A FURTHER stage towards precision in the dating of the prehistoric civilisation of the Indus valley is marked by Mr. Ernest Mackay's letter to the Times of Aug. 27. Mr. Mackay records the discovery at Mohenjo-daro of a fragment of a steatite vase which bears exactly the same intricate and very unusual pattern as a double vase of the second period of Susa. It was found at a depth of 28 ft. below datum, very little above water-level in the soil when the river is at its lowest. The inference that it was an import from Elam is borne out by the material of the fragment, a greenish-grey steatite identical with that of the Susa II. double vase. A conservative estimate for the dating of Susa II. would place the Mohenjo-daro find at about 2800 B.C. On the other hand, Mr. Mackay points out that the seal, of undoubted Indian workmanship, found by Dr. H. Frankfort at Tell Asmar, is inscribed with animals which occur commonly on seals and sealings at Mohenjo-daro (although as yet only two cylinder seals have been found) and can be contemporaneous only with the upper levels of that site, occurring at some three to seven feet below datum. This, on the basis of Dr. Frankfort's dating of the Tell Asmar seal, would give a dating of 2500 B.C. for the upper levels at Mohenjo-daro—a reduction on the previous provisional dating. It would thus appear that between the lower levels, 28 ft. below datum, and the upper levels, contemporary with the period of the Tell Asmar find, some three hundred years elapse—a conclusion to which Mr. Mackay states that he already inclined on other grounds.