Sentence:  A half crown <WSD>tip</WSD> put the deputy's knowledge at my disposal, and I learned that Mr. Bloxam [...] had left for his work at five o'clock that morning. 
Meaning of the word marked with <WSD> tags:  A gratuity; a small amount of money left for a bartender, waiter, taxi driver or other servant as a token of appreciation. (From mid-18th c.)