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551 



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THE METRIC SYSTEM 







10 6entImeiter rule 



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



UNITS. The most commonly used divisions and multiples. 



(Centimeter (era.), o.oi Meter; Millimeter (mm.), o.ooi Meter: Micron i/j.), 

 TI ? p "tL - o.ooi Millimeter ; the Micron is the unit in Micrometry (J 166). 



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

 THE GRAM FOR ( Milligram { mg.) , o.ooi Gram. 



"WEIGHT. . . / Kilogram, iooo Grams, used for ordinary masses, like groceries, etc. 

 the liter for J Cubic Centime ler ( cc. ), o.ooi Liter. This is more common than the correct 

 capacity. . \ form, Milliliter. 

 Divisions of the Units are indicated by the Latin prefixes : deci, o.i ; centi, o.oi ; Milli, 

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



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

 timse ; myria, 10,000 times ; Mega, one million (i,ooo,ooo) times any unit. 



TABLE OF METRIC AND ENGLISH MEASURES 



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

 39.3704 inches ; 3.2S08 feet ; 1.0936 yards. 



Centimeter (cm. )=io millimeters ; 10,000 microns (u) 0.01 meter ; 0.3937 (I) inch. 



Millimeter (mm.)=i,ooo microns (/') ; 0.1 cm. ; 0.001 meter ; 0.03937 (o- 1 -) inch. 



Micron (u) (Unit of measure in micrometry (§ i66)=o.ooi millimeter ; one mil- 

 lionth of a meter ; 0.00003937 ( rrimr) lncn - 



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



Foot=i 2 inches ; 30.4799 centimeters ; 304.799 millimeters. 



Inch^yV foot ; 3 l 6 yard ; 25.3999 millimeters (2.54 centimeters). 



Liter (Unit of capacity) = 1,000 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)= 1 cc. of water ; 15.432 grains. 



Kilogram=i, 000 grams ; 2.2046 (2^) lbs. avoirdupois. 



Ounce avoirdupois=437J- grains ; 28.349 grams. 1 ms 



Ounce Troy or apothecaries=4So grains ; 31.103 grams) J 5 • trf 



TEMPERATURE 

 To change Centigrade to Farenheit : (CX I) +32 =F. For example, to find 



the equivalent of io° Centigrade, C.= io°X f+ 3 2 = 5°° E. 



To change Farenheit to Centigrade : ( F. — 32 ) x | = C. For example to re- 

 duce 50 Farenheit to Centigrade, F.= 50°, and (50 — 32°)X § = IOC. ; or — 40 



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



= — 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 all institutions entitled to duty free importation, American microscopes 

 are sold at duty free rates. For the foreign opticians see the table of tube-length p. 14. Q 



The Bausch and Lomb Optical Co., New York, Rochester, and Chicago. 



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



The Franklin Laboratory Supply Co , Harcourt St., Boston, Mass. 



The Gundlach Optical Company, Rochester, N. Y. 



Wffl, Krafft (Representative of Leitz in America), 411 West 59th St., New York. 



Edward Pennock, , 3609 Woodland Ave., Philadelphia, Pa. 



Queeu & Company, 1010 Chestnut St., Philadelphia, Pa. 



Richards & Co., 12 East iSth St., New York, and 108 Lake St., Chicago, Ills. 



Spencer Lens Company, 367-373 Seventh St., Buffalo, N. Y- 



Williams, Brown & Earle, 91S Chestnut St., Philadelphia, Pa. 



G. S. Woolman (Queen & Co. in New York), 116 Fulton St., New York. 



Joseph Zentmayer, 226-22S South 15th St., Philadelphia, Pa. 



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

 and microscope supplies. 



