504 HYDROGRAPHICAL SURVEYING [chap. xxi. 



above the lantern, and where the observer is screened from the 

 glare and reflection of the lantern. 



Most light vessels have a watch -buoy rehably moored a short 

 distance from them. This fact can often advantageously be 

 made use of when recovering a position, etc. 



In the United Kingdom there is generally to be found at 

 least one trained signalman on board each Ughtvessel, and a 

 megaphone is included in their equipment. 



By day, when anxious to observe a lightvessel at the farthest 

 possible distance, the situation can often be saved by making 

 an extra amount of smoke from their galley funnel at a pre- 

 concerted time, where it would be undesirable, owing to passing 

 vessels, to hoist any flags on board the Ughtvessel. 



SECTION XXII. 



EMPLOYMENT OF BOATS FOR SOUNDING AND AS MARK 



BOATS. 



Boats can be usefully employed in fine weather to examine 

 particular areas where desirable, for which purj)ose it should 

 not be necessary to render them dej^endent for "fixing " upon 

 the position of the ship when at anchor, for the ship will gener- 

 ally be requu'ed to be engaged more advantageously in other 

 dii'ections. 



In order to facihtate fixing by station pointer with the beacons 

 within the area to be examined by the boats, it may be neces- 

 sary to lay out one or more additional temporary beacons, 

 or mark boats, in previously selected spots, where a reUable 

 fix can be obtained when dropping them or visiting one of the 

 original beacons if necessary for this purj^ose, when the new 

 beacon may be " shot up." 



When using a mark boat, it is often a good plan to both drop 

 and weigh the moorings from the ship, passing the upper end 

 of the moorings to and from the boat whilst the ship obtains 

 the fixing angles. 



One mechanically j^ropelled boat or two, if available, can 

 often, under favourable conditions of weather, be employed 

 sounding, keeping in company with the ship on parallel Unes 

 at some previously assigned distance, the boats being dependent 

 u2:)on the ship for fixing. 



