The Berlin Firebook does not profess to give us an account of ammunition actually used in the field; it merely describes certain ammunition proposed for use by a fireworker, or inventor, and it adds his honest convictions of the way in which it would act if manufactured. The excerpts given by Herr von Romocki from the Firebook, in so far as they concern the projectile in question, are simply the specification and opinions of an inventor, and there are no grounds for supposing that his missile was ever made or ever tried. If these projectiles had been used with effect in the field, their inventor would surely have been the first to tell us of their success. There is nothing remarkable in the above conclusion: the inventor followed the custom of his age. The value of experiment generally, the absolute necessity for experiment in gunnery, was unknown or altogether underrated in the Middle Ages, and those fireworkers who may have suspected its importance had neither the money nor the opportunity to put their theory into practice. Would Sextus Julius Africanus and Marcus Græcus have bequeathed to us certain preposterous recipes, had they been at the pains and expense of making them and trying them? It was Roger Bacon who wrote: “Experimental science ignores abstract arguments; because, strong though they may be, their conclusions are not perfectly certain until verified by experiment.... In these studies experiment alone, not abstract reasoning, leads to certain conclusions.”[579] Yet even he, with his “everlasting lamps,” has not quite escaped the infection of the prevailing fashion: he never tried these lamps. Bourne has left us a whole book of “Inventions and Devices,” and at least one half of Boillot’s book is occupied by similar inventions; but neither of them makes the slightest suggestion that any one of his contrivances was ever made or ever tried. We may, then, discard the wholly unpractical proposal of the Berlin Firebook, and accept Valturio’s as the earliest incendiary cannon-shell of which we have any detailed account. _Carcasses._ Carcasses were invented in 1672 by a gunner in the service of Christopher van Galen, the fighting Prince Bishop of Munster.[580] They are mentioned in the _London Gazette_, 1980/1, 1684. They were originally oblong, in order to contain a large quantity of incendiary matter; but their flight was so erratic that it became necessary to make them spherical. Their thickness was at the same time so much reduced, in order to increase their internal capacity, that a large proportion broke up in the bore. To remedy this defect during the siege of Quebec, 1759, “the interval between the powder and the carcass was filled with turf,” an arrangement which “produced every desired effect.”[581] _Explosive Fireballs._ Explosive fireballs were simply hand-grenades, which, according to the classification of ammunition adopted here, have been already noticed, p. 169. _Explosive Shell._