 Soon up to 95 blocks a day were arriving from Hynish , although the weather continued to play its part . During the summer of 1840 the steamer was unable to reach the reef for fourteen consecutive days , and on another occasion no landings were possible for seven weeks and supplies began to run low . When work ceased again in the autumn , 800 tons of granite standing 8 feet 2 ins ( 2 @.@ 5 m ) high stood on Skerryvore , and up to 80 craftsmen continued to labour on the blocks at Hynish all winter . The first three courses of the base are of hard Hynish gneiss , the remainder are granite from the Ross of Mull . 
