"The weather is changing. The wind is quite strong and there are white horses on the sea."
Agatha Christie. And Then There Were None. p.97 (1939)
---
a mighty breath of wind which whipped the lake into fury so that they could hear breakers roar upon the shoals, and the whole lake was covered with tossing white horses,
Cecil Scott Forester. The African Queen, p.155 (1935)
---
First comes white-horse, so called, which is obtained from the tapering part of the fish, and also from the thicker portions of his flukes. It is tough with congealed tendons— a wad of muscle— but still contains some oil. After being severed from the whale, the white-horse is first cut into portable oblongs ere going to the mincer. They look much like blocks of Berkshire marble.