364 PHOTOGRAPHIC FACTS AND FORMULAS 
10 per cent = 43.75 
5 per cent = 21.875 
65.625 gr. 
Required 16 oz. of 10 per cent solution, how many grains — | 
required: 4 
48 X 16 = 568 gr. / 
The following tables are sufficient to enable anyone to read- } 
ily convert the metric into the customary units, and are based 
on those published by the U. S. Bureau of Standards. 
Lengths. — 
Inches Centimeters Inches Centimeters 
0.3937 =] 1 = 2.5400 
0.7874 —=2 2 = 5.0800 
1.1811 = 3 3 = 7.6200 
1.5748 = 4 4 = 10.1600 
1.9685 = 5 5 = 12.7000 
2.3622 = 6 6 == 15.2400 
2.7559 = 7 rf = 17.7800 
3.1496 = § 8 = 20.3200 
3.5433 —=9 9 = 22.8600 
Areas.— 
Square Square Square Square 
Inches Centimeters Inches Centimeters 
0.1550 = |] 1 = 6.452 
0.3100 —2 2 = 12.903 
0.4650 = 3 3 == 19.355 
0.6200 —=4 . 4 = 25.807 
0.7750 = 5 5 == 32.258 
0.9300 = 6 6 = 38.710 
1.0850 =7 7 = 45.161 
1.2400 = 8 8 = 51.613 
1.3950 = 9 9 = 58.065 
= Ona 
Se Sse ee 
