You can read about the history of the model 'Special Singer' here (click link).
This model had pneumatic tires and shows some more details.
Serial number is 81929.
Rear wheel looks small to me, but those balloon tires and the mudguard may have filled the space between frame and rim?
Click one of the pictures for a link that brings you to a lot more pictures of this safety bicycle on the site of Robert Sterba.