Coming to auction this week is a small notebook kept by Thomas Edison, in which he penciled his lab notes regarding experiments he was conducting to find an alternative source for rubber. Edison had been asked by auto & tire tycoons, Henry Ford and Harvey Firestone, to figure out if rubber could be produced from anything other than a rubber tree, which did not grow in the U.S. and was becoming expensive to import. Edison duly tested thousands of plants, finding at least one possible substitute in Goldenrod weed. But the great scientist and inventor died in 1931 while still at work on the problem. This notebook, containing 117 pages in Edison's hand, records his rubber experiments between Oct. 24, 1927 and Jan. 9, 1928. It is expected to bring $15,000-25,000 at an auction in Philadelphia on Thursday. Most of Edison's lab notebooks are held by the Thomas Edison National Historic Park in West Orange, New Jersey.