PROFESSOR BOEELLI'S EXPERIMENTS. 45 



which unite the greatest velocity with the greatest degree of 

 strength must be reckoned the whale ; for, struck with a har- 

 poon or spear with a line attached, the leviathan of the waters 

 darts down into the deep with such velocity that if the line 

 were to entangle it would either be broken or the boat would 

 be capsized. Upon the act of striking a whale, therefore, one 

 man is stationed to give his whole attention to the line run- 

 ning off clear, while another is employed to pour water con- 

 tinually on the wood over which the line runs, to prevent ig- 

 nition by friction. The angler knows that the sheepshead 

 has this power of diving with the velocity of lightning ; so 

 have all fishes which are swift and wide compared to their 

 length. In diving or darting upward, the swim-bladder is a 

 great assistance, as it is found to be compressed while the 

 fish is at the bottom, and expanded when the fish is on the 

 surface of the water. Probably the salmon and the bluefish 

 unite the greatest amount of muscular strength to the great- 

 est power of propulsion. Other fishes of our coast, such as 

 the Spanish mackerel, bonetta, cerus, and the horse mackerel, 

 add to the muscularity of the salmon and bluefish the propul- 

 sive power of the swordfish and the dolphin. The pectorals, 

 ventrals, and anal fins assist the fish in maintaining its bal- 

 ance or level position of body. In experimenting upon the 

 use of fins, Professor Borelli, of Naples, ascertained that after 

 clipping oif the pectoral, ventral, and anal fins of fishes, all 

 their motions became unsteady, and they reeled frcm right to 

 left, and up and down, in such irregular manner as to prove 

 that they were left at the mercy of their voracious neighbors 

 of the deep. 



