By CHARLES LIVY WHITTLE.
This is an era of observation; in many fields and in divers countries the study of Nature from a strictly scientific standpoint is being prosecuted with results which are rapidly increasing our knowledge of the universe. This modern growth has come about as the natural rebound of the suppressed energy that has been held forcibly under subjugation during the last two thousand years, at a time when the closing echoes of the warfare between the literal interpretation of the Scriptures and science have ceased.
A review of this long battle with the forces of the Catholic and Protestant churches on the one hand, arrayed against a relatively few investigators, scattered through the last ten centuries, on the other hand, shows a record on which none can look without regret. As far as we are able to learn, there was little opposition to the study of science before the collection and translation of the old manuscripts now constituting the Alexandrian version of the Bible and the consequent upbuilding of the Jewish church. The remains of ancient Egyptian civilization show that science prior to that period, as measured by the discoveries in physics and astronomy, had attained no inconsiderable prominence; and had this people endured until the present time, uninfluenced by the strife that for many centuries racked the inhabitants of the eastern hemisphere, we should to-day be far more advanced in our understanding of the universe.
In the more progressive countries, at least, the breaking of the shackles in which the investigating mind had been imprisoned for so long has led not only to a greater number of scientific workers, but also to an increase in the fields of observation. The methods of investigation have likewise undergone a transformation. In place of deductive reasoning, even as late as a few decades in the past, conclusions and generalizations are now founded on lines of thought more largely inductive. Men of middle age are able to recall the time when even our leading institutions of learning required instruction in several branches of science to be given by one teacher. It was possible twenty-five years ago for a man of great ability to master the essentials of the leading sciences and to teach them, but under the present stimulus for investigation no one can hope to excel in more than one subject. It has thus come about that in place of the many-sided teacher of science we now have in our larger universities specialists in every subject. As the work of research progresses, the specialist—for example, in geology—is compelled by the increased scope of the information on his subject to select one branch of geology of which he shall be master. The chair of geology is now split up into economic, glacial, and mining geology, paleontology, etc., and specialists are required in each division. This breaking up is true of most other sciences. In this labyrinth of specialized subjects, and the maze of technical terms rendered necessary thereby, the people as a whole can only grope in darkness; but out of this bewildering condition of affairs, from the mass of facts collected, and the resulting generalizations and theories, there may be culled the kernel of one important principle by means of which these facts are ascertained and the generalizations made. The growth of science and its ever-ramifying divisions, and the gradual establishment of new methods of investigation, have brought forth what may be termed the science of observation; and it is through an application of the above principle that the people may be taught correctly to interpret Nature, and, by their new habit of thought, to free the brain from the tangle of superstition which is still present with most of us.
A knowledge of how to observe natural phenomena and to draw correct inferences therefrom has been the product of slow growth, while through long custom, in matters closely pertaining to our daily life, there has been observation on strictly scientific principles for centuries. Stated succinctly, natural phenomena are due to causes, one or more, simple or complex. These causes are the laws of the universe, and to arrive at an understanding of them we must free our minds of any bias and study phenomena experimentally in the laboratory, or in our daily contact with Nature. In this way a mass of facts will be gathered by the systematic observer which will be found to fall into natural groups, and by inductive reasoning the laws governing each group may be learned. It is not possible for mankind as a whole to investigate in this exhaustive manner; but it is important that the method of arriving at the laws of Nature be understood. Many and, in fact, most phenomena met with in some of the sciences, particularly those having to deal with the earth, are susceptible of correct interpretation without attempting broad generalizations, if the principles of scientific observation are brought to bear upon their solution, and it is our purpose to show by practical examples drawn from Nature how elementary students may attack and solve some of the simple problems met with on every side. It is proposed to use for illustration simple phenomena pertaining to the earth, drawn from geology and its newly constituted sister science, physical geography. These two sciences perhaps afford the greatest range of phenomena, which are accessible to every one, in whatsoever part of the earth he may reside. No part of the land surface is wanting in problems which demand explanation, and which may be attacked from the standpoint of the geologist or physical geographer, or both.
One of the most pronounced departures taking place in preparatory-school education at the present time is to be found in the prominence given to these subjects, not only in the schoolroom, but by practical experience in the laboratory of Nature, among the hills and mountains, as well. The object of this departure is twofold: the first and most important is to train the young early to observe phenomena and to interpret them; the second, in a narrower sense, is purely educational. The one inculcates a habit of thought that will be of inestimable advantage in pursuing future study; the other, without taking into consideration the element of mental training, constitutes instruction in concrete things that are matters of general education.
Before the student in the introductory schools is brought in contact with problems in the field, it is essential that he receive text-book or oral instruction in some of the geological processes giving rise to the phenomena to be studied later out of doors. In practical teaching the student is taken on excursions into the region not far removed from the school. At first some simple geological facts are shown him, often on a very small scale, but embodying principles which, when understood, lead to a ready interpretation of larger problems. Step by step the first principles are amplified by a larger and more varied class of examples, until the student is able logically to apply the reasoning in explanation of simple problems to the solution of the greater problems in physical geography and geology. In the absence of such excursions, I shall introduce a series of photographs carefully arranged to lead the reader along the same line of reasoning up to similar broad conclusions—a method which, if not so satisfactory and instructive, will at least have an educative value.
Fig. 1.—Quarry showing Fresh and Weathered Rocks.
Our first excursion will be to a locality where an open cut has been made for the purpose of carrying on quarrying operations. The accompanying photograph has been so taken as to include both the top and the bottom of the quarry (Fig. 1). Let us first inspect the rock in the lower part of the quarry. The existence of planes of fracture, or joints, crossing the rock in various directions, dividing it into blocks, early attracts our attention. The stone appears dark-colored, tough, and is seen to be made up of two or three different minerals: one is black, cleaves readily into thin plates of a translucent nature, and we easily recognize it as an iron-bearing mica, or isinglass. Another is white, and cleaves or breaks in two directions, making angles of about ninety degrees; this we know as common feldspar. The third is less easily recognized as pyroxene, another of the many minerals containing iron. Having tested our knowledge of mineralogy, we will look about and see if all the rock exposed is like that at the bottom of the quarry. As we ascend from the point indicated by the lower hammer, we notice that the dark blue rock gradually takes on a rusty hue, and its toughness has become less. Going still higher, the rusty character increases, and along joints the rock is so lacking in coherency as to fall to pieces when struck a light blow with a hammer. The central portions of the blocks, however, after we have removed the outer shell of rusty material, are seen to be like the lower rock. In the middle foreground of the picture there are shown several bowlders derived from above, which are merely these residual cores, and are known as bowlders of disintegration. These are also shown in place near the top of the picture at the extreme left. Near the top of the quarry, at a point marked by the upper hammer, the solid rock gives place to a rusty mass of loose material, traversing which the cracks may still be seen, and in which there are few indications of the solid rock[8] (see Fig. 2). This loose material when carefully examined is found to be made up of exactly the same minerals as the dense rock below, but we notice that the mica and pyroxene are rusty and that the feldspar is stained yellowish brown. The pyroxene in particular is very much changed, and quickly crumbles away in the hand. It is clear that there is every stage between the solid rock and the incoherent powder at the surface of the ground. The joint planes crossing the solid rock below may still be observed traversing the decayed portion, and also many rounded areas of rock, which are seen to be identical with the stone at the bottom of the quarry.[9]