173 Rue Saint-Jacques

The Age Of Reason, p.244
He went out, thinking: 'Where can she be?' His head was empty and his hands were trembling. A cruising taxi was passing down Rue Froidevaux. Mathieu stopped it. 'Student's Hostel, 173 Rue Saint-Jacques. Quick.'
'Right.' said the chauffeur.
'Where could she be? At the best she had already left for Laon; at the worst ... And I'm four hours behind,' he thought. He leaned forward and pressed his right foot hard on the mat, as though he were accelerating.
The taxi stopped. Mathieu got out and rang the bell at the hostel door.
'Is Mlle Ivich Serguine in?'
The lady eyed him dubiously. 'I'll go and see,' she said.
She returned almost at once. 'Mlle Serguine hasn't been in since this morning. Is there any message?'
'No.'