Henderson's "gyroscopic stabilizers being installed through the side of the ship while in dry dock at the Philadelphia Navy Yard on 13 April 917. To accomplish this, the two gyro units were placed on a barge and docked with the ship. Two plates were then removed from the side of the ship, and the gyros were skidded down on to their foundations inside. Each of the gyro units weighed about 30 tons." (quoted from the original 1917-vintage photo caption).
