ASTRONOMICAL PHENOMENA AND PROGRESS. 



45 



round the axis of the globe is 1,147.90 feet per second. Multiplying this amount by 86,400 seconds, i 

 The mouth of the river, it will also be seen, rotates i earn t h at f or eac h revolution of the earth, 

 in a circle of 18,246,102 feet radius, with a circum- 

 ferential velocity of 1,326.89 feet per second. Com- 

 paring these velocities, we ascertain that an increased 

 circumferential velocity of 178.99, say 179 feet per 

 second, is imparted to the water and to the sedimen- 



tary matter which it conveys during the course from 

 the centre of the basin to the mouth of the river. As 

 before stated, the annual discharge of earthy mat- 

 ter at the mouth of the river is 903,100,000 000 of 

 pounds. The centre of the basin, lat. 40 15 , being 

 2,461,320 feet nearer to the axis of rotation than the 

 mouth of the river in lat. 29 0', it will be found 

 that the increase of rotary velocity, as already stated, 

 is 179 feet per second a rate acquired by_ a fall of 

 500.6 feet. The elements are thus furnished for 

 determining with exactness the amount of retarda- 

 tion attending the change of position of the abraded 

 matter during its transfer from the basin to the 

 mouth of the river. Multiplying 903,100,000,000 

 by 500.6, we ascertain that the counteracting force 

 exceeds 452,000,000,000,000 foot-pounds annually 

 = 452 x 10 U foot-pounds in a century. The earth's 

 present vis vim being 18,875,361 x 10 M foot-pounds 

 (to be demonstrated at the proper time), it is easy 

 to calculate that the retardation, occasioned by the 

 stated reacting energy called forth by the sedimen- 

 tary matter which is carried to the ocean by the 

 Mississippi, will amount to TosSos of a second in a 

 century. In view of this small fraction of time, it 

 will be well to remind the reader that the retardation 

 of the earth's rotary velocity, inferred from the ap- 

 parent acceleration of the moon's mean motion, now 

 generally admitted by astronomers, is somewhat un- 

 der twelve seconds in a century. Insignificant as 

 this retardation appears to be, it calls for a constant 

 reacting force of 455,000,000,000 foot-pounds per sec- 

 ond, as will be shown in the course of our investiga- 

 tion. Dividing this amount by the adopted standard 

 of a horse-power, viz., 550 foot-pounds per second, it 

 will be found that a constant energy represented by 

 827,000,000 horse-power, exerted in a contrary direc- 

 tion to that of rotation, is necessary to check the 

 rotary motion to the extent mentioned, viz., rs&s = 

 Ties of a revolution in the course of a century. Ac- 

 cordingly, 720,000 years, nearly, will elapse before one 

 entire revolution shall have been lost, notwithstand- 

 ing the existence of a constantly retarding force of 

 455,000,000,000 of foot-pounds per second. We can 

 readily ascertain the aggregate of this force during 

 the long period mentioned, if we multiply the same 

 by the number of revolutions of the earth per annum, 

 and the number of seconds for each revolution ; thus, 

 455 x IQ 3 x 365.24 x 86,400 x 720 ; 000 = 103,379,867 x 

 10 17 foot-pounds. By dividing this amount of energy 

 in the earth's vis viva, 18,875,361 x 10 22 foot-pounds, we 

 ascertain that the stated enormous retardation over- 

 come in the course of 720,000 years amounts to only 

 T bw of the present rotary vis viva of our planet. Prob- 

 ably no other mode of presenting the subject could 

 give so clear an idea of the vastness of the mechanical 

 energy of a sphere 8,000 miles in diameter, whose 

 specific gravity is 2i times that of granite, revolving 

 at a rate of one revolution in 24 hours. Returning to 

 the retardation produced by the Mississippi, let us 

 bear in mind that the precipitation which causes the 

 abrasion of the solid matter and the currents by 

 which it is conveyed is the direct result of the sun's 

 radiant heat. 



In his conclusion upon thig branch of the 

 subject, Captain Ericsson shows that the ag- 

 gregate of solid matter transported from its 

 original position by the river-systems of both 

 hemispheres, and carried toward the equator 

 consequently removed to a greater distance 

 from the axis of rotation exerts a retarding 

 influence of 39,894,658 foot-pounds per second. 



we 

 a 



retarding energy, represented by 3,446,898,- 

 451,200 foot-pounds, has to be overcome. 

 From these facts and arguments, leaving out of 

 the present view the tendency of rivers, by 

 the flow of water alone, to destroy the earth's 

 vi-s viva by friction, the author claims to have 

 demonstrated that constancy of rotation of the 

 earth is incompatible with solar influence. 



The Solar Protuberances. For a period of 

 more than a year, Prof. Respighi, of Rome, 

 has made regular spectroscopic observations 

 of the border and protuberances of the sun, 

 which have been studied to advantage at 

 times other than those in which the orb is 

 eclipsed. A translation of a paper by Prof. 

 Respighi, giving the fruits of his labors, ap- 

 pears in the American Journal of Science. The 

 investigator found that protuberances having 

 the appearance of gaseous masses issuing from 

 the sun's surface are so marked and constant, 

 that it is necessary to conclude that they are 

 really produced by gaseous eruptions from the 

 sun, taking place with more or less energy, 

 and on a varying scale of grandeur. The di- 

 mensions of the protuberances differ greatly. 

 Among 4,000 of them watched by the profess- 

 or, there were more than TOO not less than 1' 

 high (or about 24,000 miles), and some were 

 not less than 6', or 144,000 miles high. The 

 development of the protuberances is ordinarily 

 announced by bright points, or patches, stand- 

 ing out upon the chromosphere, from which 

 subsequently burst forth jets more or less sub- 

 tile, which rise sometimes slowly, sometimes 

 rapidly, to considerable elevations, and then 

 fall back in parabolic forms upon the sun, or 

 diffuse themselves in masses often subject to 

 rapid changes. The author has on several 

 occasions witnessed the development, in the 

 neighborhood of spots, of enormous protuber- 

 ances, produced by the eruption of groups of 

 very slender and very brilliant jets, which in a 

 short time spread into great cloudy masses, 

 either settling down upon the surface of the 

 sun or gradually vanishing at a great height 

 above it. Outside the zone of spots, up to 

 about 70 in latitude of the sun, the protuber- 

 ances commonly remain visible for many days, 

 so that it is possible to follow by them the 

 rotation of the sun. In regard to the distribu- 

 tion of protuberances upon the solar surface, 

 he observes that in the circumpolar regions, 

 within a distance of 20 from the poles, they 

 are either not found, or occur exceptionally ; 

 and that the Northern Hemisphere is more 

 characterized by great protuberances and gi- 

 gantic eruptions than the Southern. The 

 following are some of the more valuable re- 

 sults deduced from a great number of obser- 

 vations made upon the border of the sun's 

 disk in the region of the spots : 



In the neighborhood of the spots the chromosphere 

 is rather low, quite regular, and intensely bright. 

 Upon the exact locality of a spot, or rather over its 



