The New Student's Reference Work/Dry Tortugas

Dry Tortugas, a group of ten islets forming part of Florida, at the end of the Florida keys. They are of coral formation and are low and barren, except where covered with low bushes. On one of them are Fort Jefferson and a lighthouse. During the Civil War the fort was used to imprison Confederate prisoners, and several men who were convicted of having been concerned in the conspiracy to assassinate Lincoln were confined there.