This book assembles 21 essays on the history of mechanics and mathematical physics written by David Speiser. Covering a period from the beginning of the seventeenth century to the eighteenth, the essays discuss developments in elasticity, rigid bodies, gravitation, the principle of relativity, optics, and first principles. They examine the work of Galileo, Huygens, Newton, Leibniz, the Bernoullis, Euler, Maupertuis, and Lambert.