The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.

SECT. I. A Description of the Mortar-Piece, and how to make one of Wood, and Past-Board (for a need,) Brass and Iron ones being wanting.

THe same Metal that makes the best sort of Brass-Ordnance, they make Mortar-Pieces with, and by these Measures; if the Diam. or Bore be 9 Inches, let the Mortar be one Foot and half in length, and let the Chamber in which you Load your Piece with Powder be 3 Inches Diam. and 4 and a half deep; the thickest of the Metal above the Touch-hole 3 Inches, and the upper part thereof 1 Inch ½.

To make the Mortar-Piece of Wood and Past-Board.

Provide a Wooden-Ruler of such bigness as you desire to make the Diameter of the Morter, then grease your Ruler well, that the stuff may slip off that is put about him, which is Past-Boards and Canvas, and very well plyed with hot Glue; and after let it dry a little while on the Rowler, and another while off from the Rowler; and when this kind of Trunk is very dry, put it on the Ruler, and set it in a Lathe, and cut off both ends of the Trunk with a Chizel very even, then turn a Foot thereto with a shoulder to put the Trunk upon, and in the middle thereof make the Chamber for your Powder; if the Piece be 8 Inches in the Mouth, let the thickness of the Past-Board-Trunk be two Inches thick, and 18 Inches long, the Britch or Foot 10, the Shoulder 2 Inches long, and 2 high, that when the Trunk is put on this Shoulder, and joyned with the

Wood, it may be just even with the same; the Bore into which you put your Powder must be two Inches high, and three deep, Plated with Copper, Lattin, (if it be possible) as also all the rest of the Wood that goeth into the Trunk; when you have put the Trunk into the Britch of Wood, nail it round about the Shoulder, by making holes for the Nails, and then driving in the Nails upon that Wood, that you made to receive the Past-boards or Trunk; then cover both Wood and Trunk with good Belch-Cord and Glue again, and let it be well dryed, it will last a long time; and with such you may Shoot Ballouns into the Air for Recreation.