THE METRIC SYSTEM \& 





LIBRARY. 





■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 



TCTir w PTWB wftu f Centimeter (cm.), o.oi Meter; Millimeter (mm.), o.ooi Meter: 



THiJf^H < Micron(U), o.ooi Millimeter; theMicron is the unitin Micrometry(§i82). 



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



the gram for f Milligram (mg.), o.ooi Gram. 

 weight . . ( Kilogram, iooo Grams, used for ordinary masses, like groceries, etc. 



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

 capacity . \ rect form, Milliliter. 



Divisions of the Units are indicated by the I,atin prefixes ; deci, o.l ; cenii, o.oi ; Milli, 

 o.ooi ; Micro, one millionth (o.oooooi) of any unit. 



Multiples are designated by the Greek prefixes : deka, lo times ; hecto,ioo times ; kilo, iooo 

 times ; myria, 10,000 times ; Mega, one million (1,000,000) times any unit. 



TABLE OF METRIC AND ENGLISH MEASURES 



Meter (Unit of length)=ioo centimeters ; 1 ,000 millimeters ; 1 ,000,000 microtfs 



(u) 39.3704 inches : 3.2808 feet ; 1.0936 yards. 

 Centimeter (cm.)=io millimeters ; 10,000 microns (fi) 0.01 meter; 0.3937 (|) 



inch. 

 Millimeter (mm. )=i, 000 microns (u); 0.1 cm.; o.ooimeter; 0.03937 (-^) inch. 

 Micron (/a) (Unit of measure in micrometry (§182)— 0.001 millimeter; one 



millionth of a meter ; 0.00003937 (^5^5) inch. 

 Yard=3 feet ; 36 inches ; 0.91439 meter ; 91.4399 centimeters. 

 Foot= 12 inches ; 30.4799 centimeters ; 304.799 millimeters. 

 Inch= T V foot ; ^3 yard; 25.3999 millimeters (2.54 centimeters). 

 Liter (Unit of capacity)=i,ooo cubic centimeters (milliliters); (1 quart — . ) 

 Cubic centimeter=o.ooi liter (milliliter); (^ cub. inch.) 

 Fluid ounce (8 fluidrachms) =29.574 cubic centimeters (30 cc. — ). 

 Gram (Unit of weight )=i cc. of water; 15.432 grains. 

 Kilogram=[,ooo grams ; 2.2046 (2A) lbs. avoirdupois. 



Ounce avoirdupois=437i .grains ; 28. 3 49 grams. \ approx. 



Ounce Troy or apothecanes=48o grains ; 31.103 grams j J = ' " 



TEMPERATURE 



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

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



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

 reduce 50° Fahrenheit to Centigrade, (F.=5o°, and (50 — 32°)Xf=io C. ; or 

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

 72°XI= -40 C. 



Address of American Opticians : For the price of microscopesand 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 & lyOtnb Optical Co , Rochester, New York 



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



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



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



E- Leitz 30 East 18th St., New York 



Edward Pennock 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 YorV^^V^- 



Joseph Zentmayer .226-228 South 15th St., Philadelphia, "P/fc^ 



Besides the names here given, nearly every large city has one or more dealers in mij(f 

 scopes and microscope supplies. 



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