The year 188 - was in many ways noteworthy to astronomers.<br><br>Not to make mention of Schiaparelli's indefatigable researches on the surface geography and physical conditions of the earth's sister-planet Mars, which resulted in the publication of those fine charts destined to immortalise the Italian observers name - not to speak of the learned labours of Secchi, and the ponderous volumes of printed matter which Monsieur Flammarion conferred as a heritage on our volatile next-door neighbours - not to dwell on the invaluable boon conferred on the noble science by the works of Sir Robert Ball on the sun, by the discoveries of Palisa among the minor planets, or by Struve's sage calculations concerning the nature of Saturn's mysterious rings - setting all these valuable offerings at the shrine of Urania aside for a moment, there was one topic which far outweighed the rest, one all absorbing question which deeply agitated the minds of learned and unlearned, of credulous amateurs and sceptical professors.