Note by Conduitt on tempering puncheons

Puncheon

It is made of steel which is brought from Germany & c{illeg}ossts {illeg} about 7d a pound, it is bound about with iron {illeg}round & at the bottom to prevent its cracking by the force of the press –

Before the Egraver works upon it it is nealed – that is, it is put wi the place into a charcoal fire where the head is to be downwards into the fire, & resting upon dust of charcoal burnt which keeps the

vidi– When the head is made it is put into a round iron vore Which has in it dust of leather burnt being made of old shoes the head is put downwards & where, that is the finest some of the said dust dust being sifted {sic} finely sifted is put towards that & that & the other dust together round it so high as to prevent any air coming to {illeg} nthe head, for if any air came to it it would scale the head it, sometimes wood soot is used but that does not performe the work smooth so smooth. well as dust of leather — Then it is put into a charcoal fire, where it sl is kept about half an hour if the furnace has not been, heated before if it has less time will do they judge when it comes out is proper to take it out by seeing it whether it is red hot in all its partes — They neal the water that is soften it with a red hot iron bar & then take the puncheon out of the fire & put it as quick as they can into the water for if it stays too long in the air it will scale, & stir it about in it as long as it hisses & then leave it 4 or five minutes afterwards in the water to cool, for if you take it out too soon it <8v> will crack & fly, then clear the puncheon with sand & water & then try by a file & chissole wether it be hard if it turns the chissell it is hard enough — When it happens to be too much hardened they heat 3 iron rings & put them when red hot round the puncheon but when it is too soft they haue no remedy —

Die —

<9v>

Course of a puncheon.