If a popular science article serves none of these three purposes, it must inevitably be nothing but the description of a “marvel.” In competent hands this may be agreeable enough; the appetite for marvels is vigorous and universal, and its indulgence cannot be condemned as a vice. To look at a marvel for the pleasure of gaping is not, however, a very intelligent occupation, and, to judge from the number and kind of phenomena unhesitatingly ascribed to “the electricity in the air,” merely increases credulity. Regarded as a marvel, wireless telegraphy is, of course, merely a miracle, a fact extensively exploited by spiritualists. The human tendency to seize on the merely marvellous should, in fact, be carefully allowed for by the writer of popular science articles; he should, if anything, be even more reserved and pedantically precise than when addressing a scientific audience; an incautiously flamboyant remark is very likely to be seized upon to support some preposterous philosophy or religion. Usually, however, the popular science writer yields to the temptation, to _épater_ his audience, to make himself more readable, as readability is now understood, and so he may, while speaking the truth, have all the effect of telling a lie. Thus the division between the genuine and the quack science article is not, in practice, clearly defined. The difference between the writers is definite enough; but it is writer and public together which make the popular science article. Lack of education is just as great a hindrance to perception as is lack of sensitiveness. The poet may be subtly and completely misunderstood because his audience lacks sensitiveness, and, to compare small things with great, the conscientious retailer of scientific information may be in a like case for a different reason. So that if it is true that the best type of poetry is that written by the poet “for himself,” it is perhaps true that the best type of popular science article is written for a similar reason--because the writer is genuinely interested in working out certain speculations or treating certain facts in a certain way. Some of the very best popular articles--those by Helmholtz, for example--are of this kind, and have achieved a relative immortality, although, like the poetry which is read chiefly by poets, they are probably read chiefly by scientific men. PATIENT PLODDERS