80 
MINUTES OF PROCEEDINGS OF 
The shape of the projections on the ball is regulated by the following 
considerations : It is desirable that it should be such as to permit of 
the ball readily freeing itself, due regard being paid to the support of the 
ball between the plugs. Now in the case of the lower projection, the 
present conical form is that which permits most readily of the liberation of 
the ball, and at the same time affords a sufficient hold; in the case of the 
upper projection, however, more hold is requisite, or the ball might become 
freed from the steady plug under the shock of discharge, whence premature 
explosion might result; this projection is therefore made cylindrical. 
Pettman's Land Service Fuzes can be used with all those Common 
Spherical Shells which have a cross cut upon the plug} 
(2) Pettman’s Sea Service Percussion Fuze 3 (Figs. 8,4) differs from 
the L.S. Pettman fuze principally in an arrangement by which the sensitive¬ 
ness of the fuze is so exactly regulated as to bring it within the limits 
prescribed for naval service, viz. that the fuze shall not explode when 
striking water with a high velocity, while it shall explode on striking a 
ship’s side or hard substance with a low velocity. 1 2 3 
PETTMAN’S SEA SERVICE PERCUSSION FUZE. 
Fig. 3. Full size. Fig. 4. 
This arrangement consists 1st, in placing immediately over the detonating 
composition on the ball two hemispherical cups of thin sheet copper, 4 the 
1 All common shells are now prepared to receive Pettman’s fuze; but the existing stores of common 
shells which have not the cross cut upon the plug and which consequently will not receive the fuzes, 
have probably not yet all been converted for their reception. 
2 Approved 2nd August, 18G2. W. O. C. 793, par. 610. 
3 It is sometimes considered that the sensitiveness of the sea service fuze is less than that of the 
land service fuze, this however can hardly be said of the case; indeed, where the direction of striking 
is sideways the sea service fuze is probably (owing to the enlargement of the interior) the more 
sensitive of the two. But the difference consists, as stated in the text, in the sensitiveness of the sea 
service fuze being exactly regulated and brought within certain limits, whereas the sensitiveness 
of the L.S. fuze is not so regulated or considered. 
4 The copper is rolled down tp •008 // , The weight of these cups is limited to from 5-£ to 6| grs, 
