instructed the jury that if they should be of opinion from the evidence that the plaintiff was prevailed upon by the defendant to procure in Boston for the defendant, and as his agent, the plank in question, and as his agent, to cause it to be transported to Alexandria, and that no particular orders were given as to the quality, and that the plank was of a quality merchantable according to the inspection in Boston, and transported to Alexandria, then the defendant was bound to receive it according to the Boston inspection. But if the plaintiff had contracted to sell and deliver the plank to the defendant in Alexandria, the defendant was not bound to receive it unless it was merchantable according to the Alexandria inspection. And that if any particular quality was contracted for or ordered, the defendant was not bound to receive any other quality.