APPENDIX I. 191 



LINDEMANN (F.) Ueber unendlich kleine Bewegungen und uber 

 Krdftesysteme bet allgemeiner projectivischer Massbestimmung. 

 Math. Ann., yth Vol., pp. 56-143 (July, 1873). 



This is a memoir upon the statics and kinematics of a rigid 

 body in elliptic or hyperbolic space. Among several results 

 closely related to the Theory of Screws, we find that the cylin- 

 droid is only the degraded form in parabolic or common space 

 of a surface of the fourth order, with two double lines. 



WEILER (A.) Ueber die verschiedenen Gattungen der Complex* 

 zweiten Grades. Math. Ann., Vol. vii., pp. 145-207 (July, 

 1873). 



In this elaborate memoir the author enumerates fifty-eight 

 different species of linear complex of the second order. The 

 classification is based upon Rummer's surface, which defines 

 the singularities of the screw complex. 



BALL, (R. S.) Screw Co-ordinates and their applications to pro- 

 blems in the Dynamics of a Rigid Body. Transactions of 

 the Royal Irish Academy, Vol. xxv., pp. 259-327 (January 

 12, 1874). 



To trace a satisfactory connexion between an impulsive 

 screw and the corresponding instantaneous screw is the principal 

 object of this paper. It is here shown that to the instantaneous 

 screw, whose co-ordinates are Oi t . . . , 6 , corresponds an impul- 

 sive screw, whose co-ordinates are proportional to /A, . . ., / 8 0, 

 reference being made to the absolute principal screws of inertia. 



EVERETT (J. D.) On a new method in Statics and Kinematic*. 

 (Part I.) Messenger of Mathematics. New Series. 

 No. 39 (1874). 



This paper contains applications of quaternions. The opera- 

 tor v + Var ( ) is a " motor," and o- being vectors, the former 

 denoting a translation or couple, the latter a rotation or force. 



The pitch is S-. The equation to the central axis is p = P- 

 cr <r 



x<r. The work done in a small motion is - 



