Faye." In this paper, Peirce presented the results 

 of an analytical mechanical investigation of Faye's 

 proposal. Peirce set up the differential equations, 

 found the solutions, interpreted them physically, 

 and arrived at the conclusion "that the suggestion of 

 M. Faye ... is as sound as it is brilliant and offers 

 some peculiar advantages over the existing method of 

 swinging pendulums." 



In a report to Supt. Patterson, dated July 1879, 

 Peirce stated: "I think it is important before making 

 a new pendulum apparatus to experiment with Faye's 

 proposed method." 65 He wrote further: "The 

 method proves to be perfectly sound in theory, and as 

 it would greatly facilitate the work it is probably 

 destined eventually to prevail. We must unfor- 

 tunately leave to other surveys the merit of practically 

 testing and introducing the new method, as our appro- 

 priations are insufficient for us to maintain the leading 

 position in this matter, which we otherwise might 

 take." Copies of the published version of Peirce's 

 remarks were sent to Europe. At a meeting of the 

 Academy of Sciences in Paris on September 1, 1879, 

 Faye presented a report on Peirce's findings. 66 The 

 Permanent Commission met September 16-20, 1879, 

 in Geneva. At the third session on September 19, 

 by action of Gen. Baeyer, copies of Peirce's paper on 

 Faye's proposed method of swinging pendulums were 

 distributed. Dr. Hirsch again commented adversely 

 on the proposal, but moved that the question be 

 investigated and reported on at the coming General 

 Conference. The Permanent Commission accepted 

 the proposal of Dr. Hirsch, and Prof. Plantamour 

 was named to report on the matter at the General 

 Conference. At Plantamour's request, Charles Cel- 

 lerier was appointed to join him, since the problem 

 essentially was a theoretical one. 



The Sixth General Conference of Die Europdische 

 Gradmessung met September 13-16, 1880, in Munich. 67 

 Topic III, part 7 of the program was entitled "On De- 

 terminations of Gravity through pendulum observa- 

 tions. Which construction of a pendulum apparatus 

 corresponds completely to all requirements of science? 

 Special report on the pendulum." 



65 Assistants' Reports, U.S. Coast and Geodetic Survey, 1879-80. 

 Peirce's paper was published in the American Journal of Science 

 (1879), vol. 18, p. 112. 



65 Comptes-rendus de /' kademie des Sciences (Paris, 1879), 

 vol. 89, p. 462. 



87 Verhandlungen der vom 13 bis 16 September 1S80 zu Miinchen 

 abgehaltenen sechsten allgemeinen Conjeten; dei Europ'dischen Grad- 

 messung (Berlin, 1881). 



The conference received a memoir by Cellerier M on 

 the theory of the double pendulum and a report by 

 Plantamour and Cellerier. 1 '-' Cellerier's mathematical 

 analysis began with the equations of Peirce and used 

 the latter's notation as far as possible. His general 

 discussion included the results of Peirce, but he 

 stated that the difficulties to be overcome did not 

 justify the employment of the "double pendulum." 

 He presented an alternative method of correcting for 

 flexure based upon a theory by which the flexure 

 caused by the oscillation of a given reversible pen- 

 dulum could be determined from the behavior of an 

 auxiliary pendulum of the same length but of different 

 weight. This method of correcting for flexure was 

 recommended to the General Conference by Planta- 

 mour and Cellerier in their joint report. At the 

 fourth session of the conference on September 16, 

 1880, the problem of the pendulum was discussed 

 and, in consequence, a commission consisting of 

 Faye, Helmholtz, Plantamour (replaced in 1882 by 

 Hirsch), and Von Oppolzer was appointed to study 

 apparatus suitable for relative determinations of 

 gravity. 



The Permanent Commission met September 11-15, 

 1882, at The Hague, 70 and at its last session appointed 

 Prof, von Oppolzer to report to the Seventh General 

 Conference on different forms of apparatus for the 

 determination of gravity. The Seventh Conference 

 met October 15-24, 1883, in Rome, 71 and, at its 

 eighth session, on October 22, received a comprehen- 

 sive, critical review from Prof, von Oppolzer entitled 

 "Uber die Bestimmung der Schwere mit Hilfe ver- 

 schiedene Apparate." 7 - Yon Oppolzer especially ex- 

 pounded the advantages of the Bessel reversible 

 pendulum, which compensated for air effects by 

 symmetry of form if the times of swing for both 

 positions were maintained between the same ampli- 

 tudes, and compensated for irregular knife edges by 

 making them interchangeable. Prof, von Oppolzer 

 reviewed the problem of flexure of the Repsold stand 

 and stated that a solution in the right direction was 



68 Ibid., app. 2. 



69 Ibid., app. 2a. 



70 Verhandlungen der vom 11 bis zum 15 September 1SS2 im Haag 

 Vereinigten Permanenten Commission der Europiiischen Gradmessung 

 (Berlin, 1883). 



71 Verhandlungen der vom 15 bis 24 Oktober 1883 zu Rom abge- 

 haltenen siebenlen allgemeinen Conjercnz der F.mopaischen Gradmessung 

 (Berlin, 1884). Gen. Cutts attended for the U.S. Coast and 

 Geodetic Survey. 



72 Ibid., app. 6. See also, Zeitschrift fiir Inslrumentenkunde 

 (1884), vol. 4, pp. 303 and 379. 



326 



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