THE ROYAL ARTILLERY INSTITUTION. 
429 
supersede the 7|-seconds fuze for these latter shell,* * * § It is available for 
times of flight from 1 to 10 seconds, f 
2. The 20 -seconds fuze for M.I. Ordnance% resembles in part the 
9-seconds fuze for M.L. ordnance, and in part a mortar fuze. 
Fig. 2. 
J ! V22S>> ! I 
; W7-** ! 
'•*-66+ 7-si 
It has, that is to say, the metal plug in the head, the escape holes, 
the priming, and copper and tape bands round the head, and the paper 
lining, which are characteristic of the 9-seconds fuze, while in respect of 
having only one row of side holes disposed spirally, and of having no 
powder channels, its construction is that of a mortar fuze. 
In two respects the fuze differs from both those which it generally 
resembles. It contains four inches of faze composition^ and a hole is bored 
transversely through the fuze immediately below the composition for the 
reception of a pellet of mealed powder pierced like a tube. The ends of the 
hole are protected by discs of thin paper secured with shellac varnish. 
Notation of the side holes is as in the large mortar fuze from two inches 
downwards; but each hole is marked, in lengths of inches. 
."Preparation and action. The preparation of this fuze is the same as that 
of the mortar fuze[| in so far as the boring is concerned; it is uncapped in 
the same way as the 9-seconds fuze. 
* W.O. Letter, 5th July, 1866, 75/12/2852, and W.O.C. 10 (new series), § 1236. 
f The fuze is called a 9-seconds fuze because this is its mean time of burning in rifled shell, in 
which notwithstanding the plug a certain acceleration of burning does take place. In a spherical 
shell, however, the fuze will burn the full time due to 2 inches of composition, i.e. 10 seconds. 
$ Approved, 7/6/’67. W.O. Letter 3/7/’67 
§ There is *1" of mealed powder on the top of the composition bored into to facilitate ignition. 
But as the hole all but extends through the mealed powder, this pellet does not appreciably increase 
the time of burning of the fuze. 
|| But owing to the side holes being bored deeper is not nearly so slow or laborious. 
