m, b, c, n

This instrument is for making a spring to give motion to a clock. And it is made in this way: a piece of steel is made in the form shown, n b. And it is placed in the instrument in the way you see. And with the screw m it is clamped against the steel c, so that it stays firm. And then this steel rod is drawn by force of a screw, at a bench, in the way that drawn iron (wire) is drawn. And then it is annealed and put back into the draw-plate c, somewhat narrower than before, and drawn again. And so, always annealing and re-drawing, so much is done that it reaches the thickness of a thick sheet of paper. Then coil it, and put it in its case in the way you know. Then temper it and let down the temper to the blue color in molten lead, or if you wish in a furnace such as is used where glass is worked, so that it draws the temper evenly throughout. And then use it as suits you. And because steel is here hard and there soft, each piece of the rod must be upset at the head and welded crosswise, squared as you have it for use like a die. And weld them well together, then draw them out, and pull it as said through the draw-plate. Then coil it with an iron wire in the middle, between turn and turn, so that its spaces are equal. Then temper and let down in molten lead, so that it goes evenly throughout.

All the forces you make screws exert, make that they rather pull than push. Because in pushing they twist or bend, and in pulling they straighten. And if you were nonetheless constrained to push with such screws, make them short and thick. And I remind you that when you have to put many screws to work, make that all in equal time give an equal turn; otherwise the one that pulls more loads itself more and breaks its threads. And if it does resist the weight, it twists the nuts upon the other screws, and the motion becomes much more difficult.