MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 117 



Pacific entrances. The beacon and gas buoy lights will be about 400 candle- 

 power. 



To eliminate the possibility of confounding the lights with one another and with 

 lights on shore, all range lights, beacons and buoys will have individual character- 

 istics formed by flashes of light and dark intervals. 



In the electric lighted towers the burner is so arranged that, when the lamp in 

 place burns out, it drops out of focus and a reserve lamp drops into its place, thus 

 minimizing the danger of a light being extinguished. This mechanism is operated 

 by a shunt and series coil, the latter of which is thrown out when the light goes out, 

 thus allowing the shunt coil to operate a lever and so replace the burnt-out globe 

 with a new one. 



Aids to Navigation. — The number and type of aids to navigation employed in 

 the project for lighting and buoying the canal is as follows : — 



1 harbor light (West Breakwater) lighted by incandescent oil vapor lamps or 

 acetylene. 



14 range towers, hghted by electricity. 



18 range towers lighted by acetylene gas. 



46 beacons lighted by electricity. 



3 beacons lighted by acetylene gas. 



59 gas buoys lighted by compressed acetylene dissolved in acetone. 



100 spar buoys (unlighted). 



2 gas buoys lighted by acetylene (channel to |terminal docks and dry dock at 

 Cristobal) . 



7 nun buoys unlighted (channel to terminal docks and dry dock at Cristobal) . 

 At the present writing (November, 191 2), contracts have been entered into only 

 for 57 gas buoys lighted with compressed acetylene dissolved in acetone. 



Mr. H. a. Gilus, Associate (Communicated): — Referring to Paper No. 4, 

 "Marine Lighting Equipment of the Panama Canal." 



This paper is one of the most interesting presented for some time on the subject 

 of marine lighting and I think the thanks of the Society are due Mr. Pattison. 

 However, I believe Mr. Pattison will be glad to have us criticize the paper and cor- 

 rect any mistakes apparent to us. We, therefore, would respectfully call attention 

 to the following: — 



On page loi, the question of reliability of mantles is spoken of, or rather the 

 unreliability of the same. The average life of mantles on buoys, taken from over 

 2,000 buoys, is three months. In many cases, these mantles have run from 250 

 to 400 days. 



I also note the question of loss of lighting power due to compression. The loss 

 of candle-power due to compression is about 10 per cent. 



As to the quality of lighting, the Pintsch mantle and the acetylene flame have 

 almost exactly the same spectrum. 



As to lighting power, it will be of interest to know the following : — 



