Work on the foundations for the lighthouse continued until 30 September. A total of 296 charges were used to remove of rock and Stevenson believed that the rock was so hard that the effort involved was four times that required for boring Aberdeenshire granite. The work went well but by the end of the second season, no blocks had yet been laid. However, between April 1839 and June 1840 4,300 blocks had been fashioned, the stone donated by the Duke of Argyll from quarries on Mull. The roughly hewn rock was taken to Hynish where the blocks were hammered and chiselled into shape. The largest weighed over , the smallest and the precision required meant that a single block could take 320 worker-hours to complete.