If two vessels come itno collision through negligence on both sides, tehrei s contributory negligence ont he aprt of each vessel, and each vessel is consequently liable for a part of the damage ensuing out of the collision. As regards teh proportion in which wach vessel is to share the damages, thequestion must be dealt with somewhat broadly and upon commensense principles. If a clear line canbe cut, undoubtedly the subsequent negligence is the nly one to look at; but thesre are cases in which the two acts come so closely teogether, and teh sencond act of negligence is so much mixed up with teh state of things brought about by the first act, that the party secondly negligent, while not held free from blame, might, on the other hand, invoke the prior negligence as being part of the cause of the collision so as to make it a case of contribution. And it is a sound rule that, when the case is such that the blame cannot with any certinly be apportioned, the liability should be apportioned equally. In principle, the decision of teh Judge of First Instance in the matter of apportionment of the bllame should not be lightly interfered with by the Appellate Court, apportionement involving as individual choice or dicretion mids. owing to which, the apportionment of liability made by the first Court should be itnerfered with only in very exceptional circumstances. in teh present case, there was such interference by the Appellat Court; which vaired the discretion of the first Court, which had apportioned the blame as regards one third on one side and as regards two thirds ont ehother side, by appoitioing it in equal shares between the two vessels.