TRANSACTIONS OF SECTION Q. 883 



flashing system is that introduced by Admiral Colomb, which consists of ten 

 figures, represented by short and long flashes, thus : — 



1 . 2 . . 3 . . . 4 . . . . 5 



6 7 ■ 8 . 9 . . . . 



The present flashing, occulting, intermittent, and revolving lights are capable 



of performing the services required by a slight alteration in the clockwork to give 



the necessary division of time, thus : — 



A short flash, 1 second ; an interval between two figures, C seconds ; and an 



eclipse of nine seconds after each complete signal, followed by a steady light for the 



remainder of the 60 seconds. 



Example. — To flash a light the number of which is 3,724 would occupy 



39 seconds, and leave a bright light 21 seconds, the whole to occupy one minute, 



thus: — 



Seconds 



Eclipse 1 



Fig. 3 5 



Eclipse 3 



Fig. 7 5 



Eclipse 3 



Fig. 2 3 



Eclipse 3 



Fig. 4 7 



Eclipse 9 



Bright light 21 



60 



Seconds 

 No. 1111 would be the shortest, occupying only . . 23 



Bright light 37 



60 



Seconds 

 No. 5555 would take the longest time to flash, viz., . 65 



leaving — 

 Bright light 5 



60 



This is the extreme range, and the whole can thus be performed in one minute, 

 and the light to repeat this revolution every minute during the night. 



In fog the author proposes that the numbers be given by a siren every minute, 

 such siren to be confined strictly to lighthouses and light-vessels, and prohibited 

 in the mercantile marine. 



In adopting this system the mariner will become acquainted with the flashing 

 system, and thus lay the foundation of an international flashing signal system for 

 the mercantile marine, so much needed. The author believes that 999 sentences 

 selected from the Commercial Code Book would be ample for all practical 

 purposes. 



2. On an Automatic Gem- separator. 

 By William S. Lockhart, M.I.G.E., M.I.M.E. 



The separator described was devised for the purpose of selecting precious stones 

 from the worthless gravel with which they are associated without the intervention 

 of hand-picking as now practised, thus avoiding the danger of loss by theft and 

 other disadvantages. In South Africa, Burma, Siam, Ceylon, and other parts of 

 the world the systems of washing vary to some extent. The earlier stages of 

 these processes would take too loug to describe, but all systems resolve themselves 

 finally into the picking over of a concentrated deposit of clean washed gravel for 

 the gems it may contain, and it is at this point that the separator comes in to 

 perform what has hitherto been done by hand. When it is realised that the 



3 L 2 



