I understood at once from that expressive "Ah!" that Leroy knew and had recognised the vessel, and that my pretence of ignorance would no longer serve any good purpose.  I therefore determined to abandon it and to make a virtue of necessity by frankly admitting my knowledge.  For if Leroy recognised the schooner, as I was certain he had, he would be fully aware of the fact that I, as an officer of the Slave Squadron, must necessarily know her too.  After regarding her attentively through the lenses, therefore, for more than a minute, I passed the glass back to the chief mate with the quiet remark: