What does tachymetry mean?
Tachymetry is the measurement of velocity by observing both the distance traveled and the time elapsed. It is especially important in surveying, where an instrument called a tachymeter can determine distances quickly and accurately from observations made at one station. By applying the basic relationship between speed, distance, and time, surveyors can calculate the distance to a distant object or the speed of a moving object without requiring a direct chain measurement. The word is consequently associated with precision field measurement rather than ordinary distance measurement. Tachymetry appears in geodesy, engineering, construction, and other technical settings, including modern electronic and optical surveying systems. Although the basic idea is mathematically straightforward, accurate results depend on careful instrument use, calibration, and corrections for environmental and instrumental factors.
nounThe measurement of velocity by observing the distance covered and the time taken, especially using a specialized surveying instrument. It is commonly used in surveying and engineering to determine distances and speeds indirectly.
- The measurement of velocity by determining distance covered in a known interval of time, especially with a tachymeter.
"The survey team used tachymetry to measure the distance across the valley without climbing to the opposite ridge."
"Using tachymetry, the engineer calculated the speed of the train as it passed the survey markers."
"The course taught students how to use tachymetry for rapid and accurate field surveying."
The plural is possible but uncommon; singular usage predominates.
"The report compares tachymetries taken from several survey stations."
Tachymetry turns the simple relationship between distance and time into a surveying superpower.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does tachymetry come from?
The word comes from Greek takhys, meaning “swift” or “fast,” and metron, meaning “measure.” It developed through the term tachymeter, an instrument used to measure distance or velocity indirectly by combining optical observation with measurements of time. The same Greek roots appear in related technical words such as tachymetry, tachymetric, and tachometer. Its broader family also includes words formed from takhys, such as tachycardia and tachyon.
Related word forms
How tachymetry is actually used
The term is mainly technical and is most often encountered in surveying, engineering, and related scientific disciplines. In modern surveying, it usually refers specifically to measurement with a tachymeter.
Easily confused with tachymetry
A tachometer is an instrument that measures rotational speed, whereas tachymetry is the method or practice of measuring velocity from distance and elapsed time.