Every age has its problem, by solving which humanity is helped forward.

Heinrich Heine.

In previous pages allusion has been made to the distinguished character of the astronomers who have contributed to a knowledge of the surface markings of Mars. Testimony from astronomical sources has been quoted as to their keen-sightedness in this work which, as Sir Robert Ball has said, "indicates one of the utmost refinements of astronomical observation." That the reader may better understand the eminence of some of those whose names will forever be associated with the investigation of the surface features of Mars the following brief records are given.

The two astronomers most widely known in connection with the study of Mars are Professor Giovanni Schiaparelli and Professor Percival Lowell. Lowell had just graduated from Harvard, at the age of twenty-one, when Schiaparelli, at the age of forty-two, made his first great discovery of the canali of Mars. Macpherson, in his valuable history of the "Astronomers of To-day," says of Schiaparelli: "His studies of meteoric astronomy, of Mars, Venus, and Mercury, of double stars and of stellar distribution, have given him a place second to none among living students of the heavens." From the same interesting book we gather the following facts: Schiaparelli was born in Sabigliano, in Piedmont, in 1835. He attended the usual schools in his native town and then entered the University of Turin as a student of mathematics and architecture. Before he was twenty years old he decided to devote himself to the study of astronomy. At the age of twenty-four he was an assistant in the celebrated Observatory of Pulkova. When the kingdom of Italy was organized he became an assistant in the Brera Observatory, Milan. He became suddenly famous at the age of twenty-seven by the discovery of a new asteroid. In 1862 he became Director of the Observatory. Schiaparelli's first great discovery was the relationship between comets and meteoric showers. In 1872 he was accorded the gold medal of the Royal Astronomical Society for his various astronomical discoveries. Professor Simon Newcomb gives him high praise when he says: "Among the individual observers Schiaparelli may be assigned the first place in view of his long continued study of the planets under a fine Italian sky, the conscientious minuteness of his examinations, and his eminence as an investigator." Schiaparelli's researches into the relation of comets and meteors "were developed in 1873, in his remarkable work 'Le Stelle Cardenti,' which is, according to Sir Norman Lockyer, one of the greatest contributions to astronomical literature which the nineteenth century has produced." Macpherson closes his interesting memoir of Schiaparelli by saying: "His devotion to astronomy, his singularly accurate observations and his wonderful discoveries have secured for him an exalted position among the greatest astronomers of modern times." For a further appreciation of the work of Schiaparelli the reader is referred to Macpherson's "Astronomers of To-day." In this brief sketch the reader may judge of the eminent character of one who insists that the lines in Mars are a persistent feature of its surface, whatever one's interpretation of them may be.

Percival Lowell was born in Boston in 1855. He was graduated from Harvard in 1876, and prepared for his graduating thesis an essay on the Nebular Hypothesis. Lowell is a many-sided man. Early interested in mathematics, he became one of the founders of the Mathematical and Physical Society of Boston. A visit to Japan, where he lived a number of years, resulted in the writing of three interesting books: "The Soul of the Far East," 1886; "Noto," 1891; and "Occult Japan," 1894. During his residence in Japan he was chosen foreign Secretary and adviser to the Korean Special Commission, then about to visit the United States, which he accompanied. On his return to Korea he was the guest of the Korean Government, and this experience prompted him to write "A Korean Coup d' État," 1894, and his well-known volume, "Choson, the Land of the Morning Calm," 1885. On his return to America he undertook an eclipse expedition to Tripoli with Professor Todd. His early interest in astronomical subjects was now fully awakened, and the red planet, which he had observed in boyhood with a small telescope from the roof of his father's house, aroused his interest on account of the heated discussions over Schiaparelli's discoveries. With an impetuosity and enthusiasm which characterizes all his work, he set about to secure a proper region and a sufficient elevation for an observatory site. This was found in northern Arizona at an elevation of over 7,000 feet. Here, then, was established the Lowell Observatory with a twenty-four inch refractor made by Clark especially for this Observatory, the last, and, according to the maker's words, the best telescope he had ever made. Lowell insisted that the location of an observatory was a much more important factor than the size of the instrument, and says: "When this is recognized, as it eventually will be, it will become the fashion to put up observatories where they may see rather than be seen." It may be said with truth that, for the first time in the history of astronomy, an observatory has been erected and fitted for the special purpose of studying the surface features of Mars. During unfavorable oppositions Lowell has turned his attention to the other planets, notably Mercury and Venus, with the result of adding many new and interesting details concerning these bodies. Three volumes of quarto memoirs and many bulletins from the Lowell Observatory attest to his industry. He has been fortunate in securing talented assistants, and their contributions may be found in the various publications of the Observatory. The character and importance of Lowell's work may be understood by stating that the "British Nautical Almanac" is to adopt for the future the value of the position of the axis of Mars, and the tilt of the planet's equator to its ecliptic, which was furnished by Professor Lowell in compliance with a request.

Mr. Lowell is a Fellow of the American Academy of Arts and Sciences; Member of the Royal Asiatic Society of Great Britain; American Philosophical Society; SociÉtÉ Astronomique de France; American Astronomical and Astrophysical Society; Astronomische Gesellschaft; SociÉtÉ Belge d'Astronomie; Fellow of the American Geographical Society; Honorary Member Sociedad Astronomica de Mexico; and others.

In 1904 he was awarded the Janssen medal of the Astronomical Society of France for his researches on Mars.

Mr. Macpherson, in his memoir on Lowell, says that "Mr. Lowell, by his unwearied devotion to astronomy, has already gained for himself an enduring reputation."

M. Henry Perrotin and his assistant, M. Thollon, have been quoted in previous pages as having markedly confirmed the discoveries of Schiaparelli. Through the courtesy of Professor Lowell I am enabled to present the likenesses of these two astronomers. I am indebted to the exhaustive work of Miss Agnes M. Clerke, entitled the "History of Astronomy during the Nineteenth Century," for the following memoranda of some of the work accomplished by these men. Perrotin made a series of observations on Venus fully confirming Schiaparelli's inference of synchronous rotation and revolution: "A remarkable collection of drawings made by Mr. Lowell in 1896 appeared decisive in favor of the views of Schiaparelli." In other words, Venus, like the Moon, presents the same face to the Sun in its revolution about that luminary. Perrotin has made important observations on the rings of Saturn; his double-star measurements are also considered work of the highest character.

Thollon has made many spectroscopic studies, among which were delicate experiments showing the lateral displacement of lines in the solar spectrum arising from the Sun's rotation. In the Annals of the Nice Observatory he published a great atlas consisting of thirty-three maps, exhibiting in quadruplicate a subdivision of the solar spectrum under varied conditions of weather and zenith distance. He also studied the spectrum of the great comet of 1882, and by the displacement of its lines estimated that the comet was receding from the Earth at the rate of from sixty-one to seventy-six kilometers per second. The Leland prize was awarded to Thollon for a hand drawing he made of the prismatic spectrum obtained with bisulphide of carbon prisms of high dispersive power.

The character and reputation of these men, as well as others who have been quoted in these pages, must be weighed against the few who, not content with denying the existence of the canali in Mars, have in strong language abused those who accept them as veritable markings on the planet's surface.