Sir Joseph Whitworth of Manchester, England, patented this Pattern I, Sub-pattern
I projectile on April 23, 1855, Great Britain patent #903. His patent states,
"Projectiles [are] made in a spirally shaped form, so as to fit exactly the interior
of a piece of ordnance or fire-arm made of a corresponding form, thereby enabling harder
metals to be used, economising the force hitherto expended in pressing the projectile into
rifle grooves, and diminishing the loss by windage and friction." No battlefield
recoveries of this pictured specimen are known to the authors. The use of this Whitworth
sub-pattern during the American Civil War is unlikely. Note the non-tapered base which was
felt to contribute to an unstable flight. As a result, the base in other Whitworth
sub-patterns were tapered to correct this defect.
