I034 BULLETIN OF THE BUREAU OF FISHERIES. 



of various sizes and may be placed at the base of a reservoir or even in a recepta- 

 cle in an automobile for the transportation of fishes alive. In this case the 

 motor will turn a small pump in the apparatus and this even during stops, with 

 the exception of cases when the motor itself does not work. 



I have a small oxygenator at the extremity of a small hand pump, to serve 

 me for long transportations. This is more practical than an air pump, the 

 globules from which are too large and must be divided. By means of its water 

 jet, which carries the air along, the oxygenator divides its globules, and these 

 rising less rapidly to the surface, aerate the water much better than the large 

 globules. 



The discharge pipe of the oxygenator must be sufhciently large to contain 

 at the same time the air and the water which must pass through it together. 

 Thus if it should be found necessary, as for instance, if the ponds need to be 

 cleaned by flushing, it is possible to attach at the connection of the air pipe a 

 joint identical with the water pipe and use this double water supply in spite of 

 the presence of the oxygenator which might seem to intercept it. Or the spigot 

 of the air pipe may be closed and the flow of water is then normal. 



Some three years ago I placed with a manufacturer a design for an oxy- 

 genator, but feeling some distrust withheld the feature of the sliding jet, though 

 I mentioned it. It was well that I did withhold it, for not only did I lose 

 my apparatus but the idea was stolen, though I retained the secret of the true 

 mode of operation. The sliding jet is indispensable to success. In a locality in 

 the north of France a system of oxygenators installed at great expense afterwards 

 necessitated the modification of a great part of the plumbing and changes in the 

 size of jets, all of which is obviated by the sliding jet. 



SCRAPER FOR PREPARING FISH FOOD. 



Fish culturists know that it is not a very agreeable or easy task to extract 

 the pulp from the spleen of horses or beeves, and that it is, moreover, a very long 

 and fatiguing operation if a knife, spoon, or any such instrument is used. For 

 my part, having some 15 kilograms and sometimes more of spleen to scrape, I 

 endeavored to find a readier means. 



My device somewhat resembles a block plane in shape, with 5 blades pro- 

 truding their full depth. I had to seek a long time for blades of requisite flexi- 

 bility, shape, and size, and to fit them in proper place and at proper inclination. 

 It will be seen that these blades have not all the same shape. This is because 

 each has its definite place of contact, none scraping directly on the spot which 

 the preceding blade has scraped. Otherwise the pulp would be immediately 

 torn at the first stroke of the scraper. I have likewise overcome the other 

 difficulties encountered at the beginning of the attempt at this device. 



The following is the mode of proceeding : 



