What did Philip b. downing invent?
The credit of inventing the protective public mailbox(letter-box) goes to the Philip B. Downing, who was from Boston, Massachusetts, had been awarded a U.S. patent(No.462,093) for animprovement to the street letter (mail) box on Oct. 27, 1891.http://www.briskinfo.com/inventions/who-invented-street-letter-drop-mailbox.html