This work is in the public domain in its country of origin and other countries and areas where the copyright term is the author's life plus 100 years or fewer.
You must also include a United States public domain tag to indicate why this work is in the public domain in the United States.
{{Information |Description=The oldest known illustration of an endless power-transmitting chain drive. This was illustrated in 1092, during the Song Dynasty, by the Chinese engineer Su Song in his book ''Xinyi Xiangfayao''. It was called the "celestial la
You must also include a United States public domain tag to indicate why this work is in the public domain in the United States.
