With regard to the act of God, it was a general principle, not peculiar to carriers nor to bailees, that a duty was [202] discharged if an act of God made it impossible of performance. Lord Coke mentions the case of jettison from a Gravesend barge, /1/ and another of a party bound to keep and maintain sea-walls from overflowing, as subject to the same limitation, /2/ and a similar statement as to contracts in general will be found in the Year Books. /3/ It is another form of the principle which has been laboriously reargued in our own day, that parties are excused from the performance of a contract which has become impossible before breach from the perishing of the thing, or from change of circumstances the continued existence of which was the foundation of the contract, provided there was no warranty and no fault on the part of the contractor. Whether the act of God has now acquired a special meaning with regard to common carriers may be left for others to consider. It appears, from the foregoing evidence, that we cannot determine what classes of bailees are subject to the strict responsibility imposed on common carriers by referring to the Praetor's Edict and then consulting the lexicons under Nautoe, Caupones, or Stabularii. The question of precedent is simply to what extent the old common law of bailment still survives. We can only answer it by enumerating the decisions in which the old law is applied; and we shall find it hard to bring them together under a general principle. The rule in Southcote's Case has been done away with for bailees in general: that is clear. But it is equally clear that it has not maintained itself, even within the limits of the public policy invented by Chief Justice [203] Holt. It is not true to-day that all bailees for reward exercising a public calling are insurers. No such doctrine is applied to grain-elevators or deposit-vaults. /1/