Chase.] 5o4: [Nov. 4, 



13. Chemical Action. — The evidences of incessant dissociation and re-as- 

 sociation in tlie solar photosphere, are so conclusive, that chemical action 

 may be very properly regarded as an important source of specific solar 

 magnetism. 



y. Light. — The numerical equivalences between various forms of lumi- 

 nous, gravitating, and electro-magnetic action, are so striking as to justify 

 Maxwell in the assertion that "the properties of the electro-magnetic 

 medium are identical with those of the luminiferous medium."* 



d- Seat. — Edlund has shown that many of the phenomena of heat and 

 electricity may be explained by the hypothesis of two forms of motion in 

 the same elastic sethereal medium. 



£. notation. — Arago, Babbage, Herschel, Barlow, Christie, Chase, and 

 Perry and Ayrton, have shown that simple rotation produces magnetical 

 disturbances which are governed by fixed laws. 



^. Gravitation. — In addition to the relation which I have shown to exist 

 between solar rotation and luminous velocity, it is evident that electricity 

 must be modified by pressure and by such changes in the relative distances 

 of electrified particles as are produced by disturbances of gravitating equi- 

 librium. 



rj. Currents. — A comparison of oceanic currents with the cotidal lines, 

 the lines of isabnormal temperature and the magnetic lines of equal 

 declination, shows such points of resemblance as to make it probable that 

 they are all due to the action of the same forces upon diflerent media, or 

 under different circumstances. Challis has found that if all the ordinary 

 central forces are due to transformed sethereal vibrations, " the actions of 

 such forces on atoms are in every instance attributable to mthereal currents, 

 whether the atoms be immediately acted upon by steady motions of the 

 sether or by sethereal vibrations." f 



130. Comparison of Solar Daily Magnetic and Meteorological Means. 



The solar-daily maximum of vertical force at St. Helena is coincident 

 with the daily barometric minimum, as well as with the minimum of gase- 

 ous pressure and of mean pressure of the wind. The daily minimum of 

 vertical force (20 h) is approximately coincident with the daily maximum 

 of the barometer (22 h), of gaseous pressure (21 h), and of wind pressure 

 (22-23 h). The most rapid increase of vertical force is between 22 h and 

 3 h, when the barometer is falling and the gaseous pressure diminishing ; 

 the most rapid diminution is between 7 h and 10 h, when the barometer is 

 rising and the gaseous pressure increasing. The range of total force be- 

 tween noon and midnight (.00095 + .00043 = .00138), is of the same 

 order of magnitude as the daily range of solar disturbances of weight or 



/ m 

 pressure ( -^ = .000615, which is added at midnight and subtracted at 



* Eleciriaity and Magnetism, ii, 383, sqq. 



t Phil. Mag., Sept. 1872 ; Sept. 1876 ; J une, 1878. 



