8 74 



NA TURE 



[December 30, 1922 



tion is made at the capricious decision of a body of 

 resident conservatives who, through the Senate, wield 

 a wholly disproportionate power on matters vitally 

 affecting the well-being of the University." Yet he 

 had just admitted that only thrice in twenty-five years 

 has the Senate come up in force, and that only once 

 did it outvote the resident majority. His picture of 

 wicked conservatives " constantly " calling up non- 

 residents to oppose progressive Radicals is just as 

 devoid of fact as the assumption that Radicals are 

 always progressive. 



When, in ioio, a like charge was made against the 

 Senate, I recited in the Senate-House a list of much- 

 needed reforms and progressive measures (in all of 

 which I was concerned), e.g. a proper audit and 

 control of Departmental funds, the reform of the 

 Press, the reform of the Fizwilliam Museum, the 

 founding of the Departments of Anthropology and of 

 Architecture, etc., etc. (all of which had later to be 

 carried out), and I charged to their faces the Radical 

 leaders who then controlled the Council, with heading 

 the obstruction to all these reforms. No one then or 

 since has disputed my allegations. The suggestion 

 that resident conservatives are an insignificant body 

 is disproved by our important gains in the late 

 elections to the Council (even without the much- 

 needed secret ballot). My critic does not deny that 

 the proposals of the Report respecting the powers of 

 the Senate, the constitution of the Council and of the 

 Board of Studies and Research go much further than 

 the proposals made by the committee of younger 

 graduates (men under 40) who represent the most 

 advanced opinion among residents. They wish that 

 the ultimate decision on statutes should rest with the 

 Senate, and that the professoriate should keep its 

 representation on the Council, and have some on the 

 proposed new Board of Studies. 



William Ridgewav. 

 Flendyshe, Fen Ditton, Cambridge, 

 December 2. 



Leaving on one side the more personal aspects of 

 Sir William Ridgeway's letter — his zeal for progressive 

 reforms arjd the disingenuousness of his critic — a reply 

 may be made to one or two of the points raised by 

 him. He is mistaken in saying that the committee 

 of younger graduates (men under 40) represent the 

 most advanced opinion among residents. They have 

 not unfairly been nicknamed " The Cambridge 

 Whigs." Even this body, however, has suggested 

 that members of the General Board (or Board of 

 Studies and Research) should be nominated by the 

 Council and that the Board should be reduced iii size 

 by abandoning the direct representation of the 

 Special Boards of Study. It is held by many, who 

 are equally keen with Sir William Ridgewav <m the 

 independent development of educational policy in the 

 University, that the best solution lies in a small 

 Board akin to the present Board of Research Studies. 

 well balanced between the different faculties and 

 working in close co-operation with the Special Boards. 

 As to the question whether an appeal against the 

 House of Residents would ever be made under the 

 Commission's scheme, the writer differs absolutely 

 from Sir William Ridgeway. Differences of opinion 

 are too acute, and the fighting spirit of both sides too 

 strong, to allow certain proposals to pass without a 

 stern contest at every possible point. 



The Writer of the Article. 



Gravity Variations. 



Mr. R. 1 1. ( Ildham's letter 111 Nature of November 

 18, p. 665, makes the disquieting suggestion that the 

 force oi gravity at Dehra Dun may be subject in 



NO. 2774, VOL. I 10] 



fluctuations. The changes that he points out in the 

 times of oscillation of the Indian pendulums can, 

 however, be quite reasonably attributed to alterations 

 in the lengths of the pendulums and errors of observa- 

 tion, and are not, in my opinion, so grave as to warrant 

 a belief in anything more fundamental. As Mr. Old- 

 ham says, there is neither proof nor disproof of a change 

 in gravity. But the discussion undoubtedly indicates 

 a weak spot in the Indian operations, namely the 

 connexion of Dehra Dun with Kew Observatory, 

 which is the base station for this country. It rests 

 on the results obtained with four pendulums swung at 

 Kew and then transported to Dehra Dun and swung 

 there. The pendulums have never been brought back 

 to this country, so if they suffered any changes of 

 length on the journey from Kew to Dehra Dun the 

 value of g found at the latter place will be erroneous. 



It would, of course, have been necessary to under- 

 take a return journey long ago if no corroboration of 

 the result of the first journey had been available. 

 There was, however, the strong corroboration afforded 

 by Hecker's observations in 1905, as mentioned by 

 Mr. Oldham, and the valuable though less powerful 

 evidence obtained by Alessio in 1906. Hecker's result 

 was of special value because at Jalpaiguri his apparatus 

 was set up alongside the Indian one and simul- 

 taneous observations were made using the same clock. 

 Tims there was good reason to believe that the effects 

 of fluctuations of temperature and variations in the 

 clock's rate — the chief sources of uncertainty — would 

 be the same on both sets of observations, and that 

 therefore the check on the Dehra Dun value of g 

 would be nearly as satisfactory as if Dr. Hecker's 

 pendulums had been swung at Dehra Dun itself. 



The links forming the connexion of Dehra Dun with 

 the value of g determined at Potsdam are as follows : 



Result. 



Potsdam — Kew (Putnam, 1900) 



Kew — Dehra Dun (Indian operations, 1904) 979-063 



Potsdam — Jalpaiguri (Meeker, 1905) 



Jalpaiguri — Dehra Dun (Indian, 1905) . 979-065 



Potsdam — Genoa 



Genoa — Bombay (Alessio, [906) 



Bombay — Dehra Dun (Indian, 1904) . 979-059 



The probable error of each of these results may be 

 estimated to be between ±0-003 an d ±0-005. The 

 agreement between them is therefore better than the 

 probable errors would have allowed us to anticipate. 



Commander Alessio's observations in 1913-14, hi m - 

 ever, give a value of 979-079 for^ at Dehra Dun, which 

 differs from the above by nearly four times the 

 probable error. 



Alessio's observations were most carefully made 

 with a strong equipment of eight pendulums, and 

 carry great weight. Thev have not, so far as I am aware, 

 been published in detail as yet, and it is not possible 

 to form a iinal judgment on them ; but in the article 

 in the Rivista Marittima quoted by Mr. Oldham, there 

 is a remark which may perhaps indicate a weak 

 point. Commander Alessio savs that the comparison 

 of the times of oscillation of the pendulums at Genoa 

 before and after the journey show that certain changes 

 had taken place in the lengths of the individual pen- 

 dulums, but that fortunately the length of the mean 

 of the eight pendulums had remained absolutely un- 

 changed. If the changes in the individual pendulums 

 were large, and if they, or any of them, took place 

 before the pendulums reached Dehra Dun, then the 

 deduced value of g at Dehra Dun may be burdened 

 with a considerable error. 



Whatever opinion may be formed wdien the whole 

 of the details of Commander Alessio's work are avail- 



