The<unk>  system (also known as the Birmingham Wire<unk>  is used in medicine to measure the diameter of hypodermic needles, catheters, and suture wires. It was originally developed in early 19th-century England for use in wire manufacture, and it began appearing in a medical setting in the early 20th century.
The<unk>  system was the first wire<unk>  recognized as a standard by any country when Great Britain adopted it in 1884. Each<unk>  increment roughly correlates to multiples of .01 inches, but the system is not truly linear, as can be seen in the Needle<unk>  comparison chart. Also, the needle<unk>  is inversely proportional to its diameter, so the larger the<unk>  number, the narrower the diameter.
Another common<unk>  system is the French catheter scale.
A common approximation used for medical needles is diameter (in inches) is equal to the reciprocal of the<unk> .
Needle wire<unk>  was derived from the<unk> .
Stubs iron wire gauge
Guidewire iron man
French catheter scale
X-ray image intensifier
Cubic meter
Needle gauge comparison chart
Flight nurse badge
Patch Adams