Instrumental

Inaccurate measurements compromised Polhem's data. Because the pendulum in the clock he used was not of the proper length, he arrived at incorrect values for the speed of the waterwheel and hence incorrect values for the output. Polhem tried in 1710 to reduce all these figures to their proper value by means of a correction coefficient, but found the work "so difficult and tedious, that no amount of patience would have sufficed." More seriously, the protractor he used to measure the inclination of the water trough gave different readings as the waterwheel was placed at different levels.

[15] Lagerhjelm, Hydrauliska försök , 2, 2–49.

[16] Ibid., preface. Cf. Lindqvist, Technology on trial , 87–9.

Polhem confided to his assistant: "In fact between ourselves, this work is as useful as a fifth wheel on a carriage."^[17]

Lagerhjelm proclaimed explicitly his awareness that calibrated precision instruments were essential if the experiments were to be reproducible and the results of general value. He made linear measurements using "a precisely graduated decimal scale two Swedish feet in length" produced by Johan Gustaf Hasselström, purveyor of mathematical instruments to the Royal Swedish Academy of Sciences. Lagerhjelm also employed "a set of weights calibrated against the Swedish original standard, which is kept in the Archives of the Royal Treasury," and a balance constructed by Gabriel Collin, manufacturer of optical instruments for the Academy, and watched a clock borrowed from the astronomical observatory of the University of Uppsala.^[18]

In quality of instruments, Lagerhjelm enjoyed a significant advantage over Polhem. Polhem had used the most accurate instruments he could acquire or construct. Over the course of the 18th century, however, a real market for scientific instruments had developed in Sweden. The market was largely the creation of the Royal Swedish Academy of Sciences, established in 1739. Rivals for this market competed in precision. Instrument-makers like Daniel Ekström, Hasselström, and Collin won the right to call themselves "Purveyors to the Royal Swedish Academy of Sciences";^[19] this distinction implied to prospective customers that every instrument produced in their workshops promised the highest possible degree of precision. Market pressures did thus increase the degree of precision, and the market itself was a result of the establishment of the Academy. Before then, no Swedish instrument-maker could acquire such status; hence there had been little or no competition in degree of precision.

[17] Axel Liljencrantz, ed., Christopher Polhems brev (Uppsala: Almqvist & Wiksell, 1941–6), 37–8.

[18] Lagerhjelm, Hydrauliska försök, 1 , 25–6.

[19] Cf. Sten Lindroth, Kungl. Svenska Vetenskapsakademiens historia 1739–1818 , 2 vols. (Stockholm: Almqvist & Wiksell, 1967), 1 , 789–815, 2 , 519–38, and Svensk lärdomshistoria: Frihetstiden (Stockholm: Norstedt, 1978), 373–6; Gunnar Pipping, The chamber of physics: Instruments in the History of Sciences Collections of the Royal Swedish Academy of Sciences (Stockholm: Almqvist & Wiksell, 1977).

In this way, the institutionalization of Swedish science contributed to the increased degree of precision in scientific instruments during the late 18th century, a development that contributed to the quantification of technology.