212 



KNOWLEDGE. 



[September 1, 1899. 



the potential of the earth is conventionally assumed to be 

 zero. Why not then bring this to the recollection of the 

 beginner by the use of the complete expression, thus : 

 " The potential of the body is positive with reference to 

 the earth, because, on joining the body to earth, the 

 current would flow from it to earth." We are really com- 

 pelled to this convention with reference to the earth's 

 potential, and in most cases it is useful, yet here, unless 

 carefully applied, confusion will all too often be the result. 



The importance of the algebraic sign must under no 

 circumstances be neglected. A suggestion which I threw 

 out some years ago makes this evident ; assume that we 

 wish to measure the resistance of a small part of a circuit, 

 from A to B. We may use a Wheatstone's bridge, or an 

 ammeter and voltmeter. Arrived at the result in ohms, 

 how do we know whether we have been measuring the 

 small portion from A to B, or the remainder of the circuit, 

 which (to preserve our idea of direction) we call B A '? 

 Had we wished to measure this latter quantity which we 

 are supposing much greater than A B's resistance, we 

 might have connected up in precisely the same way. 

 Obviously the answer is, consider the signs of the potential 

 difference introduced. This suggestion, calculated to appal 

 the majority of students who have not long been acquainted 

 with the bridge and its use, may be developed. How can 

 one tell that the result is not the resistance in parallel 

 of the two parts of the circuit, modified by the existence 

 of P D's in that circuit, before the bridge was connected ? 

 And so on, till it may be made a positive nightmare tend- 

 ing to negative all hope of rest till it be cleared up. 



It has been urged that " Keason is the life of the law," 

 and that " Nothing is law that is not reason," yet nearly 

 aU unreasonable practices which are widespread amongst 

 electricians in their work are the direct outcome of 

 attempts at legislation concerning matters electrical. 

 While it would serve no useful end to draw attention to 

 specific instances in the past of sheer reasoning power 

 having been brought to bear on some electrical difficulty, 

 yet it cannot be denied that a great amount of thought 

 and subtle reasoning have been reqviired not merely for the 

 perfection of apparatus whose results should be as nearly 

 as possible true mathematically, but also upon systems of 

 electrical generation and distribution which in themselves 

 have formed the life-studies of many vigorous intellects. 

 It is, by the way, more than unfortunate that we should 

 retain as a common expression " generation of electricity," 

 and that we should constantly speak of generators. 

 There is a growing tendency in this direction ; in a recent 

 issue of the Poll Mall Gazette, a contributor, under the 

 heading " Science Notes," gravely asserts that Joule 

 invented the conservation of energy. But to continue, 

 while all this mental energy, of an order distinctly above 

 the average, has been actually necessary to bring appa- 

 ratus to its present condition, it must not be forgotten 

 that much of the apparatus in question is used daily in a 

 far more intelligent manner than formerly. ' To the lay 

 mind one of the most striking instances of the results 

 achieved by electrical reasoning is the fact that should a 

 fault occur on a telegraph line it can be "found' or 

 located from one end of the line, although it may be 

 hundreds of miles away from the individual making the 

 test. And not only can the actual position be fixed, but 

 a good description of the fault can be given by an intelli- 

 gent operator, and, while remaining perhaps a hundred 

 miles away from the scene of the trouble, he will be able 

 to state, with certainty, that there is a " dead earth," a 

 " partial earth," or a leak, or a break, as the case may be. 

 This must be regarded as a distinct advance, due exclu- 

 sively to a development in electrical reasoning, because. 



not more than a few years since, the only known method 

 of finding faults was a search along the line, and the 

 present condition of things must not be referred to im- 

 proved apparatus, because ten years back, or even twenty, 

 instruments were common which would have enabled the 

 operator to adopt the systems now in use ; only, these 

 systems had not yet been thought of. 



We have a common saying to the effect that " facts are 

 stubborn things," and scientists who have the courage of 

 their own opinions should be stubborn. Hence, scientific 

 fact has two claims, which may be spoken of as well 

 founded and to be stubbornly incontrovertible. It seems 

 childish to Insist that a fact is incontrovertible, but un- 

 happily the necessity exists. So long as a single exponent 

 of the somewhat exclusive science of perpetual motion 

 remains aUve, or while the inventor of a primary battery 

 continues to aim at the sale of the said battery to the 

 unfortunate public, for no better reason than that it will 

 cause the filament of a glow-lamp to become incandescent, 

 it is actually the duty of everyone who has made a 

 speciality of scientific study to insist that fact cannot be 

 contradicted, with any hope of success. If upon every 

 housetop in London one were stationed, for eight hours a 

 day, to yell "ex nihilo nihil jit," it is yet conceivable 

 that were those words expressed in every language ever 

 heard of, there would remain some who would never hear, 

 and some who would never heed, and some who would 

 contradict. 



If we wish to establish the claim of any style of thought, 

 or school of teaching, to be considered scientific, there is 

 one rigorous test which we can apply ; ask ourselves, 

 Does such thought and such teaching lead to, and 

 ultimately enunciate, facts which reasoning individuals 

 must admit to be universally true ? And, do these facts 

 conform with what reasoning beings have already admitted 

 the truth of? To such questioning, electricians can 

 answer boldly, " We are governed in our investigations by 

 laws which it would be actually futile to dispute ; and 

 under the guidance of these laws we have been able to 

 contribute largely to the spread of knowledge throughout 

 the civilized world. In our turn, permit us to ask what 

 you would have us do to establish the claim of our study 

 to be considered exact and scientific ? Let us also request 

 that the deliberate untruths which are told about us and 

 our work be rigorously suppressed. To ignorance gentle 

 treatment may well be applied, but let those who profess 

 to have attained to an exalted standard of wisdom and 

 popularity (?) keep silent, unless they are prepared to strive 

 honestly for the spreading of truth. 



But the MUlenium is not yet. When Carlyle was 

 impudent enough to say "Mostly fools, ' someone whispered 

 " Tu ijuo'iue,'' or, if not, someone neglected a distinct 

 duty, and it might have been better to shout. Reverting 

 to those stubborn things which in this connection one is 

 called upon to produce. The telegraph has an existence, 

 so that we get news within a day that would otherwise 

 have taken weeks or months to reach us. We can 

 travel distances in hours which would otherwise take days 

 or weeks. Suppose all the telegraph lines and cables 

 were cut to-morrow. The idea seems appalling, for with 

 the cutting of these lines at first stagnation almost every- 

 where would result, yet, electricians would be particularly 

 lively, and in something like an hour the majority of the 

 lines would be at work again ! If, however, with the 

 cutting of the lines the electricians aU died '' Well, the 

 world would no doubt stand still for a day or two. And 

 the infant has accomplished all this, just as it would bring 

 into existence a new race of electricians at almost 

 lightning-like rapidity. Further, as the child must be 



