Somato (a kind of a garden lantern) (走馬灯)
Somato is a kind of a garden lantern, which is crafted to show a revolving shadow picture with its inside and outside frames. Somato is also called a revolving lantern. It debuted in the middle of the Edo period as a summer night entertainment, and it is a word to symbolize summer in the haikai (Japanese 17-syllable verse).
Recently, somato has come to be used in the words to describe the flashback of one's lifetime memory, such as somato phenomenon (a flashback phenomenon) and somato experience (a flashback experience), which is said to be experienced by a dying person --- or which a near-death experiencer says he (or she) saw. It becomes rare for the public to see the real somato, so the word somato is often misunderstood to indicate the phenomenon itself.
Mechanism
Basically, the mechanism of a somato is the same as that of shadow picture play. The source of light is a candle --- at present, an electric light is more common for safety --- and the outside frame has a paper screen. Pictures of a human or a horse cut out from paper are stuck on the axle of the inside frame.
The shadow picture's automatic revolving owes to the invention on the inside frame structure. The axle, attached to the frame, has a pinwheel on itself, and the pinwheel spins from the ascending air current, caused by the air heated by the candle. The wind from the pinwheel revolves the inside frame on which the pictures are stuck.
Originally, somato was an inconspicuous entertainment --- after all, it is just a shadow picture play --- but today, some somato show shadow pictures of vivid colors made from colored cellophane paper.