Sarrui and sonic Allied Mechanisms. 



805 



The whole forms a closed kinematic chain of six pieces. 

 Seven being the normal number of pieces in a closed kine- 

 matic chain necessary to ensure freedom of one degree, it 



Fig. 3. 



A 



T 



R 





S 





B 



i 



U 



The hinge TV of fig. 1 being- disconnected, the mechanism 

 flattens out as shown here in plan. 



follows that the mechanism of Sarrut belongs to a special 

 class of mechanisms, with only six pieces, possessing singularly 

 and exceptionally one degree of freedom. 



1%. 4. 



The general mechanism of class (a). The hinges of A are 

 non-intersecting, as are also the hinges of* B. 



§ 3. It is instructive to compare the mechanism of Sarrut 

 with a certain generalized form to which it stands in the 

 relation of a degenerate case. Retaining the same number 



of piece- "and hinges, let it be supposed (figs -1, 5, 6) that 



