Poole’s thoughts are revealed through dialogue and Poole’s feelings are revealed through the way he speaks.
Poole expresses that he thinks there was foul play, revealing through the dialogue what his thoughts are. Because his voice is hoarse, the reader knows his feelings; he is shaken, emotionally distressed.
The narration directly reveals Mr. Utterson’s thoughts and feelings.
As for the lawyer, the narration goes into his mind and describes his thoughts as they are being processed. The way he observes the buttler, his impressions, how he feels about them, are all expressed by the narrator. For example, in "cried the lawyer, a good deal frightened and rather inclined to be irritated", and in "he observed with great wonder".