DEVICES FOR USE IN FISH HATCHERIES AND AQUARIA. 



'O33 



and the siphon therefore is not feasible, the handle is removed from the cleaning 

 apparatus and a pump attached. A small suction pump, such as used in gardens, 

 is very suitable. If for any cause convenient, the apparatus may be left in 

 the pond, for with the valve closed the suction can not act. 



OXYGENATION AND VACUUM-PRODUCING APPARATUS. 



This apparatus is in effect a section which may be introduced into a supply 

 pipe, and consists of an exhaust chamber and an air-supply tube, with the essen- 

 tial feature of a movable jet. The differences of 

 water pressure and sizes of supply pipes render a 

 stationary jet ineffective or even useless at times. 



The model here represented has a jet of 5 to 6 

 millimeters diameter, adjustable by means of a screw r^j^rp 

 on the outside, and sends air into the water to a 

 depth of about 4 meters, from an opening of 20 mil- 

 limeters. It may be mounted with openings varying 

 from 20 to 26 millimeters. The lower part of the 

 apparatus is provided with a movable tube having 

 a conical entrance, to divide the water better and 

 make the vacuum stronger. 



The pressure of the water of the Vanne is dimin- 

 ished in the sluices of the Trocadero Aquarium by 

 the many separate outflows, and to provide the de- 

 sired currents, 13 of these oxygenators have been in- 

 stalled. The fashes playing in the numerous silvery 

 bubbles which rise from the bottom arouse much ad- 

 miration from the public, and it will be readily be- 

 lieved that the fish are clean and never sluggish. 

 Small or large, they thrive with this kind of aera- 

 tion, which brings them artificial currents of water 

 which they did not find in these same ponds before. 

 These currents, moreover, do not allow the food given 

 to fall to the bottom when it is sprinkled in. The 

 young fish, some 5 or 6 weeks old, may be seen to 

 catch in passing the small particles of food which the 

 water brings them . The ponds are from 2 to 3 meters 

 deep, from 7 to 8 meters long, and from 2 to 3 meters 

 wide. These oxygenators render great service; it is a hygienic method which 

 ought to be used wherever possible. 



This apparatus may be used without disarrangement for the purpose of 

 producing a vacuum in boxes specially prepared for the preservation of food 

 for fishes and even for the shipment of fishes destined for market. It may be 



B. B. F. lf)oS— Pt 2—23 



5. — Oxygenator and vacuum 

 producer. 



