glossary of terms in map history



“Geodesy” (from the Greek: lit., “earth division”) was coined by learnèd Renaissance mathematical practitioners for all applications of geometry to the observation and measurement of land, esp. property mapping and other forms of place mapping. The sense that geodesy was a universal (Platonic) practice of reducing the earth led it to also be used after ca. 1670 for the more complex forms of surveying used to measure the size and shape of the earth. Regional practice then split. In central and eastern Europe, “geodesy” has retained its universality, so that modern commentators have had to draw pragmatic distinctions between “higher” geodesy (newer, complex surveying) and “lower”/“lesser” geodesy (older, simpler). French and then British practice in the eighteenth century largely restricted “geodesy” to the measurement of the earth, discarding the original meaning. “Geodesy” is thus ambiguous:

¶ geodesy (1)

The measurement and observation of land, i.e., the original, early modern meaning of “geodesy,” which has come to be called “lower geodesy.” It is nonetheless an idealization that embraces several different mapping modes.

¶ geodesy (2)

The universal practice of measuring the earth—of surveying broadly construed—from simple property mapping to the measurement of the earth’s size and shape, regardless of technical or conceptual variations. Its continued use is a major support of the ideal of cartography.

geodesy (3)

The mode of measuring the size and shape of the earth. This restricted usage has dominated in both French and English since the eighteenth century, and has been dominant too among the modern natural sciences (CIH, 179; MHT, ch.2). Geodesy has developed along two distinct but interrelated lines of practice:

  • mathematical or geometrical geodesy, entailing the measurement of the earth’s dimensions in conjunction with both astronomy and official territorial mapping projects;

  • dynamic or physical geodesy is the study of the earth’s constitution and gravitational field and so aligns with the fields that coalesced as geophysics in the nineteenth century.