Thomas Alva Edison (1847-1931), American inventor, seen here, in 1888, after 5 days and 5 nights of continuous work improving his phonograph (visible before him). At the age of 23, Edison invented a stock ticker which he sold to a Wall Street firm for 30,000 dollars. With this, he founded a firm of engineers which turned out inventions such as waxpaper and the mimeograph. In 1876 he set up a research laboratory in Menlo Park, New Jersey. Here he invented the phonograph, improved the telephone and, after thousands of experiments, succeeded in making a practical lightbulb. During his lifetime Edison filed a total of 1069 patents, a record no other inventor has ever approached.