1 87 1.] The Fuel of the Sun. 453 



activity is not exactly intermediate between the poles and 

 the equator, but lies nearer to the solar equator. 



Examined with the polariscope, these radiant streams 

 should display a mixture of reflected light and self-lumi- 

 nosity. Examined with the spectroscope, a faint continuous 

 spectrum due to such luminosity of solid particles should 

 be exhibited, with possibly a few doubtful lines due to the 

 small amount of vapour which, in their glowing condition, 

 they might still give off. Besides this, there should appear 

 the spectroscope indications due to violent electrical dis- 

 charges, which must occur as a necessary concomitant of 

 the furious ejections of aqueous vapour and solid particles. 

 All these metallic hailstones must be highly charged, like 

 the particles of vesicular vapour ejected from the hydro- 

 electric machine, or the vapours and projectiles of a terres- 

 trial volcanic eruption. 



I need scarcely add that this exactly describes the actually- 

 observed results of the recent observations on the corona, 

 and that all the phenomena of this great solar mystery are 

 but necessary and predicable results of the constitution I 

 ascribe to the sun. 



There is a method of manufacturing hypotheses which 

 has become rather prevalent of late, especially among 

 mathematicians, who take observed phenomena, and then 

 arbitrarily and purely from the raw material of their own 

 imagination construct explanatory atoms, media, and actions, 

 which are shaved and pared, scraped and patched, lengthened 

 and shortened, thickened and narrowed, till they are made 

 to fit the phenomena with mathematical accuracy. These 

 laborious creations are then put forth as philosophical 

 truths, and, afterwards, the accuracy of their fitting to the 

 phenomena is quoted as evidence of the positive reality of 

 the ethers, atoms, undulations, gyrations, collisions, or 

 whatever else the mathematician may have thus skilfully 

 created and fitted. It appears to me that such fitness only 

 proves the ingenuity of the fitter, — the skill of the mathe- 

 matician, — and that all such hypotheses belong to the 

 poetry of science ; they should be distinctly labelled as 

 products of mathematical imagination, and nowise be con- 

 founded with objective natural truths. Such products of 

 the imagination of the expert may assist the imagination of 

 the student in comprehending some phenomena, just as 

 ''Jack Frost" and "Billy Wind" may represent certain 

 natural forces to babies ; but if Jack Frost, Billy Wind, 

 electric and magnetic fluids, ultimate atoms, interatomic 

 ethers, nervous fluids, &c, are allowed to invade the 



