He laughed at that. The unease Jane thought she had seen vanished, and his countenance was open once more. ‘Rather, a distrust of servants. In London, I had no fear of those with whom they might share my letters.’

‘And here?’

Vincent ran his hand through his hair and stopped with it tangled at the back of his head. ‘What do you see on my desk?’

Here at last was the chief source of her interest. ‘One of the glass balls we made yesterday.’

Nodding, he picked it up. ‘Specifically, this is the Sphère Obscurcie.’

And yet he and it had been perfectly in view when she entered the room. ‘Are you certain it was not exchanged for another?’

‘The inclusions in the glass seem to be identical to those we created yesterday.’ He held it out to her. ‘I do not wish you to exert yourself, but I trust your eye in such things better than I do my own.’

Pleased that he thought so highly of her discernment, Jane took the ball. It had more weight to it than she had supposed, and seemed to retain some warmth from the fire. To both her naked eye and her expanded view, the patterns in the glass seemed to match exactly those they had created.

‘Do you think it needs the heat?’

‘I had the same thought, but taking it nearer the furnace produced no effect.’

‘Is that why it is warm?’

He nodded. Jane turned the glass over in her hand, the faint imperfections they had introduced catching the light. ‘Did you try glamour?’

‘I did, but neither Mathieu nor I saw any result.’ He shrugged. ‘I cannot account for it.’

She handed the ball back to him. ‘May I see?’

Walking a few steps away, Vincent folded a piece of glamour into the glass. It went in, swirled, and exited, but Vincent remained stubbornly in view. He might have faded a little, but it was nothing to what they had seen before.

She thought, though she was not certain, that the glamour was significantly diffused when it exited the sphere. Jane reached out to feel the folds on both sides of the glass, to ascertain by tactile sense the difference between the glamours.

A wave of nausea struck her within moments of touching the folds. She barely had time to withdraw her hand and stagger to the ash bin before she lost what little she had been able to eat that morning. Vincent tossed the glass ball on the wingback chair and hurried to her side, holding her shoulders till the worst violence of her illness had abated.

Jane’s shame at this weakness was acute. ‘Forgive me.’

‘Forgive you? No, the fault is mine entire. I should know better than you the results of over-exertion.’ Vincent helped her to her feet with gentle solicitude. ‘Let me tend you as you tended me.’