252 DRAUGHT OF MILL-STONES. [Chap. 13.

2; shift to 2, and continue to 1, and the curve of thefurrow is formed, as 1—6 in the figure.

6. To this curve form a pattern, by which to lay out allthe remainder.

The furrows with this curve will cross each other withthe following angles, shown fig. 1,at circle 1, which is the eye

of the stone, at 75 degrees angle,

— 2 45

— 3 35

— 4 81

—5 - - 27

— 6 23

These angles, as shown by the lines G r, H r, G s, H s,&c. &c., will I think, do well in practice, will grindsmooth, and make but little coarse meal, &c.

Supposing the greatest draught circle to be 6 inchesradius, then, by theory, the angles would have beenat circle 1 - - - 138 degrees angle.

— 2 69

— 3 46

— 4 35,5

— 5 - - - 27,5

— 6 23

If the draught circle had been 5 inches radius, and thefurrows straight, the angles would then have been at

circle. degree?

1 about 180

And 6 inches from centre, as shownby lines G 1, H 1,

2

3

4

110

60

38

29

23

18

Here, the angles near the centre are much too greatto grind, and they will push the grain before them; toremedy this disadvantage, take the aforesaid rule, whichforms the furrows, as shown at 6—7, fig. 1, which is 4of 18 qrs. H 8 represents a furrow of the runner, show-

v