On display at the Observatory is a large Tesla coil, dubbed "GPO-1", one of a pair which were built in 1910 by Earle Ovington.
Ovington, who would go on to fame as an aviator, ran a company which built high voltage generators for medical X-ray and electrotherapy devices.
In public demonstrations of his generators, the spectacular displays drew crowds.
Ovington designed the Observatory's coil to surpass a coil made by Elihu Thomson in 1893 which generated a 64-inch spark. (
Nikola Tesla had secretly produced much larger sparks in 1899.)
The project caught the attention of an Edison Electric Illuminating Company official, who offered $1,000 if the coil were displayed at an upcoming electrical show in Madison Square Garden, with the stipulation that the machine would produce sparks not less than ten feet long.

The machine, dubbed the Million Volt Oscillator was installed in the band balcony overlooking the arena.
At the top of each hour the lights in the main hall were shut off, and sparks would shoot from the copper ball atop the coil to a matching coil 122 inches away, or to a wand held by an assistant.
The chief engineer of the General Electric Company estimated that the discharges were at least 1.3 million volts.

Ovington, who died in 1936, gave the matching Tesla coils to his old electrotherapy colleague Frederick Finch Strong, who in 1937 donated them to Griffith Observatory.
 The Observatory had room to exhibit only one of the pair.
 By this time the machine was missing parts, so Observatory staffer Leon Hall restored it with the notable assistance of Hollywood special effects expert Kenneth Strickfaden who designed the special effects for Frankenstein (1931) among many other movies.
On display at the Observatory is a large Tesla coil, dubbed "GPO-1", one of a pair which were built in 1910 by Earle Ovington. Ovington, who would go on to fame as an aviator, ran a company which built high voltage generators for medical X-ray and electrotherapy devices. In public demonstrations of his generators, the spectacular displays drew crowds. Ovington designed the Observatory's coil to surpass a coil made by Elihu Thomson in 1893 which generated a 64-inch spark. (Nikola Tesla had secretly produced much larger sparks in 1899.) The project caught the attention of an Edison Electric Illuminating Company official, who offered $1,000 if the coil were displayed at an upcoming electrical show in Madison Square Garden, with the stipulation that the machine would produce sparks not less than ten feet long.
The machine, dubbed the Million Volt Oscillator was installed in the band balcony overlooking the arena. At the top of each hour the lights in the main hall were shut off, and sparks would shoot from the copper ball atop the coil to a matching coil 122 inches away, or to a wand held by an assistant. The chief engineer of the General Electric Company estimated that the discharges were at least 1.3 million volts.
Ovington, who died in 1936, gave the matching Tesla coils to his old electrotherapy colleague Frederick Finch Strong, who in 1937 donated them to Griffith Observatory.  The Observatory had room to exhibit only one of the pair.  By this time the machine was missing parts, so Observatory staffer Leon Hall restored it with the notable assistance of Hollywood special effects expert Kenneth Strickfaden who designed the special effects for Frankenstein (1931) among many other movies.
Griffith Observatory