GLASS SPUN INTO THREADS. 107 



" I should not have thought it would be possible to spin 

 glass in that way," said John, " and certainly not to spin 

 it so even and true. I looked at a piece of it when I was 

 down there, and it was just as even in every part as a hair, 

 and very fine, and yet the man does not seern to take any 

 pains to make it so even." 



" It evens itself," said Lawrence. " There are one or 

 two very curious principles involved. There is one that 

 you will think is specially curious, if I can only explain it 

 so that you will understand it. You see that, the hotter 

 the glass is, the weaker it is, because it is more fluid ; while 

 the colder it is, the stronger and stiffer it is. Now, in draw- 

 ing out the glass, it gets cold and strong just in proportion 

 as it gets thin, and that holds it in the thin and slender 

 places, and prevents it getting thinner. 



"In other words," continued Lawrence, "just so fast as 

 any parts of the thread get thinner than the rest, they cool 

 at once, and become stronger, and that brings the force to 

 act upon the parts which are thicker, and, of course, more 

 soft, and they are drawn out until they are as thin as the 

 rest." 



The same principle operates on a larger scale in pulling 

 candy, and it is by the effect of it that it is so easy to make 

 the candy into sticks so uniform and even. 



Just at this moment a bell was rung, and there was ah 

 immediate movement among the audience toward a certain 

 door behind the place where Lawrence and John had been 

 sitting. They immediately rose and followed the multi- 

 tude, supposing that the bell was a summons to hear the 

 lecture on ghosts. There was a great crowding and jam- 

 ming in getting through the door, each one apparently be- 

 ing eager to obtain a good seat. 



Lawrence and John pressed onward with the crowd, 

 and, when they at last entered the room, they found that 



