77. THE GIBRALTAR SKULL FROM A CAVE IN GIBRALTAR 394 78. THE SKULL-TOP OF THE PRIMITIVE KIND OF MAN FROM PLEISTOCENE SANDS IN JAVA, CALLED _PITHECANTHROPUS_ 400 79. DRAWING OF THE LEFT SIDE OF THE LOWER JAW OF A MODERN EUROPEAN 404 80. OUTLINE OF THE SKULL OF THE NEANDER MAN FROM THE CHAPELLE-AUX-SAINTS 404 81. THE SKULL OF A MALE CHIMPANZEE 405 82. THE HEIDELBERG JAW 405 PLATES I. IMMATURE AND MATURE SPECIMENS OF THE COMMON EEL OF THE NATURAL SIZE _Frontispiece_ II. REAL DRAGONS. THE EXTINCT FLYING REPTILES KNOWN AS PTERODACTYLES _Facing p._ 118 SCIENCE FROM AN EASY CHAIR I SCIENCE AND PRACTICE The delight which is experienced by those who discover new things in the various branches of science is, no doubt, very great. To reveal to other men processes, properties, existences in the natural world hitherto unsuspected, or, if suspected, yet eluding the grasp of man, is to do something which gives to him who does it a sense that he is of value in the world—a sense which will uphold him and enable him to endure adversity, and even persecution, with equanimity. But there is, perhaps, a greater and more vivid satisfaction for those who do or make great and splendid things which all men can see, and for which all men are grateful. The great artist—poet, painter, builder, or musician—has this satisfaction, and so also has the man who, by a combination of personal energy and clearness of intellectual vision, applies scientific knowledge to the accomplishment of great public works, and to the acquirement of that control by mankind of the natural conditions hostile to human progress which we may call, as did Lord Bacon, “the establishing of the kingdom of man.” The men who have expelled yellow fever from Cuba and Panama have not merely done a piece of sanitary cleaning up; they have first imagined and then created, by the force of human will, directed and maintained by conviction of the reality of science, a new thing—the tropics without deadly fever, the tropics as a healthy and welcome home for the white man. That is comparable to the work of a great artist in the directness of its appeal; it is in its actual detail the result of the combination of the skill of the engineer with the foresight and absolute domination of his human agents of a military genius.