for the purposes of Illumination in Lighthouses. 43 



seemed destined to share that fate which too frequently befalls 

 British inventions that are beyond the sphere of individual en- 

 terprize. 



In the year 1825, the Engineer of the Northern Lighthouse 

 Board went to Paris, and brought over to Edinburgh one of the 

 compound lenses as manufactured by M. SOLEIL. Although this 

 invention had been ascribed to another, it was no slight satisfaction 

 to find that it had been distinguished by the approbation of the 

 most eminent French philosophers. It had occupied the atten- 

 tion of the Institute itself; and after repeated trials, and a careful 

 comparison with the large parabolic reflectors of M. LENOIR, 

 thirty-one inches in diameter, and certainly not inferior to any ma- 

 nufactured in this country, the Commissioners of Lighthouses for 

 France, consisting of mathematicians, civil engineers, and offi- 

 cers of the navy, have adopted the compound lens, and the com- 

 bination of lenses and mirrors, as a new system of illumination ; 

 and a definitive arrangement has been made for bringing it into 

 immediate operation on the English Channel, the Bay of Bis- 

 cay, and the Mediterranean Sea. 



But notwithstanding all this testimony in its favour, the com- 

 pound lens has never yet been put to a public trial in Scot- 

 land. In the course of last winter, it was carried to the Tower 

 of London, and exhibited to a number of gentlemen distinguish- 

 ed by their rank and talents ; but it was exhibited as a foreign 

 invention, and some of those who witnessed its effects transmit- 

 ted descriptions of it as such to the newspapers of Edinburgh, 

 where it had long before been described, in two widely circu- 

 lated works. Another of these lenses was brought from France 

 as a Burning Instrument ; and both it and the Compound Lens 

 purchased by the Engineer to the Lighthouse Board, have been 

 exhibited as a French contrivance in our own University. 



Under these circumstances, I resolved to address myself direct- 

 ly to the Commissioners of the Northern Lighthouses ; and the 



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