The Middle Ages are usually considered to have closed between 1490 and 1500, only one century previous to the birth of that Marquis of Worcester to whom posterity is indebted for his ever memorable publication, the “Century of Inventions,” of which a reprint is now before the reader. It records the earliest full, though brief, sketch of a practically working Steam-Engine; an invention which, whether in relation to the age in which it was produced, or the difficulties under which it was wrought out, cannot be considered otherwise than as a marvellous effort of ingenuity. The literature and science of that era, as compared with the progressive stages of improvement distinguishing the two succeeding centuries, were barren and meagre indeed. Hallam justly observes: “Learning, which is held pusillanimous by the soldier, unprofitable by the merchant, and pedantic by the courtier, stands in need of some countenance from the ruling powers before whom all three bow down.” But even at that early period Leonardo da Vinci, born 1452, had anticipated Lord Bacon in the universally accepted principle, that experiment and observation must ever be the only sure guides to the forming of just theories in the investigation of nature. The “Century of Inventions” derives its name rather from the circumstance of the work containing one hundred articles, than the same number of inventions. Its noble author may have had in mind the _Centuria di Secreti Politici, Cimichi, e Naturali_, by Francesco Scarioni of Parma, duodecimo, printed at Venice in 1626, when he fixed on the quaint title of his own remarkable production. Among the Harleian Manuscripts in the British Museum Library is a manuscript copy of the “Century,” the title of which omits the words “at the instance of a powerful friend,” also the motto, date, dedications, and author’s name. It also differs in other respects from the printed edition, by introducing “A stamping Engine” as the 88th article, in place of which its author has printed his account of “A Brazen Head;” the concluding article likewise varies, especially in closing with a short notice of “three sorts” of other inventions “set down in cypher,” but which do not appear. The top of the title page has written on it “From August ye 29th to Sept. ye 21st 1659,” probably by the copyist, to notify the time occupied in writing.