Sentence:  I am living fast to see the time when a book that misses its tide shall be neglected, as the moon by day, or like mackerel a week after the season. No man has more nicely observed our climate than the bookseller who bought the copy of this work; he knows to a <WSD>tittle</WSD> what subjects will best go off in a dry year, and which it is proper to expose foremost when the weather-glass is fallen to much rain. 
Meaning of the word marked with <WSD> tags:  A small, insignificant amount (of something); a modicum or speck.