328 QUARTZ FIBERS. 



which I shall be able to show only imperfectly, namely, the power of 

 insulating anything charged with electricity under conditions under 

 which in general insulation is impossible. You now see upon the screen 

 an electroscope, the leaves of which were charged at noon, and they 

 are still divergent, but not to a very great extent, because they have 

 suffered from unavoidable shaking during the day. The point to 

 which I especially wish to refer is this. In electroscopes and all elec- 

 trostatic apparatus one puts in a dish of sulphuric acid, (which is an 

 abomination,) in order to keep the atmosphere dry. I have in this 

 electroscope such a dish, but it is filled with water in order to keep the 

 atmosphere moist. Experiments carefully made, using the same box — 

 everything the same, except that in one case the insulating stem was 

 made of quartz and in the second case it was made of the best flint 

 glass well washed, of the same shape and size — show that if the 

 atmosphere is perfectly dry the electricity escapes from both at the 

 same rate ; but that if the atmosphere is perfectly moist the electricity 

 escapes from the leaves insulated by the clean washed flint glass 

 only too quickly; whereas, from the leaves insulated by the quartz the 

 rate is identically the same as it was in cither case when the atmos- 

 phere was perfectly dry. 



I have said that these fibers are uniform in diameter, and fine and 

 smooth and strong, and that they glisten with all the colors of the 

 spider web, but that they are far more brilliant. It was naturally 

 rather a curious point to note what a siiider would do if by Rwy chance 

 she should find herself on such a web; and now that I am dealing with 

 live and wild animals which can not possibly be trained, the conditions 

 are such as to render the success of an experiment entirely a matter of 

 chance. Ilowever, I propose to make use of the spider as a test of the 

 very great smoothness and slippeviness of one of these fibers. There 

 are here three little si)iders which have been good enough, since they 

 came to Leeds, to spin ui)on these little wooden frames their perfect 

 and beautiful geometrical webs. 1 have succeeded in placing one of 

 theise frames in the lantern without disturbing the spider, which you 

 can now see waiting upon her web. I must now, without disturbing 

 the peace of mind of the spider, carry her to a web of quartz; and 

 therefore it is necessary that the spider should be fortunate enough to 

 catch a fly. Now, instead of bringing a fly I will make an ordinary 

 tuning-fork buzz against the web. She immediately pounces upon the 

 imaginary fly, and thus I can without frightening her place her upon 

 the quartz fiber. Unfortunately this spider has slipped and has got 

 away, but with another I am more successful. I intended to show that 

 the small and common garden spider could not climb the quartz fiber, 

 but for some reason this spider is able to get up with difticult3^ How- 

 ever I shall not spend any more time upon this experiment. 



I shall now at once speak about the instrument which actually led 

 me to the invention of the process for making quartz fibers. This, 



