i48 t^ATURAL THEOLOGY. 



far enough over the short ones, their crooked parts fall into 

 the cavitymade by the crooked parts of the others ; just as 

 the latch that is fastened to a door enters into the cavity of 

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

 fastens the door ; for it is properly in this manner that one 

 thread of a feather is fastened to the other. 



This admirable structure of the feather, which it is easy 

 to see with the microscope, succeeds perfectly for the use to 

 which nature has designed it ; which use was, not only that 

 the laminsB might be united, but that when one thread or 

 lamina has been separated from another by some external 

 violence, it might be reclasped with sufficient facility and 

 expedition.* 



In the ostrich, this apparatus of crotchets and fibres, of 

 hooks and teeth, is wanting ; and we see the consequence 

 of the want. The filaments hang loose and separate from 

 one another, forming only a kind of down ; which constitu- 

 tion of the feathers, however it may fit them for the flowing 

 honors of a lady's headdress, may be reckoned an imper- 

 fection in the bird, inasmuch as wings composed of these 

 feathers, although they may greatly assist it in running, do 

 not serve for flight. 



But under the present division of our subject, our busi- 

 ness ^dth feathers is as they are the covering of the bird. 

 And herein a singular circumstance occurs. In the small 

 order of birds which winter with us, from a snipe down- 

 wards, let the external color of the feathers be what it will 

 their Creator has universally given them a bed of Uaxk 

 down next their bodies. Black, we know, is the warmest 

 color ; and the purpose here is, to keep in the heat arising 

 from the heart and circulation of the blood. It is further 

 likewise remarkaHe, that this is not found in larger birds ; 

 for which there is also a reason. Small birds are much 

 more exposed to the cold than large ones, forasmuch as the)- 



* The above account is taken from Memoirs for a Natural History 

 of Animals, by the E,oyal Academy of Paris, published in 1701, p. 219 



