(b)if one party fails to appoint an arbitrator, either originally or by way of substitution as aforesaid, for fifteen clear days after the sence by the other party of a notice in writing to make the appointment, such other party having appointed his arbitrator before giving the notice, the party who has appointed an arbitrator may appoint that arbitrator to act as sole arbitrator in the reference, and his award shall be binding on both parties as if he had been appointed by consent:
