HYPOTHESES. 357 



copied all that I could see, it is nothing strange that I should guess those 

 which I can not see, would be absurd, without supposing such a ground for 

 guessing."* If any one, from examining the greater pai-t of a long inscrip- 

 tion, can interpret the characters so that the inscription gives a rational 

 meaning in a known language, there is a strong presumption that his inter- 

 pretation is correct; but I do not think the presumption much increased 

 by his being able to guess the few remaining letters without seeing them ; 

 for we should naturally expect (when the nature of the case excludes 

 chance) that even an erroneous interpi'etation which accorded with all the 

 visible parts of the inscription would accord also with the small remain- 

 der ; as would be the case, for example, if the inscription had been design- 

 edly so contrived as to admit of a double sense. I assume that the uncov- 

 ered characters afford an amount of coincidence too great to be merely 

 casual; otherwise the illustration is not a fair one. No one supposes 

 the agreement of the phenomena of light with the theory of undulations 

 to be mei'ely fortuitous. It must arise from the actual identity of some 

 of the laws of undulations with some of those of light; and if there be 

 that identity, it is reasonable to suppose that its consequences would not 

 end with the phenomena which first suggested the identification, nor be 

 even confined to such phenomena as were known at the time. But it does 

 not follow, because some of the laws agree with those of undulations, that 

 there are any actual undulations ; no more than it followed because some 

 (though not so many) of the same laws agreed with those of the projection 

 of particles, that there was actual emission of particles. Even the undula- 

 tory hypothesis does not account for all the phenomena of light. The nat- 

 ural colors of objects, the compound nature of the solar ray, the absorption 

 of light, and its chemical and vital action, the hypothesis leaves as myste- 

 rious as it found them ; and some of these facts are, at least apparently, 

 more reconcilable with the emission theory than with that of Young and 

 Fresnel. Who knows but that some third hypothesis, including all these 

 phenomena, may in time leave the undulatory theory as far behind as that 

 has left the theory of Newton and his successors ? 



To the statement, that the condition of accounting for all the known 

 phenomena is often fulfilled equally well by two conflicting hypotheses. 

 Dr. Whewell makes answer that he knows "of no such case in the history 

 of science, where the phenomena are at all numerous and complicated."f 

 Such an affirmation, by a writer of Dr. Whewell's minute acquaintance with 

 the history of science, would carry great authority, if he had not, a few 

 pages before, taken pains to refute it,J by maintaining that even the ex- 

 ploded scientific hypotheses might always, or almost always, have been so 

 modified as to make them correct representations of the phenomena. The 

 hypothesis of vortices, he tells us, was, by successive modifications, brought 

 to coincide in its results with the Newtonian theory and with the facts. 

 The vortices did not, indeed, explain all the phenomena which the Newto- 

 nian theory was ultimately found to account for, such as the precession of 

 the equinoxes; but this phenomenon was not, at the time, in the contem- 

 plation of either party, as one of the facts to be accounted for. All the 

 facts which they did contemplate, we may believe on Dr. Whewell's au- 

 thority to have accorded as accurately with the Cartesian hypothesis, in its 

 finally improved state, as with Newton's. 

 .^ But it is not, I conceive, a valid reason for accepting any given hypothe- 



* Phil, of Discovery, p. 274. f P. 271. % P. 251 and the whole of Appendix G. 



