Gauges made at Crewe and used for the Manufacture of Graze-Fuses.
Reversible Mechanical Tapping Machine for Fuse Caps. Designed at Crewe (cp. [p. 81]).
[To face p. 78.
The graze-fuse itself is an intricate and cleverly thought-out little piece of mechanism, demanding a degree of accuracy in machining such as one might reasonably have assumed would suffice to baffle even the most knowing and perspicacious little minds attributable to the fair sex. The requisite delicacy of touch may perhaps be exemplified by the fact that the pellet plug flash-hole must be drilled dead-true to a depth of almost an inch with a drill no bigger than ·062, or 1/16 of an inch.
Mr. Lloyd George, when addressing the House of Commons in June, 1915, in his capacity of Minister of Munitions, held up a fuse for members to see. "This," he said, "is one of the greatest difficulties of all in the turning-out of shells. It is one of the most intricate and beautiful pieces of machinery—before it explodes, (laughter). It indeed is supposed to be simple, but it takes 100 different gauges to turn it out."
It was not, however, quite so much a question of the number of gauges required (considerable though the above-quoted figure may sound to those uninitiated in the art of fuse-making) as of the minuteness of the limits or tolerances allowed in the manufacture of these gauges.
Some reference to, or explanation of, gauge-making will be found on a later page, so that it may perhaps here be sufficient to remark en passant that whereas in the case of shell-body gauging, tolerances ran into fractions approximating 10/1000 parts of an inch, those of fuse-gauging were of an infinitely more exacting nature, being measured in fractions so minute as 3/1000 parts of an inch.