•268 MECHANICAL PERFECTION. 



have feet of the structure under consideration have 

 slender bills, their food is very varied, and the only 

 habit in vt'liich they all agree is that of being able not 

 only to adhere by the feet, but to move about upon 

 almost any form of surface, or in almost any position. 

 Considered as mechanical structures, acting in con- 

 cert with the whole organisation of the birds, these 

 are, perhaps, the most extraordinary of all the varied 

 forms which birds possess. They act in concert with 

 the whole structure of the birds ; and thus, though 

 the mechanical contrivance that appears in them, 

 taken singly, is not very striking, yet it becomes 

 remarkably so when we consider bird and foot jointly, 

 and notice how the varying pressures which the weight 

 of the body gives in all the numerous positions which 

 it can assume, contribute almost equally to render 

 more firm and sure the hold taken by the feet. One 

 of the greatest beauties in those displays of the 

 mechanics of nature, and one of the greatest superior- 

 ities which they evince over all that human ingenuity 

 can contrive, is the wonderful simplicity with which 

 what, to us, seems the most difficult of all purposes, is 

 accomplished. When we have a mechanical difficulty 

 to overcome, we complicate part upon part, and often 

 defeat our object, because the artificial clogs and hin- 

 derances which we thus produce, are greater than the 

 difficuhy which we sought to overcome ; and thus we 

 produce a negative efiect instead of a positive one, 

 and are further from our object at the end of our 

 labour than at the beginning ; but when we examine 

 nature, we find that the very difficulty itself becomes 

 one of the most effective means by which it is over- 

 come, — as in the case of these singularly footed birds, 

 the weight which the feet have to sustain is actually 

 converted into a means of sustaining it. 



