58 THE MICROSCOPE. Apr. 



IV.— FINISHING. 



1. Date as above. 



2. Place mount upon turn-table. 



3. Ring with shellac cement. 



4. Put aside for thorough drying. 



5. Place mount upon turn-table. 



6. With cut-edged needle cut away any irregularity in outer 

 edge of shellac ring. 



7. Cover with zinc- white cement. 



8. After about 5 minutes ring with any color of lacquer ce- 

 ment (King's) to suit taste. 



9. Put aside to set and dry. 



10. In about a week polish slide, put on labels, copying any 

 dates of importance you choose and remove date slips from 

 under side by wetting. 



11. Result: a beautiful slide. 



The Size of a Spider's Thread. — Leuwenhoek, the first 

 microscopist, wrote in 1685 as follows: 



I have often compared the size of the thread spun by full 

 grown spiders with a hair of my beard. I placed the thickest 

 part of the hair before the microscope and from the most accu- 

 rate judgment I could form, more than a hundred of such 

 threads placed side by side could not equal the diameter of one 

 such hair. If, then, we suppose such a hair to be of a round 

 form, it follows that 10,000 threads spun by the full grown spi- 

 der, when taken together will not be equal in substance to the 

 size of a single hair. 



To this, if we add that 400 young spiders, at the time when 

 they begin to spin their webs, are not larger than a full grown 

 one, and that each of these minute spiders possess the same or- 

 gans as the larger ones, it follows that the exceedingly small 

 threads spun by these little creatures must be still 400 times 

 glenderer; and, consequently, that 4,000,000 of these minute 

 spiders' threads cannot equal in substance the size of a single 

 hair. 



The British Association meeting for 1894 will be held in 

 August at Oxford, England and Lord Salisbury will preside, 

 A large attendance may be looked for. 



