I20 MARINE LIGHTING EQUIPMENT OF THE PANAMA CANAL. 



Referring to page io8, under "The Flasher," we do not see that there is any new 

 principle emboided in this flasher, as it operates along exactly the same lines as 

 the Pintsch chamber, with permanent magnets substituted for coil springs to hold 

 the valves tight against their seats. As none of these flashers have been in service 

 in this country, so far as we know, for over four years, and as the Pintsch chamber 

 with coil springs has been in use over twenty years, it is hard to make a reliable com- 

 parison. We are informed, however, by the government lampists that when the 

 dark period, as well as the light period, is very short, the constant shock of the arma- 

 ture striking the magnetized valve seats tends to demagnetize them and change 

 the characteristic, which is to be expected, for it is a well-known fact that a perma- 

 nent magnet becomes demagnetized if subjected to repeated hammer blows. 



The necessarily small gas capacity of compressed acetylene buoys and beacons 

 inspired of necessity the quick flash with relatively long, dark intervals, by which 

 90 per cent of the gas is claimed to be saved. We believe, however, that this type 

 of characteristic does not receive general favor by navigators and those to whom 

 aids in navigation are of most usee We believe the general preference to-day among 

 mariners is for equal periods of light and dark. 



The Panama type of buoy set with fixed light would have a life of less than a 

 month, we believe, or, flashing equal periods, about seven weeks, whereas the 

 Pintsch type of buoy under similar conditions would burn for three months with a 

 fixed light and for six months with equal periods. 



The Pintsch buoy is also adjustable within long ranges of light and dark and 

 is suppUed in single or multiple characteristic. 



It might not be out of place to call attention to the type of lantern shown, 

 which we think is weak. The vertical astregals have neither the strength nor rigidity 

 of the helical bars with triangular storm panes. The light lost by the helix crossing 

 the projected light beam is never over 10 per cent and at a short distance cannot 

 be detected. The loss of light through absorption in the reflecting prisms equals 

 that hidden by a helical astregal. 



In conclusion, we believe that compressed acetylene as a method of lighting 

 under certain conditions may be very advantageous. The Panama Canal Com- 

 mission, we know, considered all the various systems of lighting before adopting 

 this system. 



Mr. Pattison (Communicated) : — I wish to state that I have read the written 

 discussions of my paper with much interest. 



Mr. Beyer's communication covers very thoroughly the general nature of the 

 various aids to navigation to be used throughout the canal. 



As to the communication from Mr. Gillis I wish to take exception to some of 

 the statements he makes. In the sixth paragraph of the first page, he presents 

 figures showing comparison in light power of acetylene not dissolved in acetone, 

 and acetylene dissolved in acetone. 



Acetylene dissolved in acetone actually gives a better light than acetylene not 



