39 () LIEUT. DRUMMOND ON THE ILLUMINATION OF LIGHT-HOUSES. 
lights, but the superiority was not much less obvious. I really cannot affix a 
proportion either as to size or brilliancy ; but I should not hesitate to say that 
your light was at least six or eight times as conspicuous ; while in brilliancy, or 
purity, or intensity of light, (for I know not precisely what word to use to 
describe the extreme whiteness,) the superiority was even more remarkable. 
All this which I have been describing was expressed, and appeared to be quite 
as strongly felt by the rest of the company, to the number, I should suppose, of 
five-and-twentv or thirty persons, who were all closely on the watch. 
“ Third comparative Experiment. — The next comparative trial was between 
the French lens and your light. The superiority here was equally undeniable ; 
though the difference in the degree of whiteness was not so remarkable. The 
French light, however, is so nearly similar to that from the seven Argands, that 
the comparison of each of them with your light gave nearly the same results, 
and all equally satisfactory on the score of your discovery. 
“Final Experiment. — The flashes with which the experiments concluded were 
very striking, and might I think be turned to great account in rendering light- 
houses distinct from one another. The revolutions were not effective, and, as 
1 said before, there was no appearance last night of those enormous comets’ 
tails which swept the horizon on the night of the 25th, to the wonder of all 
who beheld them : neither could there be detected the slightest trace of any 
shadow from the light thrown towards us, and I suspect none will ever be 
'een, when the moon, whether the night be clouded or not, is of so great a 
magnitude. 
“ Such is the best account I can give of what we witnessed ; and I need only 
add that there seemed to be amongst the company but one opinion of the im- 
mense superiority of your light over all the others brought into comparison 
with it. 
“ I am, & c. 
“ Basil Hall.” 
The advantage of such a light being fully recognised, attention may now be 
exclusively directed to remove some of those minor obstacles that might render 
its use in light-houses objectionable; and I have great pleasure in adding that 
the Trinity Corporation are desirous that every, facility in their power should 
