That the Luo Shu appears on Chinese sundials from the seventeenth century has never been documented until now.
This type of sundial did not appear much before 1600 AD. Many replications of this instrument can be found at several museums. The Type B sundial, or equatorial dial, became popular in Europe during the seventeenth century.
One can clearly see the numbers of the Luo Shu in the second ring adjacent to the ring with the eight trigrams. Even numbers are in black, odd numbers are in red. It is perfectly appropriate for the Luo Shu to be used as a motif to mark astronomical instruments that are related to time measurement and space directionality.
Instruments such as the portable sundial help humankind to connect with Heaven. The Luo Shu has a legacy of being related to the calendar, the Pythagorean Theorem, the carpenter's square and the gnomon.
From Science and Civilisation in China, p. i of every volume:
The carpenter's square is no ordinary tool, but the gnomon for measuring the lengths of the sun's solstitial shadows.
The above pictures were taken from Time, Science, and Society in China and the West edited by J.T. Fraser, et al (1986). Another example can be found in Science and Civilisation in China, Vol. 3, p. 308, Figure 134. Please note the editor offers explanations of the markings in each of the rings around the compass but makes no mention of the Luo Shu being present in the second ring. This is the first time this observation has been noted.
Symbols such as the Luo Shu and carpenter's square are frequently used in art and architecture to identify things of political or religious significance such as temples, churches, art, architecture, and astronomical instruments.
My paper, The Secret of the Luo Shu, Numerology in Art and Architecture explains in detail the use of the Luo Shu and related symbols as an artistic motif used by many cultures for over two thousand years.
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