Cumming, Linnæus, b. 1843. [from old catalog] · New York, D. Van Nostrand · leaf 62
tism, 43 shows an inclination of 90°, i.e. stands vertical. The needlemust then be in the plane at right angles to the meridian, forin this position the horizontal component of the earths pull isbalanced by an increased pressure on the south and diminishedpressure on the north bearing of the… … Fio. 35. zontal circle is read, when each end of the needle points to90°, and also when the faces of the needle have been reversed,either by turning the instrument through half a revolutionor by lifting the needle from its supports and reversing thebearings. The mean of the four readings so…
Electricity
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