The need of an explosive projectile to blow up earthworks, &c., was more and more felt as time rolled on, and the use of such missiles was clearly impossible with such igniters so placed. But the best way of mending matters was by no means so clear. If an explosive shell was placed in the bore with an igniter of soft, caseless composition next the cartridge, there was in the great majority of rounds a burst in the bore. If the shell was reversed, with the igniter towards the face of the piece, either the composition did not ignite and the shell was blind, or the soft composition set back into the shell from the shock of the explosion[604] and again there was a burst in the bore. Furthermore, in firing against works it was before all things necessary that the shell should enter the revetment, &c., before it exploded, and it was extremely difficult in practice to put into the shell the exact amount of composition that would burn just longer than the time of flight. To prevent the gases of the explosion from forcing their way into the interior of the shell, it was necessary to have the fuze-hole towards the muzzle when the shell was home. To prevent the soft composition from setting back, and to ensure that it was sufficient in quantity to burn longer than the time of flight, a fuze-case was necessary. To ensure the ignition of the fuze (in its new position) it was necessary to light it from the muzzle just before the piece was fired, and this condition restricted the use of explosive shell for centuries to mortars and (afterwards) howitzers. No one would have dared to thrust a lit match down the bore of a gun which had been loaded with loose powder by means of a ladle, and cartridges were not in general use when the question of explosive shell arose. Bourne says in 1587: “It is a great deal better for to charge a peace in time of service with a cartredge than with a ladell,”[605] and he presently proceeds to give his reasons for thinking so at great length.[606] In the beginning of the following century, Diego Ufano only allows the use of cartridges when a ladle is not at hand. Such were the steps of the evolution of the fuze, as partially explained by Hanzelet and Thybovrel in their _Receuil de plusieurs Machines Militaires_, published in 1620: “Le souspirail de l’amorce (the funnel of the priming = the fuze-case) est long ... et creux.... Ainsi ce canal éstant emply de composition lente, il ne permet que le feu se prenne qu’il nait (n’ait) lentement consumé la matière mise audit canal, et par ce moyen le feu ne peut toucher la poudre grainée (the bursting charge) qu’il ne soit arrivé jusques au fond de la ditte grenade. Cela sert pour avoir loisir de la jetter à la main, ou de l’allumer et la mettre dans le mortier ou canon” (l. iv. c. 6).