"The sheath for making thunder ought to be short and large, and half filled with the aforesaid powder, and well bound in every direction with an iron band.
"Note. That in every sheath a small aperture is to be made, in order that it may be ignited by the match when applied, which match is made slender at the extremities, but in the middle large and filled with the aforesaid powder."
Another receipt of Marcus for Greek fire is as follows:—
"Greek fire is made in the following manner. Take pure sulphur, tartar, sarcocole, (a kind of resin,) pitch, fused saltpetre, and oil of petroleum. Boil them well together. Dip tow in the mixture, and set fire to it. This fire cannot be extinguished but with vinegar or sand."
The close analogy, or rather the identity, of these compositions with gunpowder as at present made, requires no comment. The more important question is the date at which this work was written. This is a matter of great doubt. Messrs Reinaud and Favé, from the fact that the receipt for the preparation of saltpetre to be found in this same book of Marcus is much more imperfect than that in the Arabian MSS., place the date of his book earlier than the thirteenth century. Again, Geber, an oriental writer, the date of whose life is doubtful, but whom our authors fix at the eighth century, has described the preparation of a salt which has been translated nitre, but which our authors consider to have been a sesqui-carbonate of soda, natron, not nitrum. They thence conclude that nitre was unknown to Geber, and thus, because it was known to Marcus, that he lived subsequently; and for this reason they place Marcus between the ninth and twelfth century.
We have seldom seen an instance of more loose deduction than this. It is required to find the date of Marcus. Geber, whose date is unknown, is set down, upon rather weak data, as of the eighth century. Geber's translator is corrected to prove that Geber did not know saltpetre. Hassan Alrammah, an Arabian, is considered as more recent than Marcus, a Greek, because his process for saltpetre is somewhat more perfect; and from the cumulative effect of these data, each of which is very insufficiently established, and which, if established, only go to prove differences in the degrees of perfection of their respective receipts, the date of Marcus is fixed: this certainly is pushing incertum per incertius very far. We fear that if no more accurate information be brought to bear on it, the epoch of Marcus Græcus will be a subject of as much controversy as ever.
The paragraph in the treatises De Mirabilibus of Albert the Great is so identical with that of Marcus Græcus, that there can be no doubt of its being copied from it, or derived from the same source, and is a strong additional instance of the general progress of inventions. A received publication calls attention to a fact already disclosed but forgotten, the knowledge acquired by the world since is brought to bear on the old fact; and a consequent improvement results.
Roger Bacon, to whom the invention or knowledge of gunpowder has been attributed by some, would stand a very poor chance among the men of science of the present day: it is not now the man who conjectures a possibility, but he who demonstrates a fact, that is hailed as the discoverer.
The following series of possibilities are curiously interesting, both from their partial subsequent realization, and from the simple credulity with which Bacon gives us that which he had known "a wise man explicitly excogitate."
"Instruments of navigation can be made, men being the propelling agents, that the largest river and sea barks can be borne along (one man only managing them) with greater speed than if they were full of navigators. Carriages can also be constructed which may be moved without animals, with an inestimable impetus; so that one would think that they were the armed chariots with which they fought in ancient times. Instruments for flying can also be made, so that a man sitting in the centre of the machine, and turning an engine, by which artificial wings may strike the air in the manner of a bird flying. An instrument also can be made, small in magnitude, for elevating and lowering almost infinite weights, than which nothing is more useful in mischances, for by an instrument of the length of three fingers, and of the same breadth or less, a man may extract himself and companions from all danger of prison, and elevate and lower them. An instrument can also be made by which one man may draw to himself a thousand men, by force and against their will. Instruments for walking on the sea can also be made, and in rivers to the bottom without corporal peril. For Alexander the Great used them that he might see the secrets of the sea, according to the relation of Ethicus the astronomer.