I. SPECIAL COLLECTIONS. 109 



77. Differential crank train (Romer). 



Numbers of teeth, 56 and 56, with apparatus for tracing diagrams. 



78. Differential crank train (Romer). 



Numbers of teeth, 56 and 57, with apparatus for tracing diagrams. 



79. Differential crank train (Romer). 



Numbers of teeth, 30 and 90, with apparatus for tracing diagrams. 



80. Hooke's joint. 



81. Universal joint (Blees). 



82. Universal joint (Polhem). 



83. Universal joint (Reuleaux). 



84. Universal joint (Klein). 



85. Universal joint (Klein). 



Simplified by Reuleaux. 



86. Double Hooke's joint. 



The velocity ratio here can be made constant. 



556. IV. Mechanisms for describing Straight Lines 

 (exactly or approximately). 



87. Roberts triangle, " parallel motion." 



88. Triangle motion, inverted, by Reuleaux. 



89. Elliptic linkwork (Nehrlich), 3rd form, inverted. 



90. Elliptic linkwork (Nehrlich), 3rd form, inverted. 



91. Hypocycloidal linkwork. 



92. Hypocycloidal linkwork, inverted, by Reuleaux. 



93. Epicycloidal linkwork, Reuleaux. 



94. Elliptic linkwork, inverted. 



With the whole motion. 



95. Tchebischeff's linkwork. 



Arranged so that it can be inverted. 



96. Conchoidal linkwork, 1st form. 



97. Conchoidal linkwork, 3rd form (Reichenbach). 



98. Conchoidal linkwork, 3rd form (Reuleaux). 



99. Lemniscoidal linkwork, 1st form (Watt). 



100. Lemniscoidal linkwork, 2nd and 3rd forms. 



101. Lemniscoidal linkwork, 1st form, inverted (Reuleaux). 



102. Lemniscoidal linkwork, 2nd and 3rd forms. 



Steam engine model with Watt's planet wheels. 



103. Sector mechanism (Reuleaux). 



Involute. 



104. Sector mechanism (Reuleaux). 



Cycloid. 



105. Sector mechanism (Reuleaux). 



Cycloid. 



106. Cartwright's mechanism. 



107. Maudsley's mechanism. 



108. Tchebischeff's mechanism. 



