(373) During the past few years, however, a new type has been introduced, of which there are now several examples, and which is rapidly superseding all others. Everyone is aware of the tendency of a rapidly revolving body, such as a humming top a little out of balance, to assume such a position that its axis is out of the perpendicular while its revolution is going on with absolute steadiness. The high rate of speed which is attained with ring spindles, running up to 11,000 revolutions per minute, produced as might be expected, a certain amount of vibration which it is desirable to avoid. Consequently, a spindle was produced in America to which the designation of the “top” or “elastic” spindle was given, and which was, while held in a long bearing at the top of the bolster, free to move at its foot until it found its position of steadiness. It was found, however, that the changes of position when the balance was disturbed were so abrupt that it was necessary to restrain the movement to a certain extent.
Fig. 189.
Fig. 190.J.N.
Fig. 188.J.N.
Fig. 191.J.N.
