The Progress of the Century

by Unknown

The last discovery of this kind has been that of an inner satellite of Jupiter by Barnard in 1892.

The planets from Mercury to Saturn were known to the ancients. I have already referred to the discovery of Uranus by Herschel’s giant telescope, not long before the nineteenth century was born, and of Neptune, by analysis, towards the end of the first half of the century. With regard to what modern observations have done in regard to their physical appearance, the first place in general interest must be given to Saturn and Mars.

Saturn has always been regarded as the most interesting of the planetary family on account of its unique rings. Many subdivisions of the rings, and a dusky ring, first seen by Dawes and Bond, have been discovered during the last sixty years.

The meteoritic nature of the rings was suggested by Clerk Maxwell in 1857, and Keeler’s demonstration of the truth of this view by means of the spectroscope, a few years ago, was brilliant in conception and execution.

But during the last half of the century the interest centred in Mars has been gradually increasing. The drawings made during the opposition of 1862, when compared with those made by Beer and Mädler (1830–40), made it perfectly clear that in this planet we had to deal with one strangely like our own in many respects. There were obviously land and water surfaces; the snow at the poles melted in the summer-time; clouds were seen forming from time to time, and the changing tones of the water surfaces suggested fine and rough weather.

Afterwards came the revelation of the hawk-eyed Schiaparelli, beginning in the year 1877, and his wonderful map of the planet’s surface. The land surfaces, instead of being unbroken, were cut up, as an English farm is cut up by hedges; straight lines of different breadths and tints crossed the land surfaces in all directions, and at times some of them appeared double. Schiaparelli naturally concluded that they were rivers—water channels—and being an Italian he used the appropriate word canali. This, unfortunately, as it turned out, was translated canals. Now canals are dug, ergo there were diggers. From this the demonstration, not of the habitability, but of the actual habitation, of Mars was a small step, and the best way of signalling to newly found kinsmen across some thirty millions of miles of space was discussed.

The world of science owes a debt of gratitude to Mr. Percival Lowell for having taken out to the pure air and low latitude of Arizona an eighteen-inch telescope for the sole purpose of accumulating facts tending to throw light upon this newly raised question. This he did in 1894. Schiaparelli has continued his magnificent observations through each opposition when the planet is most favorably situated for observation, and since 1896 Signor Cerulli, armed with a fifteen-inch Cooke, in the fine climate of Italy, has joined in the inquiry, so that facts are now being rapidly accumulated. It has been stated that markings similar to the strange so-called “canals” on Mars are to be seen on Mercury, Venus, and even on the satellites of Jupiter. Mr. Percival Lowell does not hesitate to proclaim himself in favor of their being due, in Mars, to an intelligent system of irrigation. Signor Cerulli claims that wherever seen they are mere optical effects. We may be well content to leave to the twentieth century a general agreement on this interesting subject.

Finally, in our survey of our own system, come comets and meteor swarms. One of the most fruitful discoveries of the century, that comets are meteor swarms, we owe to the genius of Schiaparelli, A. H. Newton, and other workers on those tiny celestial messengers which give rise to the phenomena of “falling” or “shooting” stars.

The magnificent displays of 1799, 1833, 1866, and, alas! that which failed to come in 1899, we now know must be associated with Tempel’s Comet. This is by no means the only case so far established; the connection will in the future be closer still when the orbits of the various swarms observed throughout the year shall be better known.

Comets which attract public attention by their brightness and grandeur of form are rather rare, and, in fact, only twenty-five of such have been seen since 1800. We have, however, with the great advance in instrumental equipment, been able to discover many which are scarcely visible to the naked eye, and this has swollen the number of comets very considerably. In the seventeenth century we find that only thirty-two were observed, while in the eighteenth this number was more than doubled (seventy-two). In the nineteenth century more than three hundred were placed on record, which is practically more than four times the number seen in the eighteenth.