An Indus Scale

Chapter 5 from Sudeshna Guha's bestselling A History of India Through 75 Objects (2022); the highly-recommended book also includes chapters on ancient Indus artifacts like the dancing girl and the Daimabad bronze.

Tucked away in a case full of weights from Mohenjodaro and Harappa, in the Harappa Gallery of the National Museum is this tiny object, which was described as a ‘measure of length’ by Ernest Mackay, who directed the excavations at Mohenjodaro when this was found. It is a scale, or a ruler, made of shell, and was recovered broken at both ends, from Room 46, Block 18, in the section of the archaeological site designated the DK area. Nine dividing lines and a circle are clearly incised upon the flat surface. A few lines which look like scratches go across the dividing lines.

Linear scales and other small and portable instruments of measure remain rare archaeological finds, especially in South Asia. A tiny bronze rod, 1.5 inches long and with four divisions, which was subsequently found at Harappa is the only other linear scale known from the Indus Civilization. Archaeologists, for example Jonathan Mark Kenoyer, suggest that ‘these measuring devices [...] may have been prepared for some special occasion or elite consumer, but the average person living in these cities probably used other means of measurement’. Mackay knew of the finds of linear scales from Bronze Age Egypt, and so he ordered a cast to be made of the shell scale of Mohenjodaro, to be provided for examination to Sir William Matthew Flinders Petrie, the renowned Egyptologist (1853–1942). The casting of this scale is a one-off in the early scholarship of the Indus Civilization and adds to the historic value of the object as a rare find.

Petrie compared the cast with an ivory scale of Twelfth Dynasty Egypt and declared that ‘the weighted average length of one space’ was 0.2 inches and the ‘mean error of graduation=0.003 inches’. Mackay followed up on the complicated math in Petrie’s description of the Indus scale and stipulated that the divisions were possibly ‘multiple of five’. He stated that ‘the rod is divided upon a decimal system; group of ten divisions were marked off by circles and were halved into sub-groups of five’. The divisions would have needed a very sharp and thin instrument to incise on the shell, and the lines illustrate the incredible precision of the workmanship. Notably, while describing the object, Mackay emphasized that ‘in conjunction with the system of weights, it shows the people of Mohenjodaro to have reached an advanced stage of mental development, with capabilities of precision and mathematical accuracy in thought and work’. Of its several unique features he identified one to be the raw material, which he stated was the best that could have been used;

"[for] it is not liable to warp or crack, nor even to be affected by changes of temperature – if, indeed, such an idea as this last ever entered into the head of the maker. [The] only objection to the use of shell for making measures of length is the obvious one that only short lengths can be procured; but this difficulty could have been obviated by the provision of metal joints."

Shell working is a difficult and intricate task, and during the third millennium bce would have demanded bronze chisels as hard as modern steel saws for breaking the internal columella and interior whorls. As we now know, much of the manufacturing processes happened in specialized workshops, and shells procured from the coastal areas of the Arabian Sea were brought to select centres to be made into artefacts. Objects of shell abound in many sites of the Indus Civilization, and the intricate pieces of inlays and objet d’arts, of which some are simply masterpieces – such as two miniature crocodile heads, distinctive bangles incised with a chevron pattern, and carefully carved large spoons, possibly for libation – demonstrate the very high aesthetic skills of their makers. These shell artefacts, along with the steatite seals, terracotta spindle whorls, beads of various material, baked bricks, cubical weights, and remarkable architectural elements – such as grid-like layouts, parallel streets, wells and bathing platforms, reservoirs (at Dholavira), the Great Bath (Mohenjodaro), and the Great Granary (Harappa), now described as a Great Hall for dyeing – illustrate the careful regard of the Indus craftsmen for exactness and detail.

Significantly, the ‘standardized concept of measurement’, which the Mohenjodaro scale conveys through the decimal system, is not representative of any ‘overarching authoritarian or political force’ as Kenoyer cautions us to note. This is because the ‘basic measurements themselves are at the root of the standardization. [...] the width of hands or the weight of specific types of grains would have been generally uniform throughout the greater Indus valley, and consequently the measures derived from them would have been relatively uniform.’ Kenoyer reminds us of the hand as a cubit unit of measuring length in the Indus Civilization, especially in brick making and construction of buildings and has also carefully demonstrated the exactness of the manufacturing technologies, largely through his studies of the bead-making technology that ‘required the use of precise measurements by craftsmen in order to prepare tools such as saws and drills, as well as the finished beads themselves’. The scale from Mohenjodaro thus provokes enquiries into perceptions of accuracy within the Indus Civilization. Clearly, such perceptions were not guided by the impositions of the political authorities.

The Indus Scale is older than those of the Twelfth Dynasty Egypt through which, as noted above, inferences regarding what it may have been were first derived. The object stirs up questions about Bronze Age knowledge systems, and thereby also coaxes reflections upon the extent to which field archaeology, through which the Indus Civilization is known, allows explorations of the intellectual histories of such non-text worlds.

Bisht, R.S. (2015). Excavations at Dholavira 1989–2005. Archaeological Survey of India. [Unpublished report].
Kenoyer, J.M. (2010). ‘Measuring the Harappan World: Insights into the Indus Order and Cosmology’. In I. Morely and C. Renfrew (Eds), The Archaeology of Measurement: Comprehending Heaven, Earth and Time in Ancient Societies (pp. 106–21). Cambridge University Press.
Mackay, E.J.H. (1938). ‘Household Objects, Tools and Implements’. In E.J.H. Mackay (Ed.), Further Excavations at Mohenjodaro: Being an Official Account of Archaeological Excavations at Mohenjodaro carried out by the Government of India between 1927 and 1931, Vol. 1. (pp. 392–440). Manager of Publications.