59The unpaid seller may exercise the right of stoppage in transit either by taking actual possession of the goods, or by giving notice of the seller’s claim to the carrier or other bailee or custodian in whose possession the goods are, which notice may be given either to the person in actual possession of the goods or to that person’s principal, but in the latter case the notice to be effectual shall be given at such time and under such circumstances that the principal, by the exercise of reasonable diligence, may communicate it to a servant or agent in time to prevent a delivery to the buyer.