MR. LEWIS ABBOTT'S letter in NATURE of October 22 is almost entirely irrelevant to the subject of my communication to NATURE of September 24. In this note I dealt solely with one form of flint ...

You want the stone to exhibit what’s called conchoidal fracture. If you’ve ever seen glass break, you’ve witnessed conchoidal fracture. This smooth break, ...

Researchers have observed wild-bearded capuchin monkeys in Brazil deliberately break stones, unintentionally creating flakes that share many of the characteristics of those produced by early Stone ...