The Three Musketeers by Alexandre Dumas Chapter 49 Page 17

However flattering this compliment, the officer made no reply; but drawing from his belt a little silver whistle, such as boatswains use in ships of war, he whistled three times, with three different modulations. Immediately several men appeared, who unharnessed the smoking horses, and put the carriage into a coach house.

Then the officer, with the same calm politeness, invited his prisoner to enter the house. She, with a still-smiling countenance, took his arm, and passed with him under a low arched door, which by a vaulted passage, lighted only at the farther end, led to a stone staircase around an angle of stone. They then came to a massive door, which after the introduction into the lock of a key which the young man carried with him, turned heavily upon its hinges, and disclosed the chamber destined for Milady.