Farmer’s Incandescent Lamp, 1859.
This experimental platinum lamp was made by Professor Farmer and several of them lighted the parlor of his home in Salem, Mass.
FURTHER ARC LAMP DEVELOPMENTS
During the ten years, 1850 to 1860, several inventors developed arc lamp mechanisms. Among them was M. J. Roberts, who had invented the graphite incandescent lamp. In Roberts’ arc lamp, which he patented in 1852, the lower carbon was stationary. The upper carbon fitted snugly into an iron tube. In the tube was a brass covered iron rod, which by its weight could push the upper carbon down the tube so the two carbons normally were in contact. An electro-magnet in series with the arc was so located that, when energized, it pulled up the iron tube. This magnet also held the brass covered iron rod from pushing the upper carbon down the tube so that the two carbons were pulled apart, striking the arc. When the arc went out, the iron tube dropped back into its original position, the brass covered iron rod was released, pushing the upper carbon down the tube until the two carbons again touched. This closed the circuit again, striking the arc as before.
Roberts’ Arc Lamp, 1852.
The arc was controlled by an electro-magnet which held an iron tube to which the upper carbon was fastened.
Slater and Watson’s Arc Lamp, 1852.
Clutches were used for the first time in this arc lamp to feed the carbons.