What do you infer from Sam's letter to Charley?

Explanation

Sam had gone to the third level. Then had travelled into the old time zone. He appears to like that old time. He was very comfortable and happy there. He had requested Charley and his wife to come there. But Sam has been living with Charley. Discovering the letter of Sam dated 1894 is slightly out of place. Thus it was an imagination of Charley.