To his amazement, the barley visible indentations generated a vague sound when the paper was pulled back beneath the stylus. In December 1877 Edison unveiled the tinfoil phonograph, which replaced the strip of paper wrapped in tinfoil. Many people would not believe what they were hearing including a leading French scientist who declared it to be a trick device of a ventriloquist. The public"s amazement was quickly followed by universal approval. Edison became famous all around the world and was dubbed the Wizard of Menlo Park, although ten years passed before the phonograph was transformed form a laboratory curiosity into a commercial product. His most famous and most commonly used invention is the incandescent light bulb. American scientists including Samuel Langley needed a highly sensitive instrument that could be used to measure minute temperature changes in heat emitted from the Sun"s corona during a solar eclipse along the rocky mountains on July 29,1878. To please those needs Edison invented a "microtasimeter" employing a carbon button. This was a time when great advances were being made in arc lights so that electricity could be used for lighting in the same fashion as with small, individual gas "burners". The basic problem seemed to be to keep the burner, or the bulb, from being consumed by preventing it from overheating. Edison thought he would be able to solve this by coming up with a microtasimeter-like device to control the current. He proclaimed that he would invent a safe, mild, and inexpensive electric light that would replace the gaslight. Inventors had been attempting to devise the incandescent light bulb for fifty years, but Edison"s reputation and past achievements commanded respect for his bold prediction. As a result, a group of leading financiers, including J.P. Morgan and the Vanderbilts, established the Edison Electric Light Company, and advanced him $30,000 for his research and development.