Edinburgh New Philosophical Journal (1855) Edinburgh New Philosophical Journal edinburghnewphil11855 Year: 1855 314 James Elliot on certain it comes directly under the body of the top, as before.' This theory may, at first sight, seem plausible, but is liable to three fatal objections. First,—an inclined cylinder, rolling upon one end, never would roll towards the centre, but, on the contrary, would continually deviate further from it, unless its upper extremity were supported. Second,—the cause would cease, and the top would immediately fall, whenever any small hollow confined its point to o
Edinburgh New Philosophical Journal (1855) Edinburgh New Philosophical Journal edinburghnewphil11855 Year: 1855 314 James Elliot on certain it comes directly under the body of the top, as before.' This theory may, at first sight, seem plausible, but is liable to three fatal objections. First,—an inclined cylinder, rolling upon one end, never would roll towards the centre, but, on the contrary, would continually deviate further from it, unless its upper extremity were supported. Second,—the cause would cease, and the top would immediately fall, whenever any small hollow confined its point to one spot, as frequently happens. And, third,—if the standing of the top depended upon the thickness of the point, the finer the point'the more difficult it would be to keep up the top; and, if the peg could be ground to a mathematical point, the top would invariably and instantly fall. It is needless to say that such a conclu- sion is contrary to common observation, which shows us that, in mathematical language, the tendency to fall is no func- tion of the fineness of the point. In comparing the motions of the top with those of the earth, I thought that I perceived the true reason of the top's standing, viz., that the tendency to fall is converted by the rotation into the conical motion of the axis which I have be- fore described. But, to render this clear, let us commence with the common form of the top in which the centre of gra- vity is above the centre of motion, and let us suppose, for the sake of simplicity, the top to consist of a single circular plate, or, if we choose, we may take a top of any form, and suppose its whole mass to be concentrated in a single circular sec- tion perpendicular to the axis, and the whole weight of that section to be again collected into one circumference, as a hoop around an axis. Further, suppose such a top al- ready inclined to one side, as in the following diagram, CP being the axis, AB the circular sec- tion, or rather the circumfer
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