The significance of the Campbell v. City of Haverhill case is that it established the principle that a party who excepts to a ruling of the court but then proceeds with the trial waives their right to appeal that ruling. The case involved an action by Ruel Philbrook and others, including Christopher C. Campbell, against the city of Haverhill to recover for the city's infringement of certain patent rights belonging to the plaintiffs. The court ruled that the state statute in question had been displaced by section 55 of the patent act of 1870, which provided that all actions must be brought during the term for which the letters patent were granted or extended, or within six years after the expiration thereof. The case was significant because it established an important precedent regarding the waiver of exceptions in patent infringement cases.