Fig. 1436.—After the preceding experiment the same bar was reheated and reversed in the water, the eleventh cooling resulting in the above form, the bar bending in the opposite direction from that previously shown.

“Experiment No. 10 was made in order to show the effect of reversing this cooling process. After five coolings, a bar of iron, 28 inches long, 31⁄2 inches deep, and 1⁄2 inch thick, was curved so that the versed sine of its air-cooled edge was 11⁄2 inches. The coolings were then reversed, what was the air-cooled edge being then immersed in water. After five more coolings the bar was restored to within 1⁄8 inch of being straight, and the eleventh cooling threw the concavity on the other side of the bar.

“Experiment No. 10.—Wrought-iron flat bar, 28 inches long by 31⁄2 inches by 1⁄2 inch, heated to dull red, then quenched half its depth in water, up to five heats, then the opposite edge dipped.

Versed sine of
concave, i.e. air-
cooled edge.		 Reversed Cooling.
Versed sine of
concave, i.e. now
water-cooled
edge.
Inches. Inches.
1st cooling 5⁄166th cooling13⁄16
2nd „ 9⁄167th „ 7⁄8
3rd „ 13⁄168th „ 3⁄4 scant.
4th „13⁄89th „ 3⁄8 full.
5th „11⁄210th „ 1⁄8
11th „Brought concavity
1⁄8 in. on other side.

“When the author had proceeded thus far, these curious results were shown to several leading scientific men, who expressed interest in the subject, which encouraged the author to extend his experiments under varied conditions with a view of ascertaining the cause for these anomalous effects. These experiments (Nos. 11 to 17) are fully recorded, and the results shown on the diagrams; the actual rings are also on the table before you.

[Large
image
(49 kB).]

Fig. 1437.

“Experiment No. 11.—Wrought-iron hoop, turned and bored, 37.1 inches, outside circumference, by 2.95 inches deep by .44 inch thick, the grain of the iron running the short way of the bar from which the hoop was made, heated to redness, then cooled half its depth in water (see [Fig. 1437] at a for final form of hoop after ten heatings and coolings).