To fill that need, library patrons had to use the bathroom at the Roxbury Union Congregational Church. It was a friendly arrangement as "Library patrons always obeyed the Please jiggle my handle after you flush sign." [Sorry, I'm not making and handle jiggling church or priest jokes with that one, but feel free to indulge yourself.]
Both children and adults had to go before they left home or rush next door when necessary. The most famous incident of someone needing the facilities occurred in 1951 when Robert Frost visited the library for a poetry reading. As he recited "Stopping by Woods on a Snowy Evening," he was taken with severe stomach distress which he incorporated into his famous verse:
The woods are lovely and darkly swoop.
Oh, forgive my stomach's loop-de-loop.
But I really need some place to poop.
How many miles before I poop?
The audience in attendance didn't realize that Mr. Frost was asking for the nearest lavatory, but thought he was merely improvising. As they politely applauded, Frost ran out the front door and made use of the darkest evening and the snowy woods and frozen lake nearby to relieve himself.
"Life imitates Art," the local paper reported.