Possible Clues:

• A volume to absorb half-bookish type
• Scholarly (person)
• Fellow of no practical importance
• Brainy fellow
• Irrelevant theorist
• Plug in fantastic device to transmit sound of educational kind
• A learned rotter might have the mice in bits
• Unimportant fellow
• Change I made in a carbon copy for reader perhaps
• Hypothetical man of letters