October 14, 1920] 



NATURE 



203 



tnent. One real grievance, at any rate, is partly 

 met. \o guarantee is, however, offered that exist- 

 ing facilities generally given to women will be con- 

 tinued. They are now admitted to laboratories and 

 lectures only by the; courtesy of professors and 

 other teachers. Cambridge is at present suffering 

 from severe pressure on its accommodation. Under 

 Report B women might well be crowded out from 

 laboratories to make room for members of the 

 University — this is fully recognised by the sup- 

 porters of Report B; that is to say, the report 

 amounts to a desire to assist in the teaching of 

 women so long as the number of men students 

 leaves room for them and no longer. It is no 

 wonder that the councils of the women's colleges 

 at Cambridge have emphatically repudiated such 

 a scheme, and have declared that if Report B is 

 adopted at Cambridge they would take no steps 

 to promote the incorporation of Girton and Newn- 

 ham Colleges as a separate University. It is no 

 longer possible, in our view, for a university, in 

 sorting out its excess applicants for entry, to take 

 sex as the first and supreme test : intellect and the 

 needs of the nation are both safer tests in the 

 interest of the university and of learning. 



One more point in which Report B singularly 

 fails to make good the claims of its supporters 

 may be briefly mentioned. As regards the ad- 

 mission of women to the men's colleges, and 

 through the colleges to the University, it leaves the 

 door wide open as it has stood since the Sex Dis- 

 ability (Removal) Act. It is Report A, and not 

 Report B, which takes safeguards against what 

 is admitted on all sides to be undesirable. It is 

 Report A which, with this precaution, gives 

 women the fullest equality of opportunity with 

 men inside the University. 



Lunar Tables. 

 Tables of the Motion of the Moon. By Prof. 

 Ernest VV. Brown, with the a.ssistance of 

 Henry B. Hedrick. Sections i. and ii., pp. xiii 

 -t- 140-^39; section iii., pp. 223; sections iv., 

 v., vi., pp. 99+56-H02. (New Haven: Vale 

 University Press; Ix)ndon : Humphrey Milford ; 

 Oxford University Press, 1919.) Price, 3 vols., 

 4 guineas net. 



'HE appearance of Prof. E. VV. Brown's lunar 



tables marks the accomplishment of an 



duous task of the highest importance to astro- 



omy. In. the two centuries which have elapsed 



llnce the time of Newton more than a score of 



ables have been published. The majority of them 



naturally, belong to the eighteenth century, and 



NO. 2659, VOL. 106] 



no longer possess any practical inwrest apart from 

 the theories on which they were based. If they 

 did not always mark any very distinct advance in 

 accuracy beyond their predecessors, they generally 

 aimed at including a greater number of inequali- 

 ties more precisely determined, and systematic 

 observation of the moon was all the time accumu- 

 lating the material which could be used for com- 

 parison with theory and the better determination 

 of the fundamental constants. Newton himself 

 discussed eight lunar inequalities. Euler in his 

 memoir of 1772 included twenty-one inequalities 

 each in the longitude and the radius vector and 

 sixteen in the latitude. This was only a begin- 

 ning. As time went on and the standard of 

 achievement grew more exacting it is not surpris- 

 ing to find that the number of men who possessed 

 both the ability and the patient energy to elabor- 

 ate complete and independent theories of the 

 moon's motion and to reduce them to the form of 

 practical tables became notably smaller. Thus 

 when Burckhardt's tables of 1812 had once been 

 adopted in such annual publications as the 

 Nautical Almanac, overcoming the rival claims 

 first of Biirg and later of Damoiseau, they con- 

 tinued in use for the best part of half a century, 

 although their deficiencies ultimately amounted 

 almost to a scandal, and their form rendered it 

 particularly difficult to reconstruct the underlying 

 theory and to apply the needful corrections. A 

 serious error in the parallax according to these 

 tables was found and corrected by Adams. 



The Greenwich lunar reductions undertaken by 

 Airy, by which the results of eighty years' ob- 

 servations were made available, proved the need 

 for greatly improved tables, and provided the most 

 valuable material on this side for making an 

 advance. By that time it was known that Hansen 

 was engaged in lunar researches having for their 

 ultimate object the preparation of entirely new 

 tables, and their appearance was eagerly awaited. 

 But for a time difficulties threatened to intervene. 

 Born in Schleswig in 1795, Hansen is an out- 

 standing example of that singularly rare class, 

 the self-taught mathematician. Owing nothing to 

 academic education, he succeeded Encke in 1825 

 in the direction of the observatory at Gotha, and 

 thereafter until the end of his long life refused 

 all offers of preferment, though observatory and 

 stipend were alike of the most modest. In these 

 circumstances he received help from the Danish 

 Government, but when this was discontinued in 

 1848 owing to financial stringency and the steady 

 progress of the work was in danger, the British 

 Admiralty came to the rescue on the representa- 

 tion of Airy in 1850, and not only provided the 

 comparatively small sum needed to complete the 



