318 



qUAllTZ FIHEKS. 



physicist's disposal bave until lately been simply limited by the behavior 

 ofsillc. A more perfect susi)eusion meaus still more perfect instruments, 

 and therefore advance in knowledge. 



It was in this way that some improvements that 1 was making' in an 

 instrument for measuring radiant heat came to a dead-lock about 2years 

 ago. I would not use silk, and I could not tind anything else that would 

 do. Spun glass even, was far too coarse for my purpose; it was a 

 thousand times too stiff. 



There is a material invented by Wollaston long ago, which however 

 I did not try because it is so easily broken. It is platinum wire whicli 

 has been drawn in silver, and finally separated by the action of nitric 

 acid. A specimen about the size of a single line of silk is now on the 

 screen, showing the silver coating at one end (Fig. 5). 



As nothing that I knew of could be obtained that would be of use to 

 me, I was driven to the necessity of trying by experiment to find some 

 new material. The result of these experiments was 

 the development of a process of almost ridiculous 

 simplicity which it may be of interest for me to show. 

 The apparatus consists of a small cross-bow, and 

 an arrow made of straw with a needle point. To 

 the tail of the arrow is attached a tine rod of quartz 

 which has been melted and drawn out in the oxy- 

 hydrogen jet. I have a piece of the same material 

 in my hand, and now after melting their ends and 

 Joining them together, an operation which produces 

 a beautiful and dazzling light, all I have to do is to 

 liberate the string of the bow by pulling the trigger 

 with one foot, and then if all is well a fiber will have 

 been drawn by the arrow, the existence of which can 

 be made evident by fastening to it a piece of stamp 

 l>aper. 



In this way threads can be produced of great 

 length, of almost any degree of fineness, of extraor- 

 dinary uniformity, and of enormous strength. I do 

 not believe, if any experimentalist had been prom- 

 ised by a good fairy that he mi^;ht have anything he 

 desired, that he would have ventured to ask for any 

 one thing with so many valuable properties as these 

 fibers possess. I hope in the course of this evening 

 to sliow that I am not exaggerating their merits. 

 \ In the first place, let me say something about the 



a degree of fineness to which they can be drawn. 

 There is now projected upon the screen a quartz 

 liber one five-thousaiulth of an inch in diameter (Fig. 

 ()). This is one whi(;h I had in constant use in an instrument loaded 

 with about 30 grains. It has a section only onr-sixth of that of a single 



Fig. 5. 



