Question

3. What proof does Charley find to show that the Third Level really exists?​

Answer 1

Explanation:

Now, Charlie's Grandfather had a collection of stamps along with first day covers which was passed over to Charlie- and this fact was known to Sam. When Charlie was looking at his collection, he found the letter which Sam had written to him and that letter gave solid proof of the third level's existence.

Answer 2

Answer:

Charley and louisa are sure that the the third level exists is because of the letter from sam (charley's friend) to author's grandfather on july 1894 which depicts that he was in galesburg of 1890s where he reached throug a train from the third level of grand central station....Hope it helps