A manual of electricity, magnetism and meteorology (1844)
Lardner, Dionysius, 1793-1859, Walker, Charles Vincent, 1812-1882 · London Longman, Brown, Green & Longmans · leaf 264
sregular. The length of these rays was very various, butthey all converged to that point of the heavens indicatedby the direction of the southern pole of the dippingneedle, as indicated in fig. 108. Sometimes they wereprolonged to the point where their directions intersected,and formed the summit… … Fig. 109.
Atmospheric electricity · Electricity -- Early works to 1850 · Magnetism
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