no MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 



this system are shown on Plate 53. Fig. A illustrates a simple and widely used 

 light character, .3-second light+2.7 seconds eclipse. In this example the 

 light bums for only .1 of the total period (Hght and ecHpse). Thus, if a 

 ^-foot burner is used (which burning continuously consumes 12 cubic feet 



of gas every 24 hours), an accumulator A-50, of 180 cubic feet gas capacity, 



180 

 will last for X 10= 150 days, from which, deducting for the pilot burner 



and allowing a large margin of safety, the light can be depended upon to 

 run continuously for over 120 days or 4 months. The foregoing readily 

 shows the enormous saving in gas and maintenance effected by those efficient 

 short flashes. 



As seen from Plate 49, the ehtire flashing mechanism is contained within 

 the lantern. 



THB BUOY LANTERN. 



The Panama Canal buoys will all be equipped with sixth order lanterns. 

 This method of dividing lighthouse lanterns into various orders is based 

 upon the focal distance of the optic, that is, half the diameter of the lens 

 at the focal plane as follows : — 



With a I -foot burner of 46 Hefner candle-power (the size adopted for 

 the Panama buoys), the efficiency of the light through the lens will be 400 

 Hefner candle-power visible at a range of about ii| nautical miles. 



Such great candle-powers are obtainable on account of the high intrinsic 

 brightness of the acetylene flame, which, being relatively small in size, 

 permits of almost exact centering at the focus of the lens. Lenses consisting 



