206 Biographical Sketch of the late 



tinction among lights, a matter of the utmost importance in 

 narrow seas, where many lights are visible at once. He was 

 the inventor of two useful distinctions — the intermittent and 

 flashing lights, for the latter of which he received from the 

 late King of the Netherlands a gold medal, as a mark of his 

 Majesty's approbation. In the first of those distinctions the 

 light is suddenly obscured and as suddenly revealed to sight, 

 at unequal intervals of time, in a manner which com- 

 pletely distinguishes it from the ordinary revolving light, 

 which from darkness gradually increases in power till it 

 reaches its brightest place, and then gradually declines until 

 it is again obscured. The flashing light exhibits, by means 

 of a rapid revolution of the frame which carries the lamps 

 and a peculiar arrangement in their position, a sudden flash 

 of great power, once in five seconds of time. 



But while his reputation as an engineer naturally rests 

 chiefly on his great work of the Bell Bock and his im- 

 provements in the illumination of lighthouses, he is by no 

 means without other claims to be remembered. Besides his 

 official duties, he took a considerable share in the general 

 engineering of his day, and acted on many occasions in con- 

 junction with Rennie and Telford, and afterwards with 

 Messrs Walker and Cubitt, with all of whom he ever main- 

 tained a friendly intercourse. Soon after the peace in 1815 

 the public mind was naturally directed to the improvement 

 of our internal resources, which the long continuance of the 

 continental war had thrown unduly into the shade. Roads, 

 bridges, harbours, canals, and railways, soon became topics 

 of public attention and general interest ; and my father's 

 known sagacity and energy rendered him a useful adviser 

 on many of those subjects. In the course of his professional 

 life he designed and executed several important bridges, such 

 those of Stirling, Marykirk, Annan, and the Hutcheson 

 bridge over the Clyde at Glasgow. The beautiful approach 

 to the City of Edinburgh from the east, by the Calton Hill, 

 was designed by him, and executed under his direction ; and 

 I mention this the more willingly, as many of our citizens are 

 not aware to whom we owe this splendid entrance to our 

 " own romantic town." He also surveyed and traced the 



