Mrs.Rhinehart hoped that the following evening would be convenient for Miss Ludington.

She had assumed the responsibility of making the engagement positive, as she might have failed in securing a seance altogether had she waited to communicate with Miss Ludington.
Hoping that "the conditions would be favourable," she remained, &c.

&c.
When Miss Ludington had read this letter to Paul, she intimated, though rather faintly, that it was still not too late to withdraw from the enterprise; they could send Mrs.Legrand her fee, say that it was not convenient for them to come on the evening fixed, and so let the matter drop.

Paul stared at her in astonishment, and said that, if she did not feel like going, he would go alone, as he had at first proposed.

Upon this Miss Ludington once more declared that they would go together, and said nothing further about sacrificing the appointment.
The fact is she did not really wish to sacrifice it.