2. Set-off and recoupment, § 41*—when verdict disallowing claim in recoupment sustained by evidence. In an action to recover on a contract between an individual and a municipality for the disposition of garbage by means of water transportation, where it was admitted that a certain sum was due plaintiff on the contract, but where defendant sought to recoup on the ground of an unseaworthy boat, whose sinking occasioned loss to defendant, a finding for plaintiff held not palpably against the weight of the evidence.3. Navigable waters, § 4*'—what are. The Chicago River is a navigable stream under the control of the Federal government.4. Set-off and recoupment, § 18*—when municipality may not recoup expense of removing obstruction in navigable stream. In an action to recover on a contract between an individual and a municipality for the disposition of garbage by means of water transportation, where it is admitted that a certain sum is due plaintiff on the contract, defendant cannot recoup on the ground that the sinking of an unseaworthy boat caused an obstruction whose removal caused defendant expense, where it appears that the sinking took place in a navigable river, since defendant could not have been compelled to remove the obstruction, and cannot enforce a claim against plaintiff for expense incurred in voluntarily performing a duty not cast upon it by law.