A course of experiments in physical measurement (1897)
Whiting, Harold, d. 1895 · Boston, D.C. Heath and Co. · leaf 427
shade, and theiron-filings removed. The surface covered by the iron-filings sliould nothave been affected by the light; hence the arrange-ment sliown in Fig. 195 should be represented by awhite tracing on a blue ground. To make the printpermanent, it is necessary to soak it in water forabout ten… … Fig. 196. the print should be protected from excessive lighteither from the sun or from the skj. It may be illu-minated freely by lamplight or gaslight. The magnet is now to be placed over the print, di-rectly above its former position. A small compasswith a needle not more than 1cm. long, is to be…
Physics
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