CH. F] 



DRA WING WITH THE MICROSCOPE 



133 



ing is then easier than to trace the outlines of the object. See also Ch. 

 VIII. 



REFERENCES 



Beale, 31, 355 ; Behrens, Kossel and Schiefferdecker, 77 ; Carpenter-Dallinger, 

 278 ; Van Heurck, 91 ; American Naturalist, 1886, p. 1071, 1887, pp. 1040-1043; 

 Amer. Monthly Micr. Jour., 1888, p. 103, 1890, p. 94 ; Jour. Roy. Micr. Soc., iSSi, 

 p. 819, 1882, p. 402, 1883, pp. 283, 560, 1884, p. 115, 1886, p. 516, 1888, pp. 113, 809, 

 798; Zeit. wiss. Mikroskopie, 1884, pp. 1-21, 1889, p. 367, 1893, pp. 289-295. 

 Here is described an excellent apparatus made by Winkel. Consult also the latest 

 catalogs of the opticians. 



1O CENTIMETER RULE 



The upper edge is in millimeters, the lower in centimeters, and half centimeters. 



THE METRIC SYSTEM 



UNITS. The most commonly used divisions and multiples. 



. (Centimeter (c.m.), i-iooth Meter ; Millimeter (m.m.), i-ioooth Meter: Micron 

 iR < (,x ). i-ioooth Millimeter ; the Micron is the unit in Micrometry & 166). 



LENGTH. 



( Kilometer, 1000 Meters ; used in measuring roads and other long distances. 



THE GRAM FOR \ Milligram (m.g.), i-ioooth Gram. 

 WEIGHT. . . > Kilogram, 1000 Grams, used for ordinary masses, like groceries, etc. 



THE LITER FOR i Cubic Centimeter (c.c. ), i-ioooth Liter. This is more common than the correct 

 CAPACITY. . \ form, Milliliter. 



Divisions of the Units are indicated by the Latin prefixes : deci, i-ioth ; centi, i-iooth ; Milli, 

 i-ioooth ; Micro, i-i,ooo,oooth of any unit. 



Multiples are designated by Greek prefixes : deka, 10 times ; hecto, 100 times ; kilo^ 1000 times 

 myria, 10,000 times ; Mega, 1,000,000 times any unit. 



