Without entering into the critical discussions which the vagueness of the historical records of these periods might tempt, we can scarcely be far wrong in setting down the general introduction of gunpowder during the first half of the fourteenth century, although any attempt to specify, from existing data, the exact date of its invention, would be vain. With regard to its connexion with Greek fire, we may sum up by stating, that during different periods, extending from the eighth to the fourteenth century, combustible matters, in which saltpetre was one ingredient, have been used; and that the term Greek fire has been, at various times within this period, applied to them. Although it does not necessarily follow that the Greek fire alluded to in the more recent works was identical with the Greek fire of an earlier period, yet the probability is strong that there was at least a striking analogy in effect, or the name would not have been used. There is, moreover, some internal evidence of community of origin in these various receipts, when we find that in different parts of the world, in China, in Arabia, and Greece, one general characteristic ingredient is present, viz., nitre; when also the history and progress of chemistry have taught us that no substance, other than nitre or a salt of nitric acid, has ever been, or is now known, which would produce similar effects, (for the comparatively recent discovery of the chlorates would produce effects of detonation by friction or percussion, of which we find no records,) there can, we think, be little doubt that Greek fire was of the same chemical character as gunpowder; that it passed by a transition, which may have been in particular cases more or less sudden, but which upon the whole was gradual, into gunpowder; and that the history of the progress of one of these manufactures is, in fact, the history of the progress of the other. In this history there are still many gaps to be filled up, many errors to be rectified. The book of Messrs Reinaud and Favé, though somewhat inartificially arranged, has given to the public much valuable information; but there is still room for an elaborate and well-digested treatise on the subject, in which the whole progress of pyrotechnic invention may be arranged in chronological order, and more lucidly expounded than are antiquarian matters in general. This is a task, however, which few, if any, are capable of undertaking, as it requires for its successful execution a combination of extensive antiquarian, chemical, and philological acquirements. In the mean time, our authors may say, and we say with them, "Si quid novisti rectius istis, Candidus imperti; si non, his utere mecum." HOW TO BUILD A HOUSE AND LIVE IN IT.