92 



SCIENTIFIC NEWS. 



[July 27, 18 



the water ; seals in the same way would suffer greatly 

 from their own evolutions, and from those of their com- 

 rades. And any one who wishes to test for himself the 

 qualities of water as a conductor of vibration can do so by 

 submerging himself two or three feet, and allowing a 

 companion to strike with a stick or an oar the surface 

 immediately above him. The experiment is one which 

 he will not find it necessary to repeat. 



Whether fish can appreciate sound, as we understand 

 the word, is another question altogether, and one which 

 can be almost certainly answered in the negative. For 

 sound, in ourordinary acceptation of the term, is an atmos- 

 pheric phenomenon only, and cannot be transmitted from the 

 lighter medium of air to the denser medium of water. 

 Let the sceptical reader again dive a foot or two beneath 

 the surface of a pond, a stream, or the sea, and he will 

 find that sounds in theair above are perfectly inaudible. A 

 companion may shout or sing, or even fire a gun, and he 

 will hear nothing whatever so long as the water itself be 

 not disturbed. How, then, can we hold that fish hear 

 atmospheric sounds, seeing, moreover, that they possess 

 no external ears whatever, and that even the internal 

 auditory apparatus is so very far inferior to our own ? 

 Vibration, even of the water itself, must necessarily reach 

 them with greatly diminished intensity : and how is it 

 possible for them to succeed in hearing sounds which to 

 animals with senses far more highly organised are, and 

 must be, perfectly inaudible ? 



But how, it may be asked, are we to account for the many 

 reports of fishes recognising the sound of a bell, the 

 blast of a bugle, or the shrill call of a whistle, and hasten- 

 ing to the accustomed feeding-places in anticipation of 

 food to follow ? Stories more than one of such a 

 character have from time to time been given to the world, 

 and backed, in some cases, by quite unimpeachable 

 authority. How is evidence such as this to be set 

 aside ? 



Again the explanation is obvious enough. In one at 

 least of the instances referred to, and in that which is 

 best authenticated, the custodian of the fish was invaria- 

 bly accustomed to drive to the reservoirs in a tolerably 

 heavy cart ; and it is evident enough that the sound 

 which brought the fish to the feeding places was not 

 the stroke of the bell by which they were apparently 

 summoned, but the vibration caused by the wheels, which 

 was conveyed through the earth to the water. Sound 

 cannot be communicated from the lighter medium to the 

 denser, but from the denser to the lighter it can. And 

 the rumbling of a heavy cart would certainly be quite 

 audible to fish in a neighbouring pond or stream. Even 

 a heavy footstep near the bank will frighten the fish 

 lying beneath it, as many an angler has discovered to 

 his cost ; he who wishes to capture them must tread 

 lightly, in addition to keeping himself concealed. The 

 vibrations of a heavy bell, again, might possibly be 

 transmitted to the earth through the body of the ringer, 

 and from the earth to the water, and so to the fish. And 

 in none of the cases referred to does any precaution seem 

 to have been taken to prevent the fish from discovering 

 the presence of their keeper by other means than that of 

 atmospheric sound. Even an approaching footstep, to fish 

 born and bred in captivity, would be sufficient to 

 attract their attention : and as by long association they 

 would connect such a footstep, coming at regular inter- 

 vals, with the supply of food, it is hardly to be wondered 

 at if, on hearing it, they should manifest the eagerness 

 and excitement described. But we cannot hold that they 



hear either the whistle or the bugle, or even the footstep 

 intheordinary manner. Noimpression whatever would be 

 conveyed to their auditory organs by the former; the 

 latter would communicate vibration to the soil — which 

 is an excellent conductor of sound — and the earth in turn 

 would pass it onto the water. And so it would reach 

 the fish. 



But the appreciation of vibration conveyed in such a 

 manner, and reaching the brain without passing through 

 external auditory organs en route, is not hearing in the 

 strict sense of the term ; it is merely the shock arising 

 from a veritable blow, differing only in degree from that 

 which stuns the beaver as he swims along below the ice. 

 And thus fishes, in the ordinary interpretation of the 

 term, do not hear. Such auditory apparatus as they 

 possess, however, enables them to appreciate with 

 greater nicety vibrations which would probably be in 

 some degree appreciable had they no such apparatus at 

 all ; they can detect sounds in the water without difficulty, 

 and sounds in the earth, if not too far from land, with 

 tolerable ease. But sounds in the air, it is not too much 

 to say, they cannot hear at all, unless in some way 

 associated with, or implying, a corresponding concussion 

 of the water. 



A BIG THING IN GUNS. 



FOR two or three years past the subject of heavy 

 ordnance has engaged the attention of public men, 

 and the question whether the old style of built up 

 cannon could be superseded by others solidly cast has 

 been discussed in all its bearings. At last the matter got 

 into Congress, and, in March, 1887, twenty thousand 

 dollars were set aside for the purchase of solid steel 

 guns, provided that they could be made. 



Bids were asked from the different steel men in the 

 country for the production of a cast steel gun made by 

 either the crucible, open hearth, or Bessemer processes. 

 It was expected that there would be a very general 

 response to this invitation. On the contrary, only two 

 bids were received — one from an open hearth concern in 

 Eastern Pennsylvania, and the other from the Pittsburg 

 Steel Casting Company. 



The contract made by the manufacturers with the 

 Government called for the delivery of the gun in Wash- 

 ington ready for rifling on or before the 1st of April. Then 

 the Government allows itself seven months more before 

 expressing its opinion as to the merits of the gun. 

 Three of those m6nths can be SDent in finishing the 

 gun, and the other four in testing it at Annapolis. 



Appreciating to the full the importance of the work he 

 had undertaken, Superintendent Hainsworth's prelimi- 

 nary steps were characterised by the utmost caution. 

 There must be no mistake about the quality of steel 

 used, and its component parts must be judged with 

 undoubted accuracy. A long familiarity with the metal 

 enabled him to manufacture it with just the particular 

 qualities he required for his work. Before doing this, 

 however, the mould for the gun must be prepared. A 

 pit, twenty-five feet deep, was dug in the moulding shop 

 within easy reach of the great converter, and in this was 

 made the mould. A special sand w r as used, and soon 

 the exact shape of the exterior of the gun, muzzle down> 

 could be seen in the pit. 



By January everything was ready for the cast. The 

 mould was carefully inspected for the last time, and 

 sixty men lent their assistance to the process of pouring 



