254 HOW TO SEE WITH THE MICROSCOPE. 



THESE FIGURES DENOTING THE NUMBER OF LINES IN .001 

 OF AN ENGLISH INCH. 



As a matter of convenience to those having the cele- 

 brated Nobert 19 band test plate, we present the fol- 

 lowing tabulated values of the rulings. The first 

 column contains the value in Paris lines. The second 

 the number c f lines in .001 of an English inch, as ruled 

 in the several bands. 



NUMBER. PARIS LINES. IN .100 ENO. IN. 

 1 1,000 11.26 



2 1,500 16.89 



3 2,000 22.52 



4 2,500 28.13 



5 3,000 33.78 



6 3,500 39.41 



7 4,000 45.04 



8 4,500.... 50.67 



9 5,000 56.30 



10 5,f>00 61.93 



11 6.000 67.56 



12 6.500 73.19 



13 7.000 78.82 



14 7,500 84.45 



15 8,000 90.08 



16 8,500 95.71 



17 3,000 101.34 



18 9,500 106.97 



19 10,000 112.60 



Returning now to our original list of diatom mounts 

 we proceed to give such a description of the same as 

 will enable the student to approach them intelligently, 

 iind without undue loss or waste of time. The first two 

 slides are pretty much the same thing, both contain 



