470 NATURE'S TEACHINGS. 



instead of having the wheel solid, to fill up its interior with 

 spokes, thus gaining lightness and strength at the same time. 



Of all locomotive wheels, I suppose that the modern Bicycle 

 affords the best example. The driving wheel is larger than 

 the hind wheel of an ordinary coach, and yet the spokes are 

 not nearly so thick as the porcupine quill with which this 

 account is written. 



If we look at the ancient sculptures and paintings of Egypt 

 and Assyria, as preserved in the British Museum, we shall see 

 that either kind of wheel was used according to the work 

 which it had to do. The solid, uneven, squeaking, wooden 

 wheel was devoted to agriculture, while the light, spoked wheel 

 was sacred either to warfare or hunting. 



Let us hope that in the two latter cases some modicum of 

 grease might have been used, as the outcries of tortured and 

 unlubricated machinery are enough to drive away all wild 

 beasts which come within the range of its complaints, while the 

 nervous system of hunter or warrior must have been seriously 

 damaged by it. 



EVEN in such a structure as the spoked Wheel, Nature has 

 anticipated Man. 



My readers may remember that, when treating of nautical 

 matters, I mentioned the singular anchor-shaped spicules that 

 are found upon one of the sea-slugs, called Synapta. 



There is another group of these creatures inhabiting the 

 Mediterranean, in which the skin-spicules take a different form. 

 Like those of the Synapta, they are too small and translucent 

 to be seen without the aid of the microscope and carefully 

 adjusted light. But, just as the spicules of the Synapta 

 resemble the ancient anchor, so do those of the Chirodota 

 resemble the ancient wheel, the similitude being in both cases 

 absolutely startling. 



Not only that, but, as all readers must be aware, if they 

 have studied practical mechanics, there are many machines 

 which are toothed on the inner, and not the outer, side of 

 the circumference. Here, in the Chirodota, the inner toothing 

 is manifest. 



What purpose it serves we know not. The Chirodota's 

 wheels (of which there are thousands) never revolve, neither 





