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LIBRARY. 



THE METRIC SYSTEM \& ^ £■ 



S, 



10 CENTIMETER RULE 



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



UNITS. The most commonly used divisions and multiples 



'_ „„___ _„„ ( Centimeter (cm.), o.oi Meter; Millimeter (mm.), o.ooi Meter: 



isiir™ roR) Micron(U-), o.ooi Millimeter; the Micron is the unit in Micrometry (§182). 



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



the gram for f Milligram (tag.), 0.001 Gram. 

 weight . . \ Kilogram, 1000 Grams, used for ordinary masses, like groceries, etc. 



the liter for f Cubic Centimeter (cc), 0.001 loiter. This is more common than the cor- 

 capacity . X rect form, Milliliter. 



Divisions of the Units are indicated by the I^atin prefixes ; deci, 0.1 ; centi, 0.01 ; Milli^^ 

 0.001 ; Micro, one millionth (o.oooooil of niw unit -~~- 



Multiples are de 

 times ; myria, 10,001 



TAB 



Meter (Unit of 1 



(#) 39-3704i 

 Centimeter (cm. 



inch. 

 Millimeter (mm. 

 Micron (/u) (Uni 



millionth of 

 Yard=3 feet ; 36 

 Foot=t2 inches ; 

 Inch= T 1 j foot ; 3- 1 

 Liter (Unit of ca 

 Cubic centimeter 

 Fluid ounce (8 fl 

 Gram (Unit of w 

 Kilogram= i ,000 

 Ounce avoirdupoi 



Ounce Troy or ap 



TEMPERATURE 



To change Centigrade to Fahrenheit; (C. Xf)+3 2 =F'. For example, to 

 find the equivalent of 10° Centigrade, C.=io°Xf+32=5o° F. 



To change Fahrenheit to Cenrigrade ; (F. — 32°) Xf=C. For example, to 

 reduce 50 Fahrenheit to Centigrade, (F.=so°, and (50° — 32°)Xf=io C. ; or 

 — 40° Fahrenheit to Centigrade, F.= — 40° ( — 40 — 32°)= — 72°, whence — 

 7 2°X!= -40 C. 



Address of American Opticians: For the price of microscopes and microscopical supplies 

 the student is advised to obtain a catalog of one or more of the opticians. Nearly all of them 

 import foreign apparatus. For foreign opticians see the table of tube-length, p. 18. 



The Bausch & I,omb Optical Co , — - - Rochester, New York 



James T. Dougherty .*. 409-411 "West 59th St., New York 



Fyimer & Amend __ 205-211 3d Ave., New York 



The Gundlach-Manhattan Optical Company Rochester, N. Y. 



E. Iyeitz__. _ __ 30 East i8th St., New York 



Edward Pen nock 3609 Woodland Ave., Philadelphia, Pa 



A. B. Porter 324 Dearborn St., Chicago 



Queen & Company ,. _-ioio Chestnut St., Philadelphia. Pa. 



Spencer I<ens Company 367-373 Seventh St., Buffalo, N. Y. 



Williams, Brown & Earle 918 Chestnut St., Philadelphia, Pa. ^^ 



Voigtl&nder und Sohn, A. G 225 Fifth Ave., New York/^^V- 



Joseph Zentmayer - .226-228 South 15th St., Philadelphia, Srf%* 



Besides the names here given, nearly every large city has one or more dealers in mi£ 

 scopes and microscope supplies. 



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