SUNIER: The Laboratory for Marine Investigation. 141 



The lowest part of the suction pipes, to which the foot valve is at- 

 tached, hangs freely in the water and can be detached from the upper 

 portion with a view to possible repairs to the foot valves. 



The delivery pipes of the three pumping sets are joined up into one 

 main delivery pipe by means of a three way cock placed just above the 

 pumping sets. Both pipes and three way cock are also entirely of hard 

 phosphor bronze. 



This delivery pipe eventually discharges into a reinforced concrete 

 duct open on top but protected against evaporation and dirt by being 

 covered with fibro cement sheets cut to size (cf. top edge of Diagram). 



This duct, which is supported just under the ceiling, runs through the aqua- 

 rium chamber first of all in a longitudinal direction from East to West above 

 the small tanks and the two tables belonging to them (2 and 3, Plan No. 3). 



Thence the duct makes a bend of 90 degrees so as to cross the 

 West wall of the aquarium chamber close and parallel to it. 



After having made another bend of 90 decrees the duct runs again 

 through the aquarium chamber also in a longitudinal direction, but this 

 time from West to East, above the large tanks and their two tables, 

 (1 and 3, Plan No. 3) finally ending East of the South Eastern table. 



Immediately before this ending the duct opens out into an earthen- 

 ware pipe of 10 cm. internal diameter, which makes a watertight joint 

 with the floor of the duct (see right-hand top corner of the Diagram.) 



Owing to the fact that this pipe projects about 5 cm. through the 

 bottom of the duct it acts as an overflow, and however hard the pump 

 works, the water in the duct remains at a constant level. 



The water passing through this overflow discharges into a waste water 

 duct which, as is described below, runs along the back of the large tanks. 



in the bottom of the duct which, as recentlv referred to, is suspended 

 from the roof of the aquarium chamber and which serves as an elevated 

 reservoir, a number of ebonite cocks are fitted. 



Above each of the four small tanks, (2, Plan No. 3), and each of the 

 four tables, (3, Plan No. 3), are three cocks. Above each of the large tanks, 

 (1, Plan No. 3), are six cocks (see Diagram). 



To the lower end of each of the ebonite cocks is attached a thick 

 rubber hose of 2^2 cm. internal diameter, the bottom end of which is 

 connected to a glass water jet air pump by means of a closely fitting 

 rubber stop with a hole bored in it. 



The outlet pipe of this pump projects just beneath the water surface 

 of the tanks. 



The water which comes out of the outlet pipes of these water jet air 

 pumps is, from the nature of the plant, throughly mixed with fine air bubbles. 



1 was compelled to use these air pumps because I could not get a 

 strong enough stream of water in the tanks out of the top duct, which is 

 only 1.60 M. to 1.85 M. above the watersurface of the tanks. 



