The night was extremely dark.

It was almost impossible to see the shore from the boat; they would therefore be less likely to see the boat from the shore.
A black point floated on the sea.

That was the sloop.

While the boat was advancing with all the speed its four rowers could give it, Felton untied the cord and then the handkerchief which bound Milady's hands together.

When her hands were loosed he took some sea water and sprinkled it over her face.
Milady breathed a sigh, and opened her eyes.
"Where am I ?" said she.
"Saved!" replied the young officer.
"Oh, saved, saved!" cried she.