The following "Classification of Vessels" and "Assignments to man afloat" are hereby established for the Navy in accordance with an act of Congress, approved March 3:
CLASSIFICATION OF VESSELS.
Torpedo Boat Destroyers: Torpedo boats, tugs, sailing ships and receiving ships shall not be rated. Other vessels shall be rated by tons of displacement as follows:
First Rates : Men of War when of eight thousand tons and above.
Second Rates: Men of War of four thousand tons and under eight thousand tons, and Converted and Auxiliary vessels of six thousand tons and above, except Colliers, Refrigerating ships, Distilling ships, Tank-steamers, Reporting ships, Hospital ships and other vessels constructed or equipped for special purposes.
Third Rates : Men of War from one thousand to four thousand tons and Converted and Auxiliary Vessels from one thousand to six thousand tons and Colliers, Refrigerating ships, Supply ships, Distilling ships, Tank-steamers, Report ships, Hospital ships and other vessels constructed or equipped for special purposes of four thousand tons and above.
Fourth Rates : All other vessels.
William McKinley, Executive Order Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/205637