18 EVOLUTION, OLD AND NEW. 



is occasionally requisite that the object end of the in- 

 strument be moved up and down as well as horizontally 

 or equatorially. For the vertical motion there is a 

 hinge upon which the telescope plays, for the hori- 

 zontal or equatorial motion, an axis upon which the 

 telescope and the hinge turn round together. And 

 this is exactly the mechanism which is applied to the 

 action of the head, nor will anyone here doubt of the 

 existence of counsel and design, except it be by that 

 debility of mind which can trust to its own reasonings 

 in nothing." * 



****** 

 " The patella, or knee-pan, is a curious little bone ; in 

 its form and office unlike any other bone in the body. 

 It is circular, the size of a crown-piece, pretty thick, a 

 little convex on both sides, and covered with a smooth 

 cartilage. It lies upon the front of the knee, and the 

 powerful tendons by which the leg is brought forward 

 pass through it (or rather make it a part of their conti- 

 nuation) from their origin in the thigh to their insertion 

 in the tibia. It protects both the tendon and the joint 

 from any injury which either might suffer by the rub- 

 bing of one against the other, or by the pressure of 

 unequal surfaces. It also gives to the tendons a very 

 considerable mechanical advantage by altering the line 

 of their direction, and by advancing it farther out of 

 the centre of motion ; and this upon the principles of 

 the resolution of force, upon which all machinery is 

 founded. These are its uses. But what is most observ- 

 able in it is that it appears to be supplemental, as it 

 * * Natural Theology.' ch. viii. 



