394 THE MECHANICAL FUNCTIONS. 



!y reticulated surface of great extent, admirably calculated 

 to prevent the passage of the air through it, and to create, by 

 its motion, that degree of resistance which it is intended the 

 wing should encounter.* In feathers not intended for flight, 

 as in those of the ostrich, the fibrils are altogether wanting: 

 in those of the peacock's tail, the fibrils, though large, have 

 not the construction which fits them for clasping those of 

 the contiguous lamina; and in other instances they do so 

 very imperfectly. 



A construction so refined and artificial as the one I have 

 been describing, and so perfectly adapted to the mechanical 

 object which it is toansw^er, cannot be contemplated without 

 the deepest feeling of admiration, and without the most eager 

 curiosity to gain an insight into the elaborate processes, 

 v^^hich, we cannot doubt, are employed by nature in the for- 

 mation of a fabric so highly finished, and displaying such 

 minute and curious workmanship. It is only very recently 

 that we have been, admitted to a close inspection of the com- 

 plicated machinery, which is put in action in this branch of 

 what may be called organic architecture; and certainly none 

 is more fitted to call forth our profoundest wonder at the 

 comprehensiveness of the vast scheme of divine providence, 

 which extends its care equally to the perfect construction o% 

 the minutest and apparently most insignificant portions of 

 the organized frame, whether it be the down of a thistle, the 

 scales of a moth, or the fibrils of a feather, as well as to 

 the completion of the larger and more important organs of 

 vitality. 



Every bird, on quitting the egg, is found to be covered 

 on all parts except the under side, with a kind of down con- 

 sisting of minute filaments, collected in tufts, and resem- 



* A very clear account of the mechanism described in the text is given by 

 Paley, in the 12th chapter of his "Natural Theology." Many of the mi- 

 nuter details 1 have supplied from my own observations with the microscope. 

 The branched forni of the upper fibrils, and the reticulated structure of the 

 laminx themselves, when viewed witli a high magnifying power, are parti- 

 cularly beautiful microscopic objects. 



