. Bulletin - United States National Museum. Science. ,, CL & 1 igure 8. -Completely useless arrangement of vertical coil and horizontal, unmagnetized needle, presented in the Edinburgh Philosophical Journal of 1821 as "Poggendorf's Galvano-Magnetic ; Almost every aspect of Poggendorf's instrument has been incorrectly represented. The nearly simultaneous creation by Schweigger, Poggendorf and dimming of an arrangement con- sisting of a coil of wire and a compass needle provided the first primitive version of a device to fill that need. 11 appears that Schweiggcr is clear
. Bulletin - United States National Museum. Science. ,, CL & 1 igure 8. -Completely useless arrangement of vertical coil and horizontal, unmagnetized needle, presented in the Edinburgh Philosophical Journal of 1821 as "Poggendorf's Galvano-Magnetic ; Almost every aspect of Poggendorf's instrument has been incorrectly represented. The nearly simultaneous creation by Schweigger, Poggendorf and dimming of an arrangement con- sisting of a coil of wire and a compass needle provided the first primitive version of a device to fill that need. 11 appears that Schweiggcr is clearly entitled to credit for absolute priority in the discovery, but the original sources suggest that both his understanding 11I the device and the subsequent researches he performed with it were markedly inferior to those of the other independent discoverers. In using the generic label, "Schweigger's Multiplier," there have been historical examples of attributing to Schweigger considerably more sophistication than is justified. Figure 7 shows an instrument designed by Oersted in ; w hich he sa) s "differs in only minor partic- ulars from that of M. ; n comparing figure 7 with figures 3, 4, or 5, the remark seems overly generous. The history of the multiplier instruments has had its fair share of erroneous reports and misleading clues. A fine example is the illustration of figure 8, taken from what is often quoted as the first report in English on Poggendorf's ''Galvano-Magnetic ; 31 The sketch is the editor's interpretation of a verbal description given him by a visiting Danish chemist who, in turn, had received the information in a letter from Oersted. It incorporates, faithful to the de- scription, a "spiral wire . . established vertically," with a needle "in the axis of the spiral," yet by mis- understanding of the axial relations and of the ratio of length to diameter for the coil, a completely mean
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