158 



p. R. WALNE 



D 



7%-^^// ///O///// 



T 



r 



Figure 3. — Left — System for enriching the warm sea water with algal culture : A, stirrer ; B, algal 

 culture reservoir ; C, solenoid-operated pinch clip ; B, warm sea water supply ; E, hard-rubber 

 ball valve ; F, header and mixing tank. Right — Detail of distribution manifold to aquariums : 

 A, i/^-inch polythene pipe; B, coupling nut; C, %-inch polythene T-tube with screwed ends; 

 D, glass tube ; E, rubber stopper ; F, coupling nut ; G, Hoffman screw clip operating on a piece 

 of rubber tubing. 



Figure 4. — Timing device for dosing algal culture into the sea-water system : A, mercury tilt switch ; 

 B, adjustable contact arm ; C, brass cradle on a pivot ; D, synchronous motor ; E, 4 arms rotating 

 at 1 r.p.h., each in turn making mechanical contact with B. 



aquarium over a period of 15 minutes show 

 the even amount of enrichment obtained : 



Count of Phaeodactylum cells 

 per cubic millimeter at — 



minutes 43 



3 minutes 55 



7 minutes 48 



11 minutes 45 



15 minutes 50 



The enriched and heated water is dis- 

 tributed to the aquariums from a manifold 

 made up of a series of T-tubes (fig. 3). 

 The T-tubes and their interconnections are 

 domestic cold-water polythene compres- 

 sion fittings (Plastronga, Yorkshire Im- 

 perial Metals Ltd.). As the flow rate is 

 rather slow but continuous in this part of 



