 The final season of work in 1843 was spent in fitting out the interior . By then Alan had become chief engineer to the NLB and the final work was undertaken under the supervision of his brother Thomas . The light , which had eight lenses revolving around a four wick lamp with pyramidal lenses above and reflecting prisms below each one , was constructed by John Milne of Edinburgh . The machinery was ready by the beginning of 1844 , but it was seven weeks before a landing could be undertaken on the rock . The lamp was finally lit on 1 February and it shone without interruption for the next 110 years . 
