Regarding the pinhole image, Jing jing ling chi discusses the phenomenon of Pinhole imaging, which Zheng refers to as "small hole imaging" (ε°εζε).
This concept, where light passing through a small aperture forms an inverted image, was known in China as early as the 5th century BC, notably described by Mozi in the Mozi text.
Zhengβs work builds on this historical understanding, exploring how Pinhole imaging works in the context of his broader study of light and optical devices.
However, the book is not exclusively about Pinhole imaging; it covers a wide range of optical phenomena, including the use of concave and convex mirrors, lenses, and other instruments for observing and manipulating light.
The text is structured in a way that combines theoretical explanations with practical applications, reflecting Zhengβs aim to make optics accessible and useful.
It includes illustrations and descriptions of optical experiments, making it a blend of scientific inquiry and technical manual.
While it does not reach the mathematical rigor of contemporary Western optics, it represents a significant effort to synthesize Chinese and Western scientific traditions.
CHINESE OPTICAL KNOWLEDGE
ZHENG FU-GUANG ZHU (1780β1853)
In his 'Jing jing ling chi' (Optical and Other Comments), the property of Pinhole image inversion was demonstrated using the canonical image of a pagoda, below.
Zheng Fuguangβs Jing jing ling chi (ι‘ι‘θ©η‘), written during the Qing dynasty (1644 to 1912), is a significant work on optics, notable for being one of the earliest Chinese texts to systematically explore this field.
The book, whose title can be translated as "Reflections on Mirrors" or "The Subtle Insights of Mirrors," focuses on the principles of geometric optics, including the behavior of light, reflection, refraction, and the properties of lenses and mirrors.
It draws heavily on traditional Chinese knowledge and Zhengβs own experiments, while also incorporating some Western optical concepts introduced through the Jesuit missionaries which I have spoken on.