From the PREFACE. Our exact knowledge of Rotary Motion, as of Dynamics in general, dates from the time of Newton. Euler, Laplace, Lagrange, Poisson and Poinsot are illustrious names in the development of the theory. Foucault, in 1855, demonstrated the rotation of the earth by means of the gyroscope, and gave it its name. Its practical applications date from yesterday. These began with the Griffin Grinding Mill, and have been followed by the Howell...