Electricity for public schools and colleges (1891)
Larden, W. (Walter), b. 1855 or 6 · London : Longmans · leaf 59
ECTRICITY en. III. The general method, without detail, is as follows. With the telescope observe some distant object whose geo-graphical bearing is known, e.g. some star not far from thehorizon. Read off the position of the index on the graduatedcircle ; and, from knowledge of the bearing of the… … Fig. i. which, if the instrument be perfectly made, will be done by turn-ing the telescope round till the end of the needle is viewed.Read the position of the index. The difference between thisreading and the last will be the angle between the magnetic axisof the needle and the geographical north…
Electricity
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