Borda and Cassini, Kater, and Bcsscl, respectively, 

 had made historic determinations. The Permanent 

 Commission, in w hose sessions Peirce also participated, 

 by resolutions adopted the report of the Special 

 Commission on the Pendulum. 90 



During the months of January and February 1876, 

 Peirce conducted obsen .it i<mv m the Grande Salle du 

 Meridien .it the observatory in Paris where Borda, 

 Biot, and Capt. Edward Sabine had swung pendu- 

 lums early in the 19th century. He conducted obser- 

 vations in Berlin from April to June 18~6 and, by 

 experiment, determined the correction for flexu 

 be applied to the value of gravity previously obtained 

 with the Prussian instrument. Subsequent observa- 

 tions were made .it Kiw . Alter his return tO the 



United States on August 26, 1876, Peirce conducted 

 experiments at the Stevens Institute in Hoboken, 

 New Jersey, where he made careful measurements of 

 the flexure of the stand by statical and dynamical 

 methods. In Geneva, he had secured the construc- 

 tion of a vacuum chamber in which the pendulum 

 could be swung on a support which he called the 

 Geneva support. At the Stevens Institute, Peirce 

 swung the Repsold-Bessel pendulum on the Geneva 

 support and determined the effect of different pres- 

 sures and temperatures on the period of oscillation of 

 the pendulum. These experiments continued into 

 1878. 61 



Meanwhile, the Permanent Commission met Octo- 

 ber 5-10, 1876, in Brussels and continued the discus- 

 sion of the pendulum.'-' Gen. Baeyer reported on 

 Pence's experiments in Berlin to determine the flexure 

 of the stand. The difference of 0.18 mm. in the 

 lengths of the seconds pendulum as determined by 

 Bessel and as determined by the Rcpsold instrument 

 agreed with Peirce's estimate <>( error caused by 

 neglect of flexure of the Repsold stand. Dr. Hirsch, 



,0 Ibid. See report fur fifth session, September 2S. 1875. 



"The experiments at tin- Stevens Institute, Hoboken, urn- 

 reported by Peirce to the Permanent Commission which met 

 in Hamburg, September 4-8, 18~8, and his report was pub- 

 lished in the general Berichl for 18~8 in the Verhandlungen 

 der torn J bis S September 187S in Hamburg Veremiglen Permanent™ 

 Commission der Europaischen Gradmessung (Berlin, 18"''), pp. 1 16- 

 120 Assistant J. E. Hilgard attended for the U.S. Coast and 

 Geodetic Survey, ["he experiments are described in detail in 

 C. S. Peircf, "On the Flexure of Pendulum Supports," Report 

 of the Superintendent of the I '.S. Coast and Geodetic Survey for 1880— 

 SI (Washington, 1883), app. no. 14, pp. 359-441. 



" I 'erhandlungen der torn 5 bis 10 ■ Brussels I >r- 



einigten Permanenten Commission der Europaischen Gradmessung 

 (Berlin, 18 ). See report of third session, October 7, 18"6. 



speaking lot the Sv< iss survey . and Prof, von <">ppolzcr, 



speaking lor the Austrian survey, ((intended, however, 

 that then st.inds possessed sufficient stability and th.it 

 the results found by Peine applied only to the stands 

 .mil I uses investigated by him. 1 he Pi rmani a! 

 mission proposed further studv ol the pendulum. 

 The I'iith < .1 hi i ,il ( lonfei en< e 1 1 



was held from September 2~ to Octo 

 1877, in Stuttgart. Peirce had instructions from 

 Supt. Patterson oi the I s ( oast Survey to attend 

 this conference, and on arrival presented a letter ol 

 introduction from Patterson requesting th.it he. 

 Peirce, be permitted to participate in the sessions. 



I port invitation from Prof. Plantamour, .is approved 



n. Ib.ine/, president of the Permanent Commis- 

 sion, Peirce had scut on July 13, 1877, from New 



York, the manuscript of a memoir titled "De 



I'Influence de la flexibilitd du trepied sur l'oscillation 



du pendule a reversion." This memoir and others 

 by Cellerier and Plantamour confirming Peirce's 



work were published ,is ,i p| icnd it es to the proceedings 

 of the conference. As appendices in Peirce's contri- 

 bution were published also two notes by Prof, von 

 Oppolzer. At the second session on September 29, 

 1877, when Plantamour reported that the work of 

 Hirsch and himself had confirmed experiment. illy 

 the independent theoretical vvork of Cellerier and the 

 theoretical and experimental work of Peirce on 

 flexure, Peirce described his Hoboken experiments. 



During the discussions at Stuttgart on the flexure 

 of the Repsold stand, Hervd Faye, president of the 

 Bureau of Longitudes. Paris, suggested that tin sway- 

 ing "I the stand during oscillations of the pendulum 

 could be overcome by the suspension from one support 

 of two similar pendulums which oscillated with equal 

 amplitudes and in opposite phases. This proposal 

 was criticized by Dr. Hirsch, who declared that exact 

 observation of passages of a "'double pendulum" 

 would be difficult and that two pendulums swinging 

 so close together would interfere with each other. 

 The proposal of the double pendulum came up again .it 

 the meeting of the Permanent Commission at Geneva 

 in 1879. M On February 17, 1879, Peine had com- 

 pleted a paper "On a Method of Swinging Pendulums 

 for the Determination of Gravity, Proposed by M. 



e3 Verhandlungen der mm 27 September his 2 Oktober \ 

 Stuttgart ahgehaltenen junjten allgemeinen Conferen.z der Euro- 

 paischen Gradmessung (Berlin, 18~8). 



" Verhandlung der torn 16 ' in Gen/ Ver- 



einigten Permanenten Commission der Europaischen Gradmessung 

 (Berlin, 1880). 



PAPER 44: DEVELOPMENT OF GRAVITY PENIM II MS IN THE 1 9TH CENTLRV 



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