158 NATURE'S TEACHINGS. 



The chief parts in this machine are a hollow cylinder, a 

 piston, and a delivery tube. The cylinder ( is shown at A, and 

 when used is filled with melted lead. The piston, B, is then 

 forced upwards by hydraulic pressure, driving the lead through 

 the delivery tube. As it issues into the air it hardens, and 

 thus forms a solid rod of lead, c. This rod is then passed into 

 the next machine, where it is cut into regular lengths, and 

 these pieces are then placed in moulds, and forced into form 

 by enormous pressure. Were it not for this ingenious 

 machinery, the wonderful scores which are now made at long 

 distances would be impossible. 



Now let us compare Art with Nature, as seen on the left 

 hand of the illustration, which is a chart or plan of the spinning 

 apparatus of the Silkworm. 



"When I first saw the bullet-making machine at work, I at 

 once perceived that it was nothing more than a repetition in 

 metal of the beautiful mechanism which I had so often admired 

 in this insect. In order to show the close analogies of the two 

 objects, I have marked them with similar letters. 



A represents the upper part of the reservoir or vessel which 

 contains the silk in a liquid state. B B are the muscles which 

 contract the reservoir and force the liquid matter out. It will 

 be seen that both these vessels terminate in a delivery tube, 

 identical in office with that of the bullet-making machine. As 

 soon as the liquid silk passes into the air it is hardened, and 

 is formed into a silken rod, c, just as is the lead in the machine. 

 The only difference between the two, if it can be called a 

 difference, is, that in the silkworm the rod is double, whereas in 

 the machine it is single. The principle, however, is identical 

 in both cases. The webs of spiders, and the threads by which so 

 many caterpillars suspend themselves, and with which they 

 make their nests, are all formed on the same design, namely, 

 a reservoir containing a liquid which is squeezed through a 

 tube, and hardens when it comes in contact with the air. 



