Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 152.
Jokkmokk [2], 21/07/1732, ¶815:
The average thickness of the whole ski is 1/4 to 1/3 of an inch. The ski is also slightly concave underneath and has a shallow furrow along its length.