90 



APPROXIMATE CONVERSION NUMBERS 

 FOR THE USE OF NATURALISTS. 



J. S. WOOD, 

 Xybor^, Deiunark. 



The reduction-tables at the end of Mr. Ridgway's book on ' Colour ' 

 are certainly very complete and useful, but a simpler method of 

 reduction for the several measures would have been very welcome to 

 many naturalists. I have myself often felt the want of such an 

 approximate method of reduction, and have for some time used a 

 table of my own working-out for that purpose. This table I take the 

 liberty of enclosing for publication. 



TO CONVERT 



English inches to millimeters 



multiply by 127 and divide by 5 



Millimeters to English inches 





5 



>» 



127 



Lines i^p.d.r.) to eighths of English inch 





32 





45 



Eighths of English inch to Lines (p.d.r.) 





45 



. 5 5 



32 



Lines to millimeters 



> 5 



115 



! 1 



51 



or a little more accurate 





69*5 



• 1 



30-8 



Millimeters to Lines 





51 



5» 



115 



or a little more accurate 



• J 



30-8 



J > 



69-5 



Swedish inches to English inches 



? 5 



37 



5 5 



38 



English inches to Swedish inches 



5 > 



38 



! 1 



37 



Leipsic inches to English inches... 





56 



3 ." 



52 



English inches to Leipsic inches... 



! 5 



52 



5 J 



56 



English inches to Danish inches... 



5> 



34 





35 



Danish inches to English inches... 





35 



J 5 



34 



Danish eighths of an inch to millimeters 





85 



5 5 



26 



Millimeters to Danish eighths of an inch 



J J 



26 



» > 



85 



Twentieths of English inch to millimeters 



J 5 



127 





100 



Millimeters to twentieths of English inch 



? 5 



100 





127 



Sixteenths of English inch to millimeters 





127 



5 J 



80 



Millimeters to sixteenths of English inch 





So 





127 



Twelfths of English inch to millimeters 



J J 



127 



5 5 



60 



Millimeters to twelfths of English inch 



5 5 



60 



5 > 



127 



Tenths cf English inch to millimeters ... 





127 





50 



Millimeters to tenths of English inch ... 



5 J 



50 



■> > 



127 



EXAMPLES. 



Reduce 5^ English inches to millimeters. 5j = 5'25 X i27 = 666"75-^5 = i33'35 millinieters. 

 Reduce 1440 lines (p.d.r.) to millimeters. i44oXii5 = i656o'o-f-5i = 3247'o nullimeters "J 



(rirst method) (_ Correct, 



Or ,, ,, ,. 1440 x69'5 = ioooSo'o-f-3o"S = 3249'3 millimeters ( 324S'48. 



(second method). / 

 Reduce 120 tenths of an English inch to millimeters. 1 20 X 127 = 1 524o-=-50=3O4"8 millimeters. 

 Reduce 240 twentieths ., .. 240 X 127 = 30480-1-100= 304'S millimeters. 

 Reduce 6 Swedish inches to millimeters. 6X37 = 222-^38 = 5 "894 English inches. 5"8947Xi27 

 = 748"6269-f-5 = i49"72538 millimeters. - 



Naturalist, 



