SCIENCE. 



241 



changeable with them. In this view inertia is a law of 

 energy and not a property of matter. 



The following table gives a synoptical view of the 

 various forms of energy and the names they have. 

 Where there are no names an interrogation point is 

 placed to indicate the lack. To the writer it appears 

 as if each specific form of energy should have a spe- 

 cific name, but he is aware of the difficulty of finding 

 suitable names and getting them adopted. If this 

 want is felt by others then a committee of suitable 

 persons might be appointed by the American Associa- 

 tion for the Advancement of Science, who might con- 

 sider and recommend appropriate names as did the 

 British Association for Electrical Science some years 

 ago. 



TABLE OF FORMS OF ENERGY. 



i. Mechanical or Molar Motion. 



Form. Name. 



{ Rec'ilinear ? 



Rotary ? 



P my 1 J Vibratory Sound. 



2 1 Curvilinear ? 



Spiral 



[ Vortical 



2. Atomic and Molecular. 



E =e 



f Rectilinear Free path. 



I Rotatory Electricity. 



J Vibratory Heat. 



Curvilinear ? 



Spiral ? 



Vortical ? 



E 



E ='% 



E= ? 



Atomic and Molecular. 



? Specific heat. 



Latent heat. 



Specific Indue. Capac. 



4. In Ether. 

 ( Rectilinear ? 



Vibratorv \ Pulsator y Chemism. 



3 I Undulatorv Radient Energy. 



(Light. 

 Pser.do-? Heat. 



^Actinism. 

 Rotatory, ) Circularly and ) , , T • ,. 



Curvilinear,^ EllipticaLy ( -Polanzed Light. 



Spiral Magnetism. 



^ Vortical Matter. 



THE SPANISH MACKEREL AND ITS ARTIFI- 

 CIAL PROPAGATION. 



By Chas. W. Smiley. 



This fish, Cybium Maculatum, is in general appear- 

 ance very like the common mackerel. It is larger, how- 

 ever, averaging seventeen to twenty inches in length. 

 When first described it did not exist in our waters, but 

 was abundant in the Guli of Mexico and the Caribbean 

 Sea. Its first appearance was about 1850. It then began 

 to be taken as a food fish. It began to be caught in the 

 Chesapeake about 1870. About 1872 or 1873 it appeared 

 in Narragansett Bay, when three or four hundred were 

 taken at one haul of the seine, but the fish did not sub- 

 sequently reappear. 



The Chesapeake Bay has been annually visited by 

 large schools for several years, where it is known as the 

 " Bay mackerel." None were known to have been mark- 

 eted there prior to 1870, but in 1879 1,300,000 of this fish 

 were sold, and the season of 1880 is expected to yield 

 2,000,000. They were taken in pound nets and gill-nets. 



At Cherrystone, Md., there are fourteen pounds, which 

 average a catch of 500 to a day. As many as 4,000 per 

 day have been taken in a single pound on the eastern 

 shore of the Chesapeake, while 2,500 is not a rare catch 

 with one pound. The Bay fish are, however, smaller 

 and leaner than those caught further north. 



As this fish refuses the hcok its capture is limited to 

 pounds and nets. The first pound in the Bay was built 

 in 1875. Now there are 164. The first gill-net used 

 there was in 1877, while now there are 175 men fishing 

 by this means. A net 100 fathoms long will average 

 forty fish per twenty-four hours, the fish weighing from 

 one and a half to two pounds each. 



In the New York market the price per pound ranged 

 from eighteen to thirty cents during 1879 ; for May, 1880, 

 from fifteen to forty cents ; but owing to the large ship- 

 ments in June the price fell to ten to fifteen cents. On 

 special occasions the fish have been sold readily at one 

 dollar per pound. The catch of 1873 at Newport, R. I., 

 was sold at prices varying from seventy- five cents to one 

 dollar per pound. 



This fish usually appears in the Chesapeake in May, 

 when the temperature has reached 65° or 70 , and the 

 number increases until the middle of June. They remain 

 abundant until September, and diminish as the tempera- 

 ture of the water falls, until, in early October, nearly all 

 have disappeared. They come in small schools, but later 

 get scattered, and often quite isolated. Before leaving, 

 the schools seem to be somewhat reformed. 



The United States Fish Commission, under the man- 

 agement of Professor S. F. Baird, the Secretary of the 

 Smithsonian Institution, has long desired to experiment 

 upon the artificial propagation of this fish, but has been 

 deterred by the lack of knowledge of its spawning time 

 and places. These were both discovered June 1st by 

 Messrs. Earll and McDonald, Assistants of the Commis- 

 sioner. At that date the lower Chesapeake, especially 

 Mobjack Bay, was found to contain large numbers of 

 spawning mackerel. This opened the way for experiments, 

 and Professor Baird was ready to seize upon the oppor- 

 tunity. He directed Mr. Earll to make every effort to 

 hatch some fish. 



June 21 Mr. Eaill started for Crisfield, Md., on the 

 eastern shore of the Chesapeake, and during the follow- 

 ing ten days there conducted his experiments. 



He found the number of eggs produced by a single 

 fish to be from 50,000 to 500,000, according to the size of 

 the fish, the latter number having been taken from a fish 

 weighing one and three-fourths pounds. Instead of all 

 the eggs ripening at once, as is true in the case of the 

 shad, only a part are thrown at a time, and at intervals 

 of a few days, probably extending through two or three 

 months. This is analogous to the cod, which deposits 

 its eggs at intervals during five or six months. D fferent 

 individuals of mackerel were found to vary in their time 

 of spawning; some ripening a considerable time before 

 others, and the males seeming to ripen somewhat in ad- 

 vance of the females. From 40,000 to 130,000 eggs 

 were obtained at one time from a single fish. The shad, 

 however, yields only 20,000 to 30,000 as its fruits of an 

 entire season. The cod, on the other hand, are so prolific 

 that a twenty-one pound fish has yielded 2,700,000 eggs, 

 and a seventy-pound fish has yielded 9,000,000 eggs. 



When the fish had remained in the nets several days Mr. 

 Earll found that the most of the spawning females had 

 deposited all their ripe eggs. The greatest quantities 

 were secured from individuals that had remained in the 

 pound but a few hours. It is believed that when con- 

 fined the female presses against the netting in its efforts 

 to escape and produces an abnormal discharge of eggs ; 

 but it would result in the impregnation of a much larger 

 number of eggs than would chance to be fertilized in a 

 natural way. The males and females being caught side 

 by side in considerable numbers, both eggs and milt 

 would be present in the water in such quantities that 



