380 Scientific Proceedings, Royal Dublin Society. 
There is a well-known class of buoy called the Courtenay auto- 
matic whistling buoy in which the motion of the sea sounds a 
powerful whistle or horn and thus assists 
mariners by sound as well as by sight, 
but, inasmuch as these buoys are only 
visible by day, it is satisfactory to know 
that the plan of lighting we are now con- 
sidering can be easily applied to them, so 
that by night as well as by day they may 
be useful warnings to the sailor. A 
simple adaptation of the Courtenay buoy 
enables this to be done. The air tube 
which sounds the whistle is turned at right 
angles to the vertical section of the buoy, 
and the centre of the buoy is thus made 
available for the cylindric tank of the 
burner. 
Cost.—We come now to the important 
question of cost. 
The cost of this system of lighting Fic. 2. 
beacons and buoys is very trifling, the consumption of oil being 
only half a gallon in twenty-four hours. This at the present price 
of oil, say 6d. per gallon, is only 3d. per day of twenty-four hours. 
This expenditure of oilis inclusive of what may appear at first sight 
to be the waste of oil in the constant drip, which as you have seen, 
takes place from the lower receiver of the lamp. ‘This so-called 
waste is, however, of great value in calming the sea in the neighbour- 
hood of the buoy or beacon. It is extraordinary to how great an 
extent a single drop of oil will spread itself over the sea, smoothing 
what would otherwise be broken water; but if desirable to reduce 
the above cost of 3d. per day still further, this drip of oil, instead 
of being allowed to drop into the sea, can be collected by the use 
of the receiver shown in the drawing, and thus be available for 
use again, in which case the 3d. per day would be reduced by 
2d., leaving the total cost only 1d. per day. 
I think it ig evident that the economy of this plan as com- 
pared with the compressed gas system is very great, and that 
the action of the lamp is so simple as to be of easy application. 
