from The Century Dictionary and Cyclopedia
- n. An alley at the side or somewhat out of the way.
Sorry, no etymologies found.
In Moscow they abound in every street, lane, and by-alley.
We followed the advice of a railway attendant in going first to the May Pole, which proved to be a commercial inn, with the air of a drinking-shop, in a by-alley; and, furthermore, they could not take us in.
He gave the pocket, as soon as he had plucked it off, to his comrade, but having felt it rather weighty, would trust him no farther than the first by-alley before they stopped to examine its contents.