Thomas Alva Edison Is One Of The Most Well-known Inventors In History. He Is Most Famous For Inventions Like The Phonograph - The Motion Picture Camera - And The Light Bulb. However - Even Edison Failed In A Few Attempts At Invention - Namely In Trying To Develop A Better Way To Mine Iron Ore During The Late 1880s And Early 1890s. He Was Tenacious In His Attempts To Find A Method That Worked - But He Eventually Gave Up After Having Lost All The Money He Had Invested In Iron-ore Mining Projects. In This Context - The Word Tenacious Means