ballon d'essai

This little ballon d'essai met the fate of many such, for the manuscript was returned within a fortnight.

That was a ballon d'essai, as they call it, and they think it was a very happy one.

The first born is a ballon d'essai.

The Germans would simply use the small offer, not as a ballon d'essai, but as a means of inaugurating direct negotiations.

She was not a ballon d’essai; she was literally the whole show; and if she duplicated the sensational success of poor little Miss Claridge, we had nothing to fear.