54 Mayow 



the rigid body delineated in Fig. 4. But now if the 

 rod be bent so as to represent the concave surface of 

 the rigid body while the string represents the convex, 

 and the string meanwhile has been loosened at one of 

 its ends so that it can be lengthened as the rod bends 

 so as to remain parallel to it, then the bent rod with 

 the string parallel to it and the rods at its ends will 

 represent the rigid body bent in the first manner and 

 delineated in Fig 5. 



But if the string is fastened at each end so that it 

 cannot be lengthened when the rod is bent, you will 

 see that the string which represents the convex surface 

 of the rigid body passes inwards and is drawn towards 

 the stick or concave surface exactly like the rigid body 

 bent in the second manner and delineated in Plate 

 I-, Fig. 5. 



Further, if the string be hindered by any force from 

 being drawn inwardly when the rod is bent, then the 

 two little rods which represent the end planes of the 

 rigid body will be drawn inwards towards each other, 

 as is the case in a rigid body bent in the third manner 

 and delineated in Fig. 6. But in order that the rigid 

 body may be exhibited as it is bent in the said figure, 

 the rods at the end should not only be drawn towards 

 each other but also lengthened. 



Finally, if the rod be bent towards the string so as to 

 represent the convex side of the bent rigid body, and 

 the cord which now represents the concave side be 

 meanwhile shortened, but in such a way as to remain 

 parallel to the rod, you will have a representation of 

 a rigid body as it is bent in the last mode in Fig. 7. 



We have next to remark with respect to rigid bodies 

 that their branching parts are so mutually interlaced 

 and so firmly compacted that the rigid bodies can 

 neither be lengthened nor shortened without being 



