The practice of shoeing horses was introduced into England by William I. We are told that this monarch gave the city of Northampton as a fief to a certain person, one of his attendants, in consideration of his paying a certain sum yearly for the shoeing of horses. And it is also alleged, that Henry, or Hugh de Ferres, or de Ferrers, was the same person who held this fief on the above condition, and who was the ancestor of the family of that name, and who still bear six horse-shoes in their coat of arms. This was the person whom William entrusted to inspect his farriers. We should not omit to observe, that it is remarked, that horse-shoes have been found, with other riding furniture, in the graves of some of the old inhabitants of Germany, and also in those of the Vandals in the North of Europe. GUNPOWDER. The express period when _nitrum_ was first discovered is extremely uncertain; but that this nitrum is an alkaline salt, there is little difficulty in proving. It has, indeed, been conjectured that it was a component part of the _Greek fire_, invented about the year 678, which has been generally believed to be the origin of gunpowder. From the oldest prescriptions which have been found, and which is said to be that given by the Princess Anna Commena, in which, however, only resin, sulphur, and oil are mentioned, saltpetre does not appear. It is believed by an author very well qualified to form a judgment on the question, that the first certain account we have of saltpetre by that express name, occurs in the oldest account of the invention of gunpowder, which, according to him (Professor Beckmann) occurred in the thirteenth century. Dr. Rees, in his Cyclopedia, expressly says, about the year 1320; and that it was first used by the Venetians employed against the Genoese in 1380; also that it was first in Europe at a place now known as Chrogia, against Laurence de Medicis; and the last named authority adds, “That all Italy made complaint against it, as a contravention of the law of arms.” Dr. Rees gives the following recipe for its manufacture, without distinguishing the proportionate parts:--“A composition of nitre, sulphur, and charcoal, mixed together, and usually granulated.” He describes its effects by observing, that “it easily takes fire, and when fired, rarifies and expands with great vehemence by means of its elastic force;” also that “it may be made without _nitre_, by means of _marine acid_.” We have two accounts preserved to us of the original of this invention. The first of which was given by our illustrious countryman, Roger Bacon, called the Wonderful Doctor, who died A. D. 1278; previous to which period, gunpowder must have existed. The other account is by Albertus Magnus, in a work published in 1612.