MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 109 



with the valve seats and to produce the desired instantaneous cut-off. The 

 gas outlet now remains open until the total gas quantity has been consumed 

 in the main burner, whereupon the outlet closes and the inlet opens, remain- 

 ing open until a similar quantity of gas accumulates within the flasher, when 

 the cycle of operations is again repeated. Thus the light and dark intervals 

 alternate automatically and produce a uniform flashing light. The pressure 

 of the gas flowing from the flasher to the burner does not vary during the 

 entire light period, regardless of the duration of such period. In the older 

 makes of flashers, the gas enters the burner at a low pressure which gradually 

 rises to the maximum and falls again toward the end of the flash, thus wasting 

 gas and making it difficult at long ranges to determine exactly the charac- 

 teristic of the light. 



LIGHT CHARACTERS. 



The principle of the flashing light as a valuable navigation signal has 

 been taken advantage of in the highest degree by designing the new flasher 

 to consume the least possible amount of gas per flash and to make the dark 

 intervals when no gas is being consumed as long as is consistent with effi- 

 ciency. It is naturally of the utmost importance for the safety of navigation 

 that the light character, i. e., the ratio between light and eclipse, after having 

 once been fixed must not vary in the slightest degree. 



Nearly all lighthouse authorities agree that flashes of short duration 

 followed by relatively short, dark periods are much more distinctive and 

 efficient than long flashes, and this view is borne out by the fact that, of the 

 thousand or more dissolved acetylene lights in operation throughout the 

 world, the majority are adjusted for short flashes. Of the light characters 

 adopted by the army engineers for the lights on the Panama Canal, the 

 flashes do not in any instance exceed 2 seconds' duration, and the majority 

 will be set to .3 of a second. The new flasher, although designed especially 

 to suit short flashes, may easily be adjusted to give flashes of any desired 

 length. 



The flasher is easily and rapidly adjusted by means of accessible screws. 

 Referring to Plate 50, the two caps, 23 and 25, serve to protect the adjusting 

 screws of which 25 is for adjusting the length of the dark interval, and 23 

 for adjusting the length of the light period. Withal, the new flasher is 

 exceedingly simple in principle of operation, and although sensitive it can 

 withstand the most severe strains and jolts of the heaviest sea without 

 variation. 



Some typical examples of light characters as used in conjunction with 



