A few weeks ago, we wrote a blog post about the ancient Egyptian and Greek surveyors. Today, we wanted to continue that conversation by including ancient Rome and China. Both were Masters of Surveying and developed their own innovative instruments and methods.
Ancient Roman engineering is world renown. From aqueducts to Roman roads, to big architectural projects like the Colosseum, Roman construction is famous. Roman roads built in England are still in great shape despite the passing of thousands of years and neglect.
Roman engineers didn’t have compasses or maps to guide them while building roads. They almost exclusively used a Groma. The Groma is probably one of the most well-known surveying instruments developed by the Romans.
A Groma surveys straight lines and right angles. The Groma consisted of a vertical staff with horizontal cross-pieces mounted at right angles on a bracket. Lead weights hung vertically from the ends of the cross-pieces.
The surveyor would line the lead weight up with the one in front of it to set a straight line. Magnification wasn’t invented until 1608, so all of Roman surveying was done with the naked eye.
Another significant Roman invention was the Chorobates. This was used as a level. It’s thought to be largely used during construction of aqueducts.
A Chorobates is a wooden bench with a short channel in the middle filled with water and a plumb bob at each end. Also called the Roman spirit level, this instrument was used to find levels between two points.
Significant Innovations from the Chinese
Chinese surveyors and mathematicians are probably most well-known for their invention of the magnetic compass. Most likely invented during the Quin dynasty (221-206 BC), the compass is thought by some to be the most important instrument in surveying history.
The story goes that Chinese fortune tellers used lodestones to make fortune telling boards. Eventually someone realized that the lodestones, a mineral made of iron oxide, always aligned itself in the north-south direction.
The first Chinese compasses were made from lodestones shaved into a spoon shape. The lodestone was shaped so the handle of the spoon would always point south. The pointing needle was set on a square slab with markings for the cardinal points.
In the 8th century A.D., the Chinese replaced the lodestones with magnetized needles.
The Chinese first used their compass to mark constellations and map out important points and boundaries. They started to use them to navigate on ships sometime between 850 and 1050 A.D.
Another contribution to surveying by ancient China is the Sea Island Mathematical Manuel. Written by Liu Hui in 263 A.D., this book contains 9 mathematical problems related to surveying. Liu Hui wrote the Manual in response to a previous text, The Nine Chapters on the Mathematical Art, which Lui Hui thought was inadequate. Liu Hui’s work become its own separate text and was part of the Chinese Royal Academy’s curriculum by A.D. 656.
The Sea Island Manual is filled with detailed instructions on measuring height and distances using right triangle theory.
This manual shows just how theoretically and mathematically sophisticated ancient Chinese surveyors were. Ancient Asian cultures followed the mathematical procedures written in this manual for the next one thousand years.