 As well as collecting samples of the aegerine granite, rockallite, for later analysis in London, the top of the rock was blown off using a newly developed blasting technique, Precision Pre-Splitting.This created a level area that was drilled to take the anchorages for the light beacon that was installed the following year.Two phosphor bronze plates were chased into the wall above Hall's Ledge, each secured by four 80-tonne rock-anchor bolts; there was no evidence of the brass plate installed in 1955.