August 14, 1919
The U.S. Post Office Department, pushing the bounds of airmail and its applications further than ever before, conducted its first official delivery of mail via plane to a ship after it had already left port to sail across the ocean. This pioneering experiment took place when pilot Cyrus J. Zimmerman flew a seaplane to deliver mail to the White Star Line ocean liner RMS Adriatic after the vessel had departed Hoboken, New Jersey, for a transatlantic voyage to Europe.
Despite adverse weather conditions that day, Zimmerman was able to successfully drop off the mail on board the ship. “The perfect performance of this experiment according to program was greeted by cheers and clapping on board the Adriatic,” reported Aircraft Journal.
New York City postmaster general (and former U.S. congressman) Thomas G. Patten worked with David Lindsey of the International Mercantile Marine, which operated the White Star Line, to help bring about this mail delivery effort out at sea. The key logistical part of the effort involved Patten overseeing arrangements with Inglis M. Uppercu, president of the Aeromarine Plane and Motor Company, to secure a “flying boat” — a fixed-wing seaplane with a hull — for the delivery.
Zimmerman, accompanied by mechanic Richard Griesinger, took to the skies in that seaplane from the Columbia Yacht Club at 86th Street in New York City. After circling above the Adriatic and in the face of strong winds a couple of times, Zimmerman finally managed to maneuver the plane to a lower altitude at a maximum speed of 45 miles (72.4 kilometers) per hour and not more than 50 feet (80.5 kilometers) over the ship’s mast tops for the mail drop.
Aircraft Journal recounted, “As the plane passed over the Adriatic, a specially devised weighted cable with shock absorbers was released, catching and wrapping itself around a cable which ran from the masthead to the deck.” This magazine then noted, “The mail pouch was pulled out when the cable contracted, dropping into the water. The pouch was then quickly hauled on board.” Joseph B. Ranson, captain of the Adriatic, subsequently sent a wireless message to the White Star Line office in New York to confirm the success of Zimmerman’s shore-to-ship delivery on behalf of the U.S. Post Office Department. (The above illustration appeared in the October 1919 issue of Electrical Experimenter magazine.)
Image Credit: Public Domain
Additional information on Cyrus J. Zimmerman’s pioneering 1919 shore-to-ship mail delivery flight is available at https://chroniclingamerica.loc.gov/lccn/sn83030214/1919-08-15/ed-1/seq-16/
Transportation History 
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