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 unfortunately leave to other surveys the merit of practically testing and introducing the new method, as our appropriations 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 Cellérier was appointed to join him, since the problem essentially was a theoretical one. The Sixth General Conference of _Die Europäische Gradmessung_ met September 13-16, 1880, in Munich.[67] Topic III, part 7 of the program was entitled "On Determinations of Gravity through pendulum observations. Which construction of a pendulum apparatus corresponds completely to all requirements of science? Special report on the pendulum." The conference received a memoir by Cellérier[68] on the theory of the double pendulum and a report by Plantamour and Cellérier.[69] Cellérier'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 pendulum 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 Plantamour and Cellérier 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.