 ### Periodic Center of Motion

Illustration showing the periodic center of motion as it often happens when two positions of a line… ### Centroid

Illustration showing a centroid, "the curve passing through the successive positions of the instantaneous… ### Motion of Open Curves

"Since these curves are not closed, one pair cannot be used for continuous motion; but a pair of such… ### Comparative Surfaces Of A Cylinder And Sphere

Illustration used to compare the surfaces of a cylinder and a sphere. ### Surfaces Of A Cylinder

Illustration of a cylinder showing, "If a piece of paper is fitted to cover the convex surface of a… ### Rolling of Equal Ellipses

"If two equal ellipses, each turning about one of its foci, are placed in contact in such a way that… ### Rolling of Equal Hyperbolas

Illustration of the rolling of equal hyperbolas. If two equal hyperbolas are placed so that the distances… ### Rolling of Equal Parabolas

Illustration of the rolling of equal parabolas. "The two parabolas may be considered as two ellipses… ### Projection Of An Irregular Surface

Illustration of an irregular surface abdc projected upon the flat surface ABCD. ### Lens

"A lens is a transparent body the two refracting surfaces of which are curved, or one of which is curved… ### Double Convex Lens

"The shape of the double convex lens, d, c, is that of two plano-convex lenses, placed with their plane… ### Construction of Logarithmic Spiral

Illustration showing how a rolling logarithmic spiral can be constructed by taking successive values… ### Rolling of Logarithmic Spirals

Illustration showing the rolling of two logarithmic spirals of equal obliquity. ### Rolling of Non-cylindrical Surfaces

Illustration showing that the rolling of non-cylindrical surfaces. "If the angular velocity ratio of… ### Surfaces Of A Prism

Illustration of a pentagonal prism showing, "If a piece of paper is fitted to cover the convex surface… ### Section of Rolling Surfaces

Illustration showing a section of the rolling surfaces by a plane perpendicular to their straight line… ### Logarithmic Spiral Sector

In this illustration, "the driven surface of the slide coincides with the tangent to the spiral, the… ### Motion of Translation

Illustration showing the motion of translation of two parallel motions.