At the trial, after the testimony had been concluded, the foreman of the jury (a lawyer by profession) inquired of the court whether the jury might not find a special verdict, leaving it to the court to say whether on the facts as found the defendants were guilty.
I have problem understanding the bold text. I already assume it means that the foreman of the jury announced to the court that they might be unable to find a special verdict ... However, I doubt if this is true. Use of inquire+of and followed by negative whether they might not find seems weird to me. So, generally, I thought that "whether" here might convey some type of possibility.