[kaolinite]

That really would make a fantastic gift for your friend, although you're right - they are rather expensive :-)

> That claim about wristwatches not being popular...

Agreed, it certainly seems obvious. I suspect at the time there may have been some advances that allowed smaller wrist watches, and that's what allowed them to take off - however that's just a guess. Women's watches at the time were quite large and elaborate, covered in jewels and such.

There's quite a good NYTimes article you might like, though it doesn't go into much detail about Santos-Dumont: http://mobile.nytimes.com/2013/10/23/fashion/wrist-watches-f...

There's also a bit more information on the Cartier Santos watch, including its modern variants, here: http://monochrome-watches.com/history-of-the-pilot-watch-par...