pages: latestmagicbeing00hoff.pdf, 156
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latestmagicbeing00hoff.pdf | 156 | 140 LATEST MAGIC for in the pack, and is found to bear a more or less appropriate answer to the question asked. The movements of the pointer are governed by the fact that, imbedded in the mahogany mount surrounding the base of the bell glass, is a piece of thick steel wire, strongly magnetised, and extending half way round the circle. The pointer, though SO coloured as to have the appearance of brass, is in reality a magnetic steel needle, and therefore when resting on the pivot and covered by the glass, will automatically move round till it comes to rest between the two magnetic poles formed to the opposite ends of the hidden wire. The operator can therefore, by placing the glass cover accordingly, cause the indicator to stop at any part of the dial that he pleases. It remains to be explained what guides him in the manipulation of the glass, SO as to cause the needle to stop at the point he desires. It will be remembered that, attached to the knob at the top of the glass, is a loop of ribbon, serving to suspend the glass in use from the forefinger, as shown in Fig. 28. But the loop has in truth a much more important function than this. Before the loop is formed, the ribbon is tied tightly round the neck of the knob, previously waxed to prevent its slip- ping round, and the knot is SO placed that it shall exactly correspond with that pole of the magnet to which the point of the needle is intended to be in use attracted. This done, a loop is formed with |