WONDERS OF A FEATHER
1.EVERY single feather is a mechanical wonder.If we look at the quill，we find properties not easily brought together，strength and lightness.I know few things more remarkable，than the strength and lightness of the very pen with which I am now writing.If we cast our eye toward the upper part of the stem，we see a material made for the purpose，used in no other class of animals，and in no other part of birds；tough，light，pliant，elastic.The pith，also，which feeds the feathers，is neither bone，flesh，membrane，nor tendon.
2.But the most artificial part of the feather is the beard，or，as it is sometimes called，the vane，which we usually 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 perpendicular to its plane，than when rubbed either up or down in the line of the stem.He will soon discover，that the threads of which these beards are composed，are flat，and placed with their flat sides toward 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 upward，they are much harder to bend out of their plane，which is the direction in which they have to encounter the impulse and pressure of the air，and in which their strength is wanted.
3.It is also to be observed，that when two threads，separated by accident or force，are brought together again，they immediatelyreclasp.Draw your finger down the feather which is against the grain，and you break，probably，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 effected.The threads or lamin？above mentioned，are interlaced with one another，and the interlacing is performed by means of a vast number of fibers or teeth，which the threads shoot forth on each side，and which hook and grapple together.
4.Fifty of these fibers have been counted in one twentieth of an inch.They are crooked，but curved after a different manner：for those which proceed from the thread on the side toward the extremity，are longer，more flexible，and bent downward；whereas，those which proceed from the side toward the beginning or quill-end of the feather，are shorter，firmer，and turned upward.When two lamin？，therefore，are pressed together，the crooked parts of the long fibers 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，fastens the door.
中文阅读
1.每一根羽毛都是机械上的奇迹。如果我们看看尾羽，就会发现它不容易聚拢，具有强度大并且质量轻的特点。除此之外，我从自己所用的羽毛笔上注意到了几个显著的特点。如果我们把目光集中在上半部分的笔杆上的话，就会发现其所用的材料是翮羽，而不是鸟其他部位的毛或者是其他动物的毛。这部分毛坚韧、质量轻、易弯曲，且富有弹性。而笔的木髓部分填充的也是羽毛，而不是骨头、肉、隔膜或是筋腱什么的。
2.然而羽毛上最不自然的部分就是颌毛，有时候我们也称之为翈的部分。制作羽毛笔的时候，我们通常会从一端，或者两端把颌毛扯下来。扯下来的这部分被称为线、单纤维或者条。这时，一个细心的观察者所注意的第一个问题就是：当颌毛垂直压在平面上时与被压成扁平状，而且被压平的毛不是朝杆上就是朝杆下的时候相比，强度要大多少。他很快就会发现，构成颌毛的单纤维是平的，每个平面都相对而置。这意味着，它们很容易倒向彼此，就像一个人轻轻竖起一根手指一样，单纤维在平面上弯曲更难，而这正是单纤维要克服在空气中遭遇的冲力和压力的方向，这样的强度正是羽毛笔所需要的。
3.细心的观察者还会发现，如果两条单纤维由于意外或者被强制分开，把它们再放在一起的时候，它们能够马上重新扣住。用一根手指逆向拨拉一根羽毛，你可能会折断两个临近单纤维的交接处；你再用手指顺向拨拉一根羽毛，一切又会恢复原状。这个过程不是一个正常的机械运动起作用的过程。上文提到的这些线或者说单纤维相互交织在一起。单纤维向四面八方伸展，这个交织网就是由大量更为细小的纤维和锯齿相互勾连缠扭在一起而形成的。
4.每二十分之一英寸有五十条这样的小纤维，它们弯曲着，但弯曲的样子并不一样。从一侧向末端延展的那些小单纤维通常比较长，柔韧性好，很容易朝下弯曲；从一侧向顶端或者尾羽延展的小单纤维通常比较短小、牢固，且向上弯曲。因此，当两条纤维被压在一起时，长的一端就会凹进另一条凹陷后所形成的弧内。这就好像插销的原理，插销的一头插入门上固定的门闩里，自动扣紧后把门锁上。