A General Theorem in Kinematics

Abstract

PROF. EVERETT (ante, p. 99) has overlooked in the introductory paragraphs of Prof. Schell's paper, to which he refers for the original statement of the theorem re-discovered by Prof. Minchin, the acknowledgment: “Der Mittelpunkt der Beschleunigungen und jene beiden Kreise wurden bereits 1853 von BRESSE gefunden.” The reference is to the Journal de l'École Polytechnique, tom, xx., “Mémoire sur un Théorème nouveau concernant les Mouvements Plans, etc.” By means of the “two circles” Bresse determines the point c (J) “qui aura une accélération totale nulle” (p. 82), and then by very ingenious application of kinematic principles deduces those relations to it which any arbitrary point (P) has, as given by Prof. Minchin. Bresse names c “second centre instantané de rotation.”