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XXIV. — On the Illumination of Light-houses. By Lieut. Thomas Drummond, 
of the Royal Engineers. Communicated by Lieut. Colonel Colby of the Royal 
Engineers , F.R.S. 
Read June 17th, 1830. 
In a former paper which the Royal Society has done me the honour to place 
among its Transactions*, a method of producing intense light is described, the 
object of which is to render visible distant stations in geodetical operations. 
At the conclusion of that paper I ventured to suggest that this method might 
be found useful for other purposes besides that for which it had been contrived ; 
and more especially for the illumination of light-houses. 
Soon after its publication, I received, through my friend Colonel Colby, a 
communication from the Trinity House, under whose jurisdiction and manage- 
ment the greater number of light-houses on the coast of England and Wales 
are placed, intimating the intention of that Corporation to give the method pro- 
posed a fair trial, whenever the apparatus should be brought to such a state of 
perfection as would ensure the steady continuance of the light, while at the 
same time it admitted of being entrusted with safety to the hands of the ordi- 
nary attendants. A good deal remained to be accomplished before this degree 
of simplicity could be considered as attained : nevertheless, the offer of the Cor- 
poration was prompt and liberal ; and, with the assurance that the time and 
labour devoted to this object would not be vainly and unprofitably expended, 
I was anxious to undertake the necessary experiments without delay. 
The survey of Ireland, however, had just been commenced ; and being 
employed on that service, I found it impossible to continue these experiments, 
in the first instance from constant occupation and absence from London, and 
latterly from a long and severe illness, the consequence of a very laborious and 
anxious duty in Ireland. 
During the last winter, however, I was again able to return to this subject, 
* Phil. Trans. 1826, Part III. page 324. 
MDCCCXXX. 3 D 
