Descriptive Number. Equivalents in parts of an inch. 7/0 0.500 6/0 464 5/0 432 4/0 400 3/0 372 2/0 348 0 324 1 300 2 276 3 252 4 232 5 212 6 192 7 176 8 160
 Descriptive Number. Equivalents in parts of an inch. 9 0.144 10 128 11 116 12 104 13 0.092 14 80 15 72 16 64 17 56 18 48 19 40 20 36 21 32 22 28 23 24
 Descriptive Number. Equivalents in parts of an inch. 24 0.022 25 20 26 18 27 0.0164 28 148 29 136 30 124 31 116 32 108 33 100 34 0.0092 35 84 36 76 37 68 38 60
 Descriptive Number. Equivalents in parts of an inch. 39 0.0052 40 48 41 44 42 40 43 36 44 32 45 28 46 24 47 20 48 16 49 12 50 0.0010

The Birmingham Wire Gauge, known also as the Birmingham Iron Wire Gauge, the Slieet Iron Gauge, and the Wire Gauge, was at one time used for sheet iron, steel, hoop iron, tubes, and wire, but is now reserved for the three latter, and is generally expressed by the initials BWG or WG. The following Table gives the thicknesses as carefully measured by Mr. Holtzapffel, and given in his Meclianical Manipulation. The mark 00000 is not shown in his list, but is frequently added : -

1 Extracted from Box On Heat.

 Mark or No. of Guage. Thickness in inches. 00000 0.500 0000 0.454 000 0.425 00 0.380 0 0.340 1 0.300 2 0.284 3 0.259 4 0.238 5 0.220 6 0.203
 Mark or No. of Gauge. Thickness in inches. 7 0.180 8 0.165 9 0.148 10 0.134 11 0.120 12 0.109 13 0.095 14 0.083 15 0..072 16 0.065 17 0.058
 Mark or No. of Gauge. Thickness in inches. 18 0.049 19 0.042 20 0.035 21 0.032 22 0.028 23 0.025 24 0.022 25 0.020 26 0.018 27 0.016 28 0.014
 Mark or No. of Gauge. Thickness in inches. 29 0.013 30 0.012 31 0.010 32 0.009 S3 0.008 34 0.007 35 0.005 36 0.004

"Although, this gage seems only to possess 40 terms, in reality not less than 60 sizes of wire are made, as intermediate sizes are in many cases added, and occasionally, though the sizes are retained, their numbers are variously altered."1