Abstract
I.—Gyrostatic Experiments in the Glasgow Classroom. WHEN I was a student, and afterwards when I was an assistant at Glasgow, Lord Kelvin lectured to his ordinary class twice a week, when he was not called away, and his subject was dynamics. About the middle of the session gyrostats made their appearance on the lecture-table, and we had wonderful gyrostatic experiments which filled us with delight, and gyrostatic questions in the weekly class-examinations which were equally productive of dismay. These gyrostatic questions, like many of our exercises in natural philosophy, were often of a numerical character. It is always a good thing to get down to numbers, and it is a most healthful mental discipline to be forced to “get the units right.” Our equipment for the solution of these problems was of the slightest, for Lord Kelvin was himself so keenly absorbed in observing the behaviour of the apparatus, that he rather frequently forgot to give us the full dynamical explanation of the curious evolutions which we beheld. I could follow the process of composition of angular momenta, and could see that the axis of resultant angular momentum turned at that rate; but why should that also be the rate of turning of the axis of figure? That was my special difficulty, and it was only afterwards, when I got the idea of steady motion, and saw how the general equation is obtained and how it breaks down into the conditions for steady motion, that the matter became clear. Then I f u,d moreover, that in the general case there are twG possible rates of turning. It is a good thing tc stimulate the curiosity of a student to make him find out things for himself: it is also an excellent thing to anticipate his difficulties to some extent, lest he grow weary and faint by the toilsome dynamical way.
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References
Abridged from the Sixth Kelvin Lecture, delivered at the Institution of Electrical Engineers, on January 28, by Prof. A. Gray, F.R.S.
Proceedings of the Royal Society, vol. viii, p. 150. 1856.
Loc. cit. above.
Proceedngs of the London Mathematical Society, vol. vi., p. 190. 1985 Math. and Phys. Papers. vol. iv., p. 533.
British Association Report, 1876, Transactions of Sections, p. 1.
Philosophical Transactions of the Royal Society, vol. cliii., p, 573, 1863.
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Lord Kelvin's Work on Gyrostatics 1 . Nature 94, 711–716 (1915). https://doi.org/10.1038/094711a0
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DOI: https://doi.org/10.1038/094711a0