Meanings of spanish ducats in English

He had obviously, they thought, been purchased by Spanish ducats to do what he had hitherto been so steadily refusing.

There they found that she had on board pure gold amounting to thirty-seven thousand Spanish ducats, stores of good wine, and other treasure.

While constantly looking out for fresh water, they discovered a Spaniard lying asleep, probably drunk, with a bag containing four thousand Spanish ducats.