The issue did not concern the law of mistake but the application of the forfeiture provisions contained in the tender documents. The deposit was recoverable by the contractor under certain conditions, none of which was met, and also was subject to forfeiture under another term of the contract, the conditions of which had been met. The omission by the owner to insert the number of weeks specified by the tender in the appropriate blank in the contract had no bearing on the rights of the parties to the appeal and did not stand in the way of the owner’s asserting its right to retain the deposit.