209 



Table fok the Conversion of English and Metrical Linear 

 Measures ; Yard at 62° F, and Metre at 0° C. 



As the measurements of many microscopical objects are given in 

 fractions of an inch in English literature, and in metrical measure in 

 foreign works, the above table has been drawn up to facilitate com- 

 parison. Its use is obvious. Examples: l/7th inch = 3-63 mm., l/58th inch 

 = 438 fx, or -438 mm. For fractions smaller than l/250th inch that portion 

 of the table between the figures 26 and 99 may be used by cutting off 

 the last figure for hundredths, and the two last figures for thousandths. 

 Examples : l/270th inch = 94-1 fi, or -0941 mm. ; l/7900th inch = 3*22 /x, 

 or -00322 mm. When that portion of the table between the figures 100 

 and 250 is used it is only necessary to cut off the last figure for thousandths, 

 and the two last figures for ten thousandths. Exami^les : l/1350th inch 

 = 18-8 M, or -0188 mm., l/16500th inch = 1-54 /^, or -00154 mm. The 

 conversion of millimetres into fractions of an inch is performed in the same 

 smanner; thus, 529 fi or -529 mm. = l/48th inch; 39-7 /* or •0397mm. 

 = l/640th inch ; 2-62 /^ or -00262 mm. = l/9700th inch ; 1-04 /x or -00104 

 mm. = l/24500th inch ; -977 fi or -000977 mm. = l/26000th inch, and 

 so on.— E. M. N- 



