200 The Newly -Discovered Force. [April, 
hypothesis of rapidly reversed electricity, but they must be 
met and fully considered by those who are inclined to favour 
it. It is the more important to insist on these difficulties, 
because a number of observers who have repeated some of 
these experiments, and admit the phenomena or some of 
them, are taking instant refuge in this theory as though 
that solved the whole mystery.* 
Both theories, that of a radiant force and that of 
rapidly reversed electricity, are radically new suggestions, 
and neither of them can be, or will be, or ought to be 
accepted, except under the pressure of long-accumulating 
evidence. 
Meanwhile it should be borne constantly in mind as a 
principle of evidence that for those who admit these phe- 
nomena, and who assert that they indicate some known 
phase of electricity or magnetism, the burden of proof in 
that issue rests to make good the claim by positive proofs. 
Until such proofs are obtained the scientific mind can main- 
tain a position of neutrality, or can consider the relative 
value of the two theories here suggested. Either course 
would be consistent with the scientific spirit. The theory 
of rapidly reversed electricity apparently accounts for but a 
part of the phenomena, but it has this advantage over the 
radiant theory — that there is less presumption against it. 
If we could suppose a phase of statical electricity of low 
tension and considerable quantity, which, for some reason, 
* Prof. Houston, of Philadelphia, among others, has repeated some of these 
physical experiments, and has adopted in full, after but a partial study of the 
subjedt, the hypothesis of rapidly reversed eledlricity as suggested in my letter 
to the “ Tribune ” of December gth, and further claims priority of discovery, 
because he observed the spark of this when experimenting with a Ruhmkorff 
coil four years ago. To this claim, if it be seriously entertained, the obvious 
reply is that thousands of persons, probably, had seen this spark before it was 
discovered by Mr. Edison : it had been seen by Prof. Nipher, who supposed, 
and still supposes, it is the spark of the extra current ; it has been seen by my 
friend, Prof. J. E. Smith, who assumed, as he tells me, without examination, 
that it was indudtive electricity breaking through bad insulation ; it had been 
seen, as has been stated, by Mr. Edison many times before he thought it 
worthy of study ; it was undoubtedly seen by Prof. Houston, who, like so 
many others, failed to even suspedt its meaning, and thus missed an important 
discovery. The honour of a scientific discovery belongs not to him who first 
sees a thing, but to him who first sees it with expert eyes ; not to him, even, 
who drops an original suggestion, but to him who first makes that suggestion 
fruitful of results. If to see with the eyes a phenomenon is to discover the 
law of which that phenomenon is a part, then every school-boy who before 
the time of Newton ever saw an apple fall was a discoverer of the law of 
gravitation. Prof. Houston’s account of his repetition of some of these 
experiments was published in the “Journal of the Franklin Institute ” for 
January, 1876; and the article in which he incidentally mentions sparks that 
he now rightly recognises as the spark of this force was published in the same 
Journal, June, 1871. 
