It is idle, however, to speculate as to what the forms of life are like on Mars, for if there are any such forms our ideas and conceptions of them must be imaginary, as we cannot see them on Mars we do not know. There is yet no possibility of seeing anything on the planet less than thirty miles across, and even a city of that size, viewed through the most powerful telescope, would only be visible as a minute speck. Great as is the perfection to which our optical instruments have been brought, they have revealed nothing on the planet save the so-called canals, to indicate the presence of sentient rational beings. The canals discovered by Schiaparelli of the Milan Observatory in 1877 are so regular, outlined with such remarkable geometrical precision, that it is claimed they must be artificial and the work of a high order of intelligence. "The evidence of such work," says Professor Lowell, "points to a highly intelligent mind behind it." Can this intelligence in any way reach us, or can we express ourselves to it? Can the chasm of space which lies between the Earth and Mars be bridged--a chasm which, at the shortest, is more than thirty-five million miles across or one hundred and fifty times greater than the distance between the earth and the moon? Can the inhabitants of the Earth and Mars exchange signals? To answer the question, let us institute some comparisons. Suppose the fabled "Man in the Moon" were a real personage, we would require a telescope 800 times more powerful than the finest instrument we now have to see him, for the space penetrating power of the best telescope is not more than 300 miles and the moon is 240,000 miles distant. An object to be visible on the moon would require to be as large as the Metropolitan Insurance Building in New York, which is over 700 feet high. To see, therefore, an object on Mars by means of the telescope the object would need to have dimensions one hundred and fifty times as great as the object on the moon; in other words, before we could see a building on Mars, it would have to be one hundred and fifty times the size of the Metropolitan Building. Even if there are inhabitants there, it is not likely they have such large buildings. Assuming that there _are_ Martians, and that they are desirous of communicating with the earth by waving a flag, such a flag in order to be seen through the most powerful telescopes and when Mars is nearest, would have to be 300 miles long and 200 miles wide and be flung from a flagpole 500 miles high. The consideration of such a signal only belongs to the domain of the imagination. As an illustration, it should conclusively settle the question of the possibility or rather impossibility of signalling between the two planets.