A Bridge portable in[1] a Cart with six horses, which in a few hours time may be placed over a River half a mile broad, whereon with much expedition may[2] be transported Horse, Foot and Cannon. Footnotes [1] upon a. MS. and P. [2] there may be. [_A portable Bridge._] The great painter, Leonardo da Vinci, born in 1452, and who died at 67 years of age in 1520, was a man of singularly inventive talent. Among his other projects, he declares:--“I have the means of constructing light bridges, easy of carriage, and equally adapted to pursue or escape an enemy, secure from fire; and as easy to remove as to replace; and also the means of destroying those of the enemy.” See an interesting Memoir of him by J. W. Brown. 12mo. 1828. Bourne’s 94th Device promises, “How you may make a bridge upon a sudden, that a whole army of men and their carriages may pass over any river or haven, if that it be of not too great breadth.”--See his Inventions or Devices, 1578. Sir Hugh Plat, in his “Jewel House of Art and Nature,” 1653, shows, in article No. 22, “How to erect or build over any brook, or small river, a cheap and wooden bridge of 40 or 50 feet in length, without fastening any timber work within the water.” 29. A portable Fortification able to contain five hundred fighting men, and yet[3] in six hours time may[4] be set up, and made Cannon-proof, upon the side of a River or Pass, with Cannon mounted upon it, and as complete as a regular Fortification, with Half-moons and Counterscarps. Footnotes [3] yet--omitted. [4] able to be--for, may be. [_A moveable Fortification._] Vegetius, in “De re militari,” 1535, offers many similar schemes but less ambitious than the present one; which is, after all, little if any more than an extension and improvement on what had previously been more or less practised. In his “Naturæ simia seu technica,” dated 1618, Robert Fludd, at page 421, gives a folio engraving of a triangular fort, with six pieces of cannon and three gunners. It appears to be on wheels, and is pushed along by a beam running on three wheels, having four horses yoked to it; literally the cart before the horse. 30. A way in one nights time to raise a Bulwork twenty or thirty foot high, Cannon-proof, and Cannon mounted upon it, with men to overlook, command and batter a Towne; for though it contain but four Pieces, they shall be able to discharge two hundred Bullets each hour. [_A Rising Bulwork._] Grose, in his “Military Antiquities,” Vol. I. Page 355, notices a moveable tower, the use of which was revived by the Royalists in their attack on Gloucester, during the Civil War.