Note 89 — Front matter (continued 8)

In 1902, Dr. P. Furtwängler[89] presented the mathematical theory of coupled pendulums in a paper in which he referred to Faye’s proposal of 1877 and reported that the difficulties predicted upon its application had been found not to occur. Finally, during the gravity survey of Holland in the years 1913-1921, in view of instability of supports caused by the mobility of the soil, F. A. Vening Meinesz adopted Faye’s proposed method of swinging two pendulums on the same support. [90] The observations were made with the ordinary Stückrath apparatus, in which four Von Sterneck pendulums swung two by two in planes perpendicular to each other. This successful application of the method—which had been proposed by Faye and had been demonstrated theoretically to be sound by Peirce, who also published a design for its application—was rapidly followed for pendulum apparatus for relative determinations by Potsdam, [91] Cambridge (England), [92] Gulf Oil and Development Company, [93] and the Dominion Observatory at Ottawa. [94] Heiskanen and Vening Meinesz state: