Between the two Side-Rails are framed into the two End-Rails the two Wooden-Ribs two Inches and an half broad, and an Inch and an half thick; they are placed each at an equal distance from each Side-Rail, and also at the same distance between themselves. Upon these two Ribs are fast Nailed down the Iron-Ribs, of which more shall be said when I come to speak of the Iron-work.
¶. 9. Of the Carriage, Coffin and its Planck, marked a in Plate 7.
The Planck of the Carriage is an Elm-Planck an Inch and an half thick, four Foot long, and one Foot eight Inches and three quarters broad; upon this Planck at its fore-end is firmly Nailed down a square Frame two Foot four Inches long, one Foot ten Inches broad, and the thickness of its Sides two Inches and an half square; This Frame is called the Coffin, and in it the Stone is Bedded.
Upon each of the four Corners of this Coffin is let in and fastned down a square Iron Plate as at a a a a, with Return Sides about six Inches long each side, half a quarter of an Inch thick, and two Inches and a quarter broad; upon the upper outer-sides of each of these Plates is fastned down to them with two or three Rivets through each side, another strong Iron half an Inch deep, and whose outer Angles only are square, but the Inner-Angles are obtuse, as being sloped away from the Inner-Angle towards the farther end of each inner-side, so as the Quoins may do the Office of a Wedge between each inner-side and the Chase.
Plate 7.
The Plates of these Corners (as I said) are let in on the outer Angles of the upper-side of the Frame of the Coffin, so as the upper-sides of the Plates lye even with it, and are Nailed down, or indeed rather Rivetted down through the bottom and top-sides of the Frame of the Coffin, because then the upper-sides of the Holes in the Iron Plates being square Bored (that is, made wider on the upper-side of the Plate, as I shall shew when I come to the making of Mathematical Instruments) the ends of the Shanks of the Iron Pins may be so battered into the Square-boring, that the whole Superficies of the Plate when thus Rivetted shall be smooth, which else with the exturberancies of Nail-heads would hinder the free sliding of the Quoins.
At the hinder end of the Frame of the Coffin are fastned either with strong Nails, Rivets, or rather Screws, two Iron Half-Joynts, as at b b, which having an Iron Pin of almost half an Inch over put through them, and two Match-half-Joynts fastned on the Frame of the Tympan, these two Match-half-Joynts moving upon the Iron Pin aforesaid, as on an Axis, keeps the Tinpan so truly gaged, that it always falls down upon the Form in the place, and so keeps Register good, as shall further be shewed in proper place.
Behind the Coffin is Nailed on to its outside, a Quarter, as at c c this Quarter is about three Inches longer than the breadth of the Coffin, it hath all its sides two Inches over, and three of them square; but its upper-side is hollowed round to a Groove or Gutter an Inch and an half over. This Gutter is so Nailed on, that its hither end standing about an Inch higher than its further end, the Water that descends from the Tympan falling into it is carried away on the farther side the Coffin by the declivity of the farther end of the Gutter, and so keeps the Planck of the Carriage neat and cleanly, and preserves it from rotting.
Parallel to the outer-sides of the hind part of the Planck of the Carriage, at three Inches distance from either side, is Nailed down on the upper-side of the Planck two Female-Duftail Grooves, into which is fitted (so as they may slide) two Male-Duftails made on the two Feet of the Gallows (as at d d) that the Tinpan rests upon; and by the sliding forward or backward of these Duftail Feet, the heighth of the Tinpan is raised or depressed according to the Reason or Fancy of the Press-man.