454 Report of Meetings. By the President. 



and two on tlie Fame. That on the Longstone was erected in 

 1826, is 85 feet high, and is furnished with a Eevolving Light 

 on the Dioptric or Eefracting System. The duration of each 

 flash, which is visible 18 miles from a ship's deck, is 7 seconds. 

 It suddenly appears at almost full power, and suddenly dis- 

 appears for 23 seconds, — thus there is only one flash every half 

 minute. 



On the Fame the High Lighthouse was erected in 1766, is 43 

 feet high, and has a Eevolving Light on the Catoptric or Eeflect- 

 ing System, visible 15 miles. 



The duration of the flash at this lighthouse was the same as 

 the Longstone up to August 1st 1884, when it was changed, 

 showing 2 white flashes and 1 red every 20 seconds, which 

 gradually increase and decrease in intensity, only remaining at 

 full power for a short time. It is interesting to know that at 

 both lighthouses, during the period that the light is not visible, 

 it is not lost to the mariner, but is concentrated in the beam 

 that is seen, thus making it at the Longstone five times as 

 powerful as a fixed light. 



The Low Lighthouse on the Fame is an octagonal tower, 27 

 feet high, built in 1810, which shows a fixed light visible 12 

 miles. Colza oil is used for all the lights. 



To the Lights a useful auxiliary is the Fog-horn, which, by 

 special permission of the Trinity Board — through the kind appli- 

 cation of Mr Benjamin Morton, Trinity Superintendent, Sunder- 

 land, to whom I am indebted for much useful information — was 

 sounded several times. 



To fog-enshrouded mariners, as I can testify from personal 

 experience, any sort of noise is welcome save that of breakers on 

 a lee-shore ; but, intrinsically considered, the roar of this Fog- 

 horn is of an unmusical, depressing, and unearthly character. 

 It is managed thus : air is compressed by an air-pump worked 

 by caloric engines, and delivered into a receiver at a pressure of 

 25lbs. per square inch, whence it passes into the inner cylinder. 



The sound is produced by an apparatus of American invention 

 called a Syren, which consists of two metal cylinders fitting 

 closely one inside the other, the inner cylinder being fixed, and 

 the other, which is about a foot high and nine inches in diameter, 

 revolving round it. Both cylinders are pierced with 24 slits 

 about 2 inches long by 2-lOths of an inch broad. The outer 

 cylinder is made to revolve at the rate of 20 revolutions a second. 



