THE MECHANICAL WONDERS OP A FEATHER. 283 



Strip off from one side or both when we make a pen. The 

 separate pieces of which this is composed are called threads, 

 filaments, or rays^. Now, the first thing which an attentive 

 observer will remark is, how much stronger the beard of the 

 feather shows itself to be when pressed in a direction per- 

 pendicular to its plane, than when rubbed either up or down 

 in the line of the stem ; and he will soon discover, that the 

 thread of which these beards are composed are flat, and 

 placed with their flat sides towards each other ; by which 

 means, while*they easily bend for the approaching of each 

 other, as any one may perceive by drawing his finger ever 

 so lightly upwards, they are much harder to bend out of their 

 plane, which is the direction in which they have to encoun- 

 ter the impulse and pressure of the air, and in which their 

 strength is wanted. It is also to be observed, that when two 

 threads, separated by accident or force, are brought together 

 again, they immediately reclasp. Draw your finger round 

 the feather which is against the grain, and you break, pro- 

 bably, the junction of some of the contiguous threads ; draw 

 your finger up the feather, and you restore all things to their 

 former state. It is no common mechanism by which this 

 contrivance is eflected ! The threads or laminae above men- 

 tioned are interlaced with one another ; and the interlacing 

 is performed by means of a vast number of fibres or teeth 

 which the threads shoot forth on each side, and which hook 

 and grapple together. Fifty of these fibres have been count- 

 ed in one twentieth of an itich. They are crooked, but 

 curved after a different manner : for those which proceed 

 from the thread on the side towards the extremity of the 

 feather are longer, more flexible, and bent downward ; 

 whereas those which proceed from the side toward the be- 

 ginning or quill-end of the feather, are shorter, firmer, and 

 turned upward. When two laminse, therefore, are pressed 

 together, the crooked parts of the long fibres fall into the 

 cavity made by the crooked parts of the others ; just as the 

 latch which is fastened to a door, enters into the cavity of 

 the catch fixed to the door-post, and there hooking itself 

 fast<nis the door i Dr. Paley. 



