How stoppage in transitu is effected

(l) The unpaid seller may exercise his right of stoppage in transitu either by taking actual possession of the goods or by giving notice of his claim to the carrier or other bailee or custodian in whose possession the goods are. (2) Such notice may be given either to the person in actual possession of the goods or to his principal, and in the latter case the notice, to be effectual, must be given at such time and under such circumstances that the principal, by the exercise of reasonable diligence, may communicate it to his servant or agent in time to prevent a delivery to the buyer. (3) When notice of stoppage in transitu is given by the seller to the carrier, or other bailee or custodian in possession of the goods, he must re-deliver the goods to, or according to the directions of, the seller, and the expenses of such re- delivery must be borne by the seller. Effect of sub- sale or pledge by