The first of five clues. Each one below gives a little more away.
The first of me was installed before cars existed, and it exploded.
I was invented for horses.
My middle colour was added later, and there was an argument about it.
In Japan the go signal is officially called blue.
Red, amber, green, on a pole.
Traffic Light
The first one stood outside Parliament in 1868, lit by gas and worked by a policeman's lever. It blew up within weeks, injured the constable, and the idea was abandoned for forty years.
The first stood outside the Houses of Parliament in December 1868, decades before cars, to protect pedestrians from horse traffic. It was gas-lit, worked by a constable pulling a lever, and it exploded within weeks, injuring the man operating it; the idea was dropped for forty years. Electric signals returned in Ohio in 1914, and amber was added in Detroit a few years later to solve the problem of the abrupt switch. In Japan the go light is legally described as blue, a holdover from older colour vocabulary, so the lights there are made a slightly bluish green.
Reading five clues at once is not the game. In the real thing they arrive one at a time and every wrong guess costs an hour. Play mystery #48 · today's mystery · the vault
Previous: mystery #47. Next: mystery #49. Or try #13, #14, #15, #16, #17, #18.