ON LIGHTHO USE CHA RA CTERIS TICS. 4 1 7 



has been doing this for a month, and shows no 

 signs of wear. Indeed, there is no part of the 

 machine which is liable to wear in the course of 

 years regular service in a lighthouse. I refer to 

 this machine at present, because it has been supposed 

 that the plan of mechanism used in the Holywood 

 Bank, the Garvel Point, and Cardross Lights that 

 is, a mechanism producing eclipses by revolving 

 screens, and therefore applicable only to light 

 without azimuthal condensation is the only 

 mechanism which can practically produce the 

 groups of eclipses at the speed necessary to carry 

 out this method of giving characteristic qualities to 

 fixed lights. The use of gas in lighthouses, 

 whether for smaller lights visible to a distance of 

 four or five miles, or for any more powerful lights 

 such as the splendid lighthouses of Tuskar and 

 Houth Bailey, is admirably adapted for the quickest 

 systems of eclipses of from one half to three 

 seconds' duration for giving distinctive character, 

 although it has not been taken advantage of in 

 this respect except in the small Craigmore Light in 

 Rothesay Bay by Mr. Mortimer Evans. 

 VOL. in. E E 



