Baltimore Sun, May 29, 1922, page 20:

ENTIRE  CITY  TO  HEAR  ADDRESS  BY  HARDING
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Radios  In  Every  Public  Square  To  Spread  President's  Flag  Day  Speech.
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WILL  USE  RELAY  SYSTEM
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Message  First  To  Go  To  Big  Anacostia  Plant  And  Then  To  Be  Broadcasted.

    It is planned by Frederick R. Huber, a member of Mayor Broening's committee arranging for the Francis Scott Key memorial unveiling June 14, to have President Harding's voice carried by radio to every public square in Baltimore. In this way thousands who will be unable to gain admittance to Fort McHenry will be able to go to the square nearest their homes and hear the address as it is being made.
    Mr. Huber, representing Baltimore, and Lieut. Col. C. O. Sherrill, representing Secretary of War Weeks, are making arrangements with the Government for the use of the broadcasting station at Anacostia, D. C., to carry the President's voice after it has been relayed there by long-distance telephone. The voice then will be sent back by radio to the various receiving stations in Baltimore.

Will  Use  Relay  Tomorrow.

    Colonel Sherrill is making arrangements for the use of the Anacostia station for the Lincoln memorial services at Washington tomorrow. Immediately after the Washington celebration Colonel Sherrill will set to work on a plan to secure the plant far use when President Harding makes his address here.
    The original plan was, according to Dr. Huber, to have a broadcasting station built in Baltimore, but the cost would be about $30,000, which is prohibitive for the city. Mr. Huber believes that with the cooperation of the Chesapeake and Potomac Telephone Company, which is furnishing the amplifier, it will be just as satisfactory to have the voice relayed.

First  Tried  Last  November.

    Such messages have been relayed before, but on a different plan and by means of wires, as the talk across the continent last November. Since that time the radio has sprung into overnight prominence and Colonel Sherrill says there is widespread interest over the working-out of the relay plan.
    The amplifier, which will be erected over the President's speaking stand, will carry his voice half a mile, so that people outside the fort, who are unable to see him, will be able to hear his voice, as will passengers on boats passing in the Patapsco river.