574 



THE POPULAR SCIENCE MONTHLY, 



spears, or hook and line, serve the purpose ; 

 but, in order to supply the now enormous- 

 ly increased demand, drift-nets are used. 

 These are thi-ee quarters of a mile in length, 

 twenty feet in depth, and have a mesh suf- 

 ficient to allow the head of a fish to enter 

 as far as the gills. The fishing-season lasts 

 from April to July, and during this time the 

 work is prosecuted with vigor. Everything 

 required in the business is manufactured on 

 the premises. Foreigners are employed to 

 do the work ; Italians capture the fish and 

 Chinamen prepare it for consumption. The 

 fish, placed in racks in quantities, at the en- 

 trance of the cannery, are readily accessible. 

 A flexible water-pipe directs its searching 

 flow of water on to the salmon to cleanse 

 them, after which they are sorted and placed 

 within reach of the first opei'ator. He takes 

 oif head, fins, and tail ; making an incision 

 into the back, the intestinal matter is re- 

 moved, and the fish thrown into a tub half 

 filled with water. The second operator 

 scrapes and washes it, and passes it on 

 to man number three for inspection. The 

 fourth person ranges the bodies in a trough, 

 where by means of blades driven by a crank 

 they are cut to pieces. These are now neatly 

 packed in cans, a spoonful of salt is put into 

 each one, the lid is soldered down, and the 

 cans are then ready for the cooking-house. 

 Here immersed in a huge steamer they cook 

 an hour. Removed from the steam-bath, 

 they have each a small hole bored in them, 

 to admit of their quickly cooling. The tins 

 are next placed in boiling salt water, where 

 they remain two hours. They are again 

 examined, now to see that the ends have 

 assumed a concave shape. Such tins as 

 have not taken this shape are condemned, 

 while all others are passed forward to be 

 varnished and labeled. Before being sent 

 to market they are again examined, and im- 

 perfect cans are rejected. 



Voice in Fishes.— Mr. S. E. Pool, in a 

 late number of " Nature," gives an account 

 of an interesting observation of his own in 

 support of the claim that fishes possess a 

 faculty of voice. He states that, when en- 

 gaged in a survey of the " Disang River 

 in eastern Assam " some six years ago, he 

 had occasion to sound the depth of a pool. 

 When seated in a small canoe and slowly 



nearing it, he suddenly became aware of the 

 presence of a number of fish called " mah- 

 sir." They were evidently attracted by the 

 canoe, and Mr. Pool surmised that they 

 might possibly think it a huge dead fish. 

 While watching their movements, he be- 

 came " aware of a peculiar ' cluck ' or per- 

 cussive sound — frequently repeated, on all 

 sides, and coming from below," but near by. 

 This was soon traced to the mahsir, and one 

 of them made distinct sounds which were 

 answered by others. He further states that 

 in some parts of eastern Assam a large bi- 

 valve sings in concert with others. 



Expansion of Bodies by Electrification. 



— In a communication to the Paris Acad- 

 emy of Sciences, E. Duter describes some 

 experiments which have led him to the con- 

 clusion that bodies are increased in bulk by 

 electrification. A large thermometer-tube 

 is filled with water and coated externally 

 with tin-foil, forming a Leyden-jar or con- 

 denser, with the water for the interior con- 

 ductor, the foil for the exterior conductor, 

 and the tube for the insulator — a platinun 

 wire dipping into the water as a charging 

 rod or electrode. As soon as the jar is 

 electrified the water sinks to a lower level, 

 and so remains till the jar is discharged. 

 The inference is, that the glass is dilated 

 by electrification, and this inference is 

 strengthened by the fact that the same ef- 

 fects are produced whatever be the nature 

 of the armatures, whether tin-foil, water, 

 saline or mercury solutions. To remove all 

 doubts, M. Duter modified the apparatus by 

 placing the tube (or Leyden-jar) in a closed 

 envelope of glass, terminated also by a 

 thermometer-stem and filled equally with a 

 liquid conductor. In this arrangement the 

 liquid of the internal reservoir formed the 

 interior armature of the condenser, and the 

 liquid of the envelope formed the exterior 

 armature, the glass tube being, as before, 

 the insulator. On electrification, while the 

 inner liquid sank, the outer liquid rose to 

 an equal amount, thus proving the accuracy 

 of the inference. On discharge of the elec- 

 tricity, the original levels were restored. 

 The conclusion is, that the internal capaci- 

 ty of a Leyden-jar and its external volume 

 are increased by charging it with static elec- 

 tricity. Temperature can not cause this 



