ii8 MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 



Acetylene (purified but not dissolved in acetone), 40 candles per foot. 



Acetylene (dissolved in acetone, Presto-lite tank), 30 candles per foot. 



Pintsch gas compressed to twelve atmospheres, flat flame regenerative lamp, 

 12 candles per foot. 



Pintsch mantles, large mantles burning at 2 pounds pressure, 60 candles per 

 foot. 



Pintsch mantles, small mantles burning at i pound pressure (buoy type), 40 

 candles per foot. 



Intensity per square inch of projection: acetylene, 32 candles per square inch; 

 Pintsch mantles, 80 candles per square inch. 



The spherical form of mantle is more advantageous when used with optical 

 apparatus than a flat flame, as it approximates a point source and gives a smaller 

 divergence to the beam ; it has an even horizontal intensity in all directions, whereas 

 a flat flame loses at least 20 per cent when set edgewise. 



Actual photometric comparison of candle-power through 200 mm. lense, 

 measured on 150-foot radius, shows: — Pintsch mantle, 140 candles; J foot-acetylene, 

 70 candles. 



We note also that the writer states that the carbide type of buoy has been aban- 

 doned for the new type of dissolved acetylene. We do not know to just what 

 country he refers, for the Canadian Government, as we understand it, uses nothing 

 but carbide buoys. It is also true that the United States Government is now very 

 much interested in the carbide buoy, and such a buoy, with a flashing hght and 

 actual gas consumption of 1 1 feet per hour, ran for over 420 days in New York Bay. 

 Another of this type, of different manufacture, with a fixed hght, consuming 2 

 feet per hour, ran for nine months in Limon Bay, Panama. We believe it is also 

 true that with proper purification generator acetylene gives higher efficiency than 

 the dissolved type, the latter invariably carrying a small amount of acetone to 

 the burner, which is borne out by the writer's statement on page 107, in "Upkeep 

 of Accumulators." 



In " Description of the System Adopted," on page 102, we note that the writer 

 cites, amongst other examples, Ambrose Channel. This channel is lighted by a 

 combination system of buoys, and the largest buoy and the furthest out to seals 

 the carbide buoy. This flashes five seconds light and five seconds dark and has a 

 light source of about 75 candles in a 375-millimeter lantern. There are two en- 

 trance, two exit and two turning-point buoys of the compressed acetylene type 

 flashing .4 second light and .8 second dark with a hght source of 40 candles in 375- 

 millimeter lanterns. There are also 12 Pintsch mantle buoys burning with a fixed 

 light of 30 candles source in 200-millimeter lanterns. It might be interesting to 

 note comparison of the gas in these buoys. 



The gas in the compressed acetylene buoy, flashing .4 second light and .8 

 second dark, 40 candle-power, 300 feet per month, costs $4.50. 



The Pintsch buoy, fixed light, 30 candle-power, 630 feet per month, costs $3.30 

 per month with a plain burner and fo.45 per month with mantle burner. 



