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