At three Inches from the hinder Rail of the Coffin, in the middle, between both sides of the Planck, is cut an Hole four Inches square (as at e e) and upon the hither and farther side of this Hole is fastned down on each side a Stud made of Wood (as at f f) and in the middle of these two Studs is made a round Hole about half an Inch over, to receive the two round ends of an Iron Pin; which Iron Pin, though its ends be round, is through the middle of the Shank square, and upon that square is fitted a round Wooden-Rowler or Barrel, with a Shoulder on either side it, to contain so much of the Girt as shall be rowled upon it; And to one end of the Rowler is fastned an Iron Circle or Wheel, having on its edge Teeth cut to stop against a Clicker, when the Rowler with an Iron Pin is turned about to strain the Girt.
¶. 10. Of the Tympan and Inner-Tympan, marked b in Plate 7.
The Tympan is a square Frame, three sides whereof are Wood, and the fourth Iron. Its width is one Foot eight Inches, its length two Foot two Inches; the breadth of the wooden Sides an Inch and an half, and the depth one Inch.
On its short Wooden-side, viz. its Hind-end, at the two Corners is Rivetted an Iron Match-Joynt, to be pinned on to another Half-joynt fastned on the Hind-Rail of the Coffin.
The other end, viz. the Fore-end of the Tympan is made of Iron, with a square Socket at either end for the Wooden ends of the Tympan to fit and fasten into. This Iron is somewhat thinner and narrower than an ordinary Window-Casement.
Upon the outer edge of this Iron, about an Inch and an half off the ends of it, is made two Iron Half-joynts to contain a Pin of about a quarter of an Inch over, which Pin entring this half-joynt, and a match Half-joynt made upon the Frisket, serves for the Frisket to move truly upon.
In the middle of each long Rail of the Tympan, is made through the top and bottom an Hole half an Inch square, for the square Shanks of the Point-Screws to fit into.
The like Holes are also made in the Tympan, at one third part of its length from the Fore-end or Frisket-joynt, to place the Point Screws in; when a Twelves, Eighteens, &c. is wrought.
Into the Inner-side of this Tympan is fitted the Inner-Tympan, whose three sides are also made of Wood, and its fourth side of Iron, as the Tympan, but without joynts; it is made so much shorter than the Outer-Tympan, that the outer edge of the Iron of the Inner-Tympan may lye within the inner edge of the Iron on the Outer-Tympan; and it is made so much narrower than the inside of the Tympan, that a convenient room may be allowed to paste a Vellom between the inside of the Tympan, and the outside of the Inner-Tympan.
About the middle, through the hither-side of the Inner-Tympan, is let in and fastned an Iron Pin about a quarter of an Inch over, and stands out three quarters of an Inch upon the hither outside of the Inner-Tympan, which three quarters of an Inch Pin fits into a round hole made in the inner-side of the Tympan, to gage and fit the Inner-Tympan right into the Tympan; for then by the help of an Iron turning Clasp on the further side the Tympan, the Inner-Tympan is kept firmly down and in its position.