Secondly, That an Apple or a Crust of Bread, &c. stuck upon the end of a Stick instead of an Oynion will also make the Scum of the Oyl rise: For it is only the Air contained in the Pores of the Apple, Crust or Oynion, &c. pressed or forced out by the violent heat of the Oyl, that raises the many Bubbles on the top of the Oyl: And the connection of those Bubbles are vulgarly called Scum.
Thirdly, The English Inck-makers that often make Inck, and that in great quantities, because one Man may serve all England, instead of setting a Caldron on a Trevet, build a Furnace under a great Caldron, and Trim it about so with Brick, that it Boyls far sooner and more securely than on a Trevet; because if the Oyl should chance to Boyl over, yet can it not run into the Fire, being Fenced round about with Brick as aforesaid, and the Stoking-hole lying far under the Caldron.
Fourthly, When for want of a Caldron the Master-Printer makes Varnish in a Kettle, He provides a great piece of thick Canvass, big enough when three or four double to cover the Kettle, and also to hang half round the sides of the Kettle: This Canvass (to make it more soluble) is wet in Water, and the Water well wrung out again, so that the Canvass remains only moist: Its use is to throw flat over the Mouth of the Kettle when the Oyl is Burning, to keep the smoak in, that it may stifle the Flame when they see cause to put it out. But the Water as was said before, must be very well wrung out of the Canvass, for should but a drop or two fall from the sides of it into the Oyl when it is Burning, it will so enrage the Oyl, and raise the Scum, that it might endanger the working over
the top of the
Kettle
.
Having shewn you the Master-Printers Office, I account it suitable to proper Method, to let you know how the Letter-Founder Cuts the Punches, how the Molds are made, the Matrices Sunck, and the Letter Cast and Drest, for all these Operations precede the Compositers Trade, as the Compositers does the Press-mans; wherefore the next Exercises shall be (God willing) upon Cutting of the Steel-Punches.
MECHANICK EXERCISES:
Or, the Doctrine of
Handy-works.
Applied to the Art of
Letter-Cutting.