The Haʻikū Stairs, also known as the Stairway to Heaven or Haʻikū Ladder, is a steep hiking trail on the island of Oʻahu. The trail began as a wooden ladder spiked to the cliff on the south side of the Haʻikū Valley. It was installed in 1942 to enable antenna cables to be strung from one side of the cliffs above Haʻikū Valley to the other. A building to provide a continuous communication link between Wahiawā and Haʻikū Valley Naval Radio Station was constructed at the peak of Puʻukeahiakahoe, elevation about 2,800 feet (850 m). The antennae transmitted very low frequency radio signals from a 200,000-watt Alexanderson alternator in the center of Haʻikū valley. The signals could reach US Navy submarines as far away as Tokyo Bay while the submarines were submerged.

A group of Japanese schoolgirls marching in formation during a school visit to the third regiment to experience the soldier's way of life. (Photo by Fox Photos/Getty Images). Circa 1938

“The technology was designed to address the risk associated with head-on or nearly head-on motorcycle collisions, which account for a large percentage of motorcycle crashes. The airbag was designed to deploy during a severe frontal collision in which a rider could be thrown forward from the motorcycle. Once deployed, the airbag stands upright in front of the rider to help absorb the rider’s kinetic energy prior to leaving the motorcycle”. – Ohio.Honda.com

Photo: Honda Motor Co., Ltd.'s world's first production motorcycle airbag system is introduced at a press conference at Honda's HQ on September 8, 2005 in Tokyo, Japan. The motorcycle airbag system to be installed to lessen the injuries of the rider is comprised of the airbag module that include the airbag and the inflator, crash sensors that monitor acceleration changes and an ECU that performs calculation to determine when a collision is occuring. (Photo by Junko Kimura/Getty Images)

A British policewoman chasing after a group of naked street boys by the Serpentine in Hyde Park, London. (Photo by Reg Speller/Getty Images). 1926

A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.