 nebulae at the Lowell Observatory has a linear scale 

 only about one-fifteenth that of a powerful three- or 

 four-prism spectrograph, it is at no disadvantage as 

 regards the relative accuracy of the results pl^tainable 

 in the two cases, when similar precautions have been 

 taken. Further confidence is given by the agreement 

 in the results obtained for the Great Andromeda nebula 

 at four different observatories, namely, velocities of 

 approach of 300, 304, 300-400, and 329 km. per second. 

 These compare very favourably with the values which 

 have been found for stellar velocities by different 

 observers, those for Canopus, for example, ranging 

 from 185 to 210 km. per second. 



The History of Orbit Deduction. — In an address 

 on "The Derivation of Orbits: Theory and Practice," 

 delivered to the American Mathematical and Astro- 

 nomical Societies, and published in Science of June 8, 

 Prof. A. O. Leuschner deals in an interesting and 

 illuminative manner with the history of orbit deduc- 

 tion from Newton downwards. Prof. Leuschner him- 

 self introduced some very useful modifications a few- 

 years ago, and his method is now generally acknow- 

 ledged to be the most rapid and convenient for obtain- 

 ing preliminary orbits of newly discovered planets or 

 comets. It is based on that of Laplace, using three 

 observed right ascensions and declinations, and, their 

 first and second differences. This method fell into dis- 

 credit owing to some over-hasty strictures of Lagrange ; 

 it had the undoubted disadvantage that the first and 

 third observed positions were not exactly satisfied by 

 the resulting orbit. Harzer showed how differential 

 corrections might be applied, and Leuschner intro- 

 duced further improvements, which are best sum- 

 marised in his own words. "Criteria have been intro- 

 duced . . . regarding the eccentricity. Provision has 

 been made for passing- from parabola to ellipse without 

 repeating the solution. Numerical criteria have been 

 set up to distinguish the physical from the mathe- 



NO. 2496, VOL. 99] 



matical solutions. .\ method has been provided for 

 eliminating the parallax. The various approximations 

 for the distances are avoided ; these are taken from a 

 table ; the accuracy attainable in each case can be 

 ascertained, and the range of solution determined." 

 These claims are well justified in the numerous orbits 

 that have been published by Prof. I^euschner and his 

 students. The case of planet MT (Albert) was par- 

 ticularly striking. Dr. Haynes obtained an orbit from 

 three observations, at very short intervals, by the aid 

 of which several other places were found on later 

 plates ; they were so faint that an approximate know- 

 ledge of the position was required before they were l 

 detected. 



PROGRESS OF APPLIED CHEMISTRY. 



THE annual general meeting of the Society of 

 Chemical Industry was held in Birmingham on 

 July 18-20. At the opening meeting the chair was 

 taken by the Lord Mayor of Birmingham, Aid. A. D. 

 Brooks, who, in an address, said the society had two 

 chief objects at present : first, to assist in the prosecu- 

 tion of the war, and, secondly, to do its best to 

 help the country after the war. The war w-as being 

 carried on largely by scientific methods, and the 

 chemist was devoting his attention chiefly to destroy- 

 ing human life, whereas formerly his efforts had been 

 directed to the elimination of things dangerous to life. 

 Before the war Englishmen had allowed important 

 improvements to pass into other hands, but they must 

 see to it that this did not happen again. Suspended 

 industries must be rebuilt, and all conducted on sound 

 economical lines, using to the full all scientific and 

 technical help. Alluding to Birmingham industries, 

 the Lord Mayor emphasised the need for recovery of 

 waste products and consetving mineral resources. 



Dr. Carpenter replied suitably, and proceeded to read 

 his presidential address. He indicated the basis of 

 modern industry in the sciences of mechanics and 

 chemistry, and insisted on' the absolute necessity for 

 the engineer and the chemist to "get into double 

 harness as quickly as possible " and work sympathetic- 

 ally together for the progress of the chemical industry. 

 Each paper given during the congress might be cited 

 as an exemplar of the president's remarks. Each was 

 a record of an effort or ettbrts of the chemist to co- 

 operate with the engineer, and in this way to further 

 the interests of some industry. For example, Messrs. 

 Hancock and King, in their paper on "The Texture of 

 Fireclays," described methods of comparing the un- 

 fired fireclay with the finished material, and the paper 

 by Mr. Henry Watkin on chemical porcelain was a 

 record of many persistent attempts to convert the 

 various clays found in different parts of the world into 

 the finished materials satisfying many practical re- 

 quirements. The latest and, according to Mr. Wat- 

 kin, a completely successful attempt has been made 

 in this country since the outbreak of war to produce in 

 England a chemical procelain similar to that which 

 was monopolised by Germany before the war. 



Prof. Boswell instanced the fact that the war had 

 greatly increased the output of glass and all kinds of 

 metals and alloys, and he gave a record of work 

 directed to the furnishing of British sand for the glass 

 and metallurgical industries. Here the preliminary 

 analytical work, which is of fundamental importance, 

 forms a basis for all the far-reaching consequences 

 which will follow for these industries in this country. 

 No finer example could be given than that of the 

 modern gas industry illustrating the joint and success- 

 ful co-operation of the chemist and the engineer, and 

 the paper given by Mr. E. W. Smith, emphasising the 

 merits of gas as an industrial fuel as against coal, 

 etc., and that by Mr. C M. Walter, exemplifying the 



