purpose of contributing to their desire to penetrate the mysteries of fate was merely a compound of truth and falsehood, that has been denominated astrology, and the latter, ministering to the passions of most men for acquiring wealth, offering a strong temptation to its votaries, but was of no service in furthering the march of mind, although it discovered facts that were afterwards of service to the modern chemist. We may regard the Arabians more as the preservers of ancient science. Many of the inventions ascribed to them have been traced to the Indians, and were received either directly from that nation, or through the medium of the Greek philosophers, whose works were translated into the Arabic language.

The conclusion to which we may arrive from a contemplation of the state of learning in the early and middle ages is, that geometry was the only science successfully cultivated, and handed down free of any error or absurdity; all the other branches of learning were more or less imbued with mistaken views, arising generally from imperfect data. There seemed to be little respect paid to knowledge acquired from the observations of facts of daily occurrence. Abstruse studies were most esteemed. Mathematics requiring a train of deep thought, and at the same time of correct reasoning, without needing the aid of experiment requisite in physical science, enabled the cultivators to improve without any danger of perversion.

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In the study of natural philosophy a knowledge of mathematics is a sine qua non" on the part of the student, if he venture beyond the vestibule. The votary of pure mathematics will be insensibly led to the application of his favourite science for the explanation of some of the phenomena in nature, and if he be successful in solving any of their mysteries, he will be encouraged to pursue still further the research after physical truth. The ancients were thus led to apply their mathematical knowledge. The name of Archimedes is handed down as one of the brightest in ancient times. His discoveries form an important era in the history of science; and they arose from his extensive application of geometry to physics. Before his time there were no correct notions of the theory of mathematics, and he is the first who pointed VOL. II.

out the specific gravity of bodies. He is the only one of the ancients that can bear comparison with the moderns as a natural philosopher.

When learning began, after the dark ages, to revive in Europe, the mathematical lore of the ancients was sought after with great avidity. What had been effected by them in the physical sciences received also its due appreciation. Both the truth and the absurdity of their astronomy, mechanics, and other branches were swallowed without at first being questioned. But as the attention of the early moderns became more directed to scientific investigation, many of the errors of the ancients became manifest. Some of these were speedily corrected, while others, admitting of more discussion, remained for a longer period under the judgment of the the new cultivators of knowledge. Every successive age, however, dispelled more or less of these errors. The study of the pure mathematics advanced with rapid strides. Their field was augmented with numberless new discoveries. Their application to physics became every day more general; and the impulse which science had now received carried forward its votaries with a velocity never before known in its progress.

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Natural philosophy had now become science of great importance from the additions made by its early modern cultivators to what was received by them from the ancients. Among the ancients Archimedes was the first who applied geometry to physics, and thus gave it a double power. Among the first revivers of learning in Europe was Des Cartes, who applied algebra to geometry, and thus put an engine of incalculable power into the hands of the cultivator of natural philosophy. The attention of the learned was now directed to experiment, a method if investigated, but little appreciated or understood by the ancients. Galileo by his invention of the telescope opened as it were, the gates of the heavens, into which rushed a host of ardent enquirers after truth. A number of other illustrious men, at the same time, directed their attention to experiment in the other branches of physical science. The discovery of printing some time before enabled the new acquisitions to knowledge to be widely diffused, and enabled one nation to communicate its

learning to another with a rapidity never before conceived. The discovery of America not only was a successful experiment on a large scale, but it added another proof to the true system of the world, and directed in a further degree the attention of men to the examination of natural phenomena. The Reformation promoted the freedom of discussion, and enabled the laity to take part in studies, almost previously attended to by the clergy alone. But what contributed in the greatest degree to the improvement of physical science was the new path pointed out to its votaries by the illustrious Lord Bacon. His master-mind discovered the causes of error in the philosophy of the ancients, and demonstrated that as long as their mode of reasoning was pursued, it was impossible for the moderns to frame a true system of science. He asked (Playfair's Diss. Engel. Brit.) "Wherein can arise such vagueness and sterility in all the physical systems which have hitherto existed in the world? It is not certainly from anything in nature itself; for the steadiness and regularity of the laws by which it is governed clearly mark them out as objects of certain and precise knowledge. Neither can it arise from any want of ability in those who have pursued such inquiries, many of whom have been men of the highest talent and genius of the ages in which they lived; and it can therefore arise from nothing else but the perverseness and insufficiency of the methods that have been pursued. Men have sought to make a world from their own conceptions, and to draw from their own minds all the materials which they employed; but if, instead of doing so, they had consulted experience and observation, they would have had facts and not opinions to reason about, and might have ultimately arrived at the knowledge of the laws which govern the material world."

The opinions of Bacon became gradually appreciated. The calm observation of facts became in every succeeding age more attended to, and natural philosophy based upon actual experiment, and not upon the wild conceptions of the imagination.

The science of chemistry may be said to be one of the offspring of the Baconian philosophy. It is a branch of physics-the first principles of which depend wholly upon experiment. Its

progress testifies, in a remarkable degree, the importance of the inductive method of reasoning. It required a calm and patient examination of the changes produced on bodies by experiment, in order that a sufficient mass of facts might be accumulated to raise it to the rank of a science. It required its cultivators to divest themselves of all prejudices to view things as they really are, and not to set out with a previous leaning to a particular set of opinions, and to torture the results of their experiment to prop these opinions up. It is impossible it could have become a regular science under the influence of the Aristotelian philosophy. The more men reasoned from facts, the more did Chemistry advance -and it now affords one of the most brilliant examples of the happy mode pointed out by Bacon, for the improvement of knowledge.

If we sum up the results of our observations, on the progress of knowledge, we shall arrive at the conclusion, that the observation of facts was the very last object attended to in its march through successive ages, at least the calm and unprejudiced examination of facts. The learned of antiquity seemed more inclined to abstruse studies-to studies which required a precision of reasoning, which often testified their extreme ingenuity. If their first principles were correct, so were their conclusions. But that their first principles were, for the most part, erroneous, we have abundant proof, in many instances. In geometry, their first data were correct, being self-evident truths, and their conclusions were therefore just. For a succession of ages knowledge, derived from observation of the common objects in nature, was looked down upon as unworthy the regard of the philosopher. There was a consequent bar to the progress of physical knowledge.

After the revival of learning in Europe, it was not to be expected that the eyes of men could be all at once opened to the errors of the ancients. Both the truth and falsehood of the ancient philosophy were studied. The human mind was still imbued with prejudice. This, however, gradually wore away-mathematics became more extended-natural philosophy was tended and improved-chemistry was invented. We may trace the gradual

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progress of real knowledge from the first axioms of geometry, through the more advanced stages of mathematics -through the successive developments of natural philosophy, to a science resting solely upon a careful examination of facts, the science of chemistry.

Natural philosophy opened to man the field of space-it taught him to regard the motion of objects upon a grand scale-it enabled him to assign dimensions to this space, and to measure the relations of motion. Chemistry taught him to view the changes produced on bodies, by motions of their minute component particles, the measurement of which motions eludes our most subtle investigations. Natural philosophy instructed him in the external relations of the bodies in nature-chemistry in the internal. It led him, as it were, into the mind of inanimate matter.

During the last hundred years the attention paid to an unprejudiced examination of facts has been continually on the increase. Philosophers have entered upon their investigations without bias to any particular opinions. Instead of commencing their researches by laying down a favorite hypothesis, and then distorting facts to accord with it, they commenced with an impartial examination of the facts themselves, and following the suggestions of Bacon, they framed their theory by the inductive method of reasoning. By not attending to the advice of Bacon, men were inclined to imagine circumstances which have no existence in reality. They beheld nature through a medium that rarely presented her in her true form. So long as the field of physical science was limited, the liability to view nature in this manner continued; but as discovery followed discovery, the disposition to prejudice became more and more removed. For a long period men adhered to certain dogmas that had been handed down through a succession of ages, and finding it difficult to reconcile many facts in nature with these dogmas, they had recourse to hypothesis, the frequent absurdity of which paved the way to the exploding of erroneous principles, and dispelled the illusion, although supported by the authority of antiquity. Knowledge derived from poets, spreading far and wide, carried with it the examples of its own importance. The arts of life

received incalculable improvements; they, in return, aided science. They formed the passage from one branch to another-they were the illustrators of theory, by shewing its practical application. The ancient philosopher would

have disdained to lend his aid to the agriculturist, the mechanist, or the navigator. The modern man of science regards, as his proudest boast, the improvements given by him to the arts, thereby rendering man little inferior in power to the deities of the ancients.

It seems, indeed, strange that the impartial examination of facts is the result of a highly improved state of scientific knowledge. But so it is. It is only within a comparatively recent period that the point has been reached by the human mind. It has been often remarked, that the farther we advance in knowledge the more deeply are we impressed with a sense of our own ignorance. Although this may not be exactly true, still we may acknowledge that we are less confident in broaching any new theory, in proportion to the advance of the march of intellect. When our opinions can be submitted to the test of an appeal to facts, we are more cautious in stating these opinions. It is our province to study the facts attentively, so that we may not be found in the wrong.

Geometry teaches us the relations of dimension as conceived in the human mind, but which, in the abstract, has no real existence. Natural philosophy treats of the relations of existing bodies, viewed in a state of motion. Chemistry informs us of the changes produced in the bodies themselves. Mathematics, natural philosophy, and chemistry, frequently view conditions which have no existence in nature. Let us now direct our attention to a branch of knowledge which treats of the objects in nature as they really appear, which treats of facts and nothing but facts, which requires an impartial and an unbiassed examination of these facts. I refer to natural history.

Natural history it is difficult to define, from the extensive field which it presents. It may be considered as the knowledge of the bodies in nature in a state of rest, although this definition does not include all of which it treats. It is necessary, however, that in most cases, the body to be examined should

be in a state of quiescence, so far as regards the observer, in order that an accurate knowledge of it may be obtained.

The field of natural history is wide indeed; it includes all nature. But as we cannot penetrate beyond the confines of the earth which we inhabit, we must be content to become acquainted with what it contains on its surface, or in its bosom.

Having traced the progress of the human mind through the different stages of its disposition to look upon the objects in the external world, I need scarcely add that the different branches of natural history were but little attended to till of late years. It is true that among the ancients there were some philosophers who paid considerable attention to the examination of natural objects. The works of Aristotle and Pliny testify the diligence of their authors. But they viewed nature with a prejudiced eye. They imagined they discovered in objects relations which have manifestly no existence, if these objects be examined by an unbiassed observer. Among the Arabians were some learned men who might lay claim to the title of naturalists. Among the moderns the study of this department of knowledge was attended to by many of the early cultivators of learning, and many important observations have been recorded in their writings. But still prejudice was joined to their constructions of natural appearances, and it is frequently a highly amusing task to peruse their observations. Prejudice, however, became every day lessened, when once knowledge burst the fetters she had worn through so many ages-the increase of knowledge urged men forward to know more-a greater number of explorers now entered the field of nature the errors of one were corrected by another-the appeal to facts was now made in a way so as to benefit philosophy-it was made without prejudice, and may be said to form the highest refinement of the inductive method of reasoning.

We have said that, as we have no means of penetrating into space beyond the confines of the globe which we inhabit, what it contains on its surface or its interior, will furnish to us the most interesting subjects for investigation. We find its superficies divided

into land and water-we find the land presenting a variety of appearances— sometimes raised up into lofty mountains-sometimes extending into vast plains; in some places presenting a succession of rocky pinnacles—in others, exhibiting beautiful verdure, flowers, and trees. We also see the land peopled with living inhabitants; we observe that the water, on the surface of the globe, teems also both with animal and vegetable productions. If we penetrate through the superficial covering of the earth, masses of mineral riches are exposed to our view. We find the surrounding atmosphere to offer its peculiar objects of interest, and all nature to be fitted in the relation of its several parts to each other.

The study of the productions of our globe is that point, in the scale of knowledge, to which we have now arrived. The explorers of the animal, vegetable, and mineral kingdom are now abroad, and will return laden with riches. Enterprises, formerly regarded as extremely difficult, if not impracticable, have been undertaken by the students of natural history. The improvements in the arts have smoothed the paths of the cultivators of natural science, and have enabled them to penetrate the trackless ocean-to stem the rapid river, and to thread the mazes of the entangled forest with comparative facility.

An advanced state of science and art is, therefore, necessary for the perfect examination of the productions of nature. An extensive acquaintance with the other branches of knowledge is also required on the part of the observers. This connexion of the sciences is proved at every examination of nature which we make. If we explore the animal, the vegetable, or the mineral kingdom-if we mount into the atmosphere, or descend into the mine, we are impressed with the imperative necessity of our acquaintance with the different branches of physics. This demonstrates the mutual dependence of one branch of knowledge on another, and in the consideration of this dependence a field of interesting and delightful occupation is opened to us.

Let us enter this field ourselves, and let us view these mutual relations.

It will be sufficient for our present purpose if we view the relations of natural history with the other branches

of knowledge. The relations of these other branches among each other can be deduced from after consideration. It will also simplify our subject if we select some individual part of natural science, and then shew its dependence upon other kinds of knowledge. The consideration of any one point will lead to that of others, and these to more, so that we have merely to choose the particular place from which we are to start; we shall have no difficulty in our way of gathering materials for comparisons.

The part of natural history which we have selected for our purpose is geology. There is, perhaps, no portion of physical science so well suited for exemplifying the relations of its different branches with each other. It treats of the "(Lyell) successive changes that have taken place in the organic and inorganic kingdoms of nature; it enquires into the causes of these changes, and the influence which they have exerted in modifying the surface and external structure of our planet." It is the science of the earth which we inhabit-it is a science that may, at all times, be studied. If we explore the mountain or the valley, the quarry or the mine, we may every where find matter for reflection; we read the book of creation, written in characters not to be misunderstood. The language admits of no misinterpretation—it is the language of facts.

A late writer on this science remarks (Lyell):-"By these researches into the state of the earth and its inhabitants, at former periods, we acquire a more perfect knowledge of its present conditions, and more comprehensive views concerning the laws now governing its animate and inanimate productions. When we study history, we obtain a more profound insight into human nature, by instituting a comparison between the present and former states of society. We trace the long series of events which have gradually led to the actual posture of affairs, and by connecting effects with their causes, we are enabled to classify and retain in the memory a multitude of complicated relations-the various peculiarities of national character-the different degrees of moral and intellectual refinement, and numerous other circumstances, which, without historical asso

ciations, would be uninteresting, or imperfectly understood. As the present condition of nations is the result of many antecedent changes, some extremely remote, and others recentsome gradual, others sudden and violent, so the state of the natural world is the result of a long series of events, and if we would enlarge our experience of the present economy of nature, we must investigate the effects of her operations in former epochs."

As geology professes to treat of the changes that have taken place in the organic and inorganic kingdoms of nature, the student of this branch of knowledge must have a previous acquaintance, in a greater or less degree, with natural productions. The farther we proceed in the study, the more are we convinced of the necessity of our cultivating the other divisions of natural science; but what adds to the pleasure of the pursuit is the circumstance of our being able to attend to all, nearly at the same time. The study of one branch enables us to profit more in our cultivation of another.

The division of natural history that presses closest upon the attention of the geologist is mineralogy. The mineral masses of the globe are what at first arrest his attention. If he walk through a cultivated country he does not find geological phenomena of mineral substances so interesting as in districts more in a state of wild and uncultivated nature. Still there is much to claim his attention. The soil in the fields will differ in many places, and will furnish an index of the substratum. Thus he will distinguish the ferruginous clayey soil that indicates the underlying of basaltic rocks-the calcareous clayey soil resting upon mountain limestone-the chalky soil-the granitic soil, and various others. If he examine the low grounds, he will find the finer particles of clay accumulated in the lowest situations; along the slopes of the hills he will observe coarser parts of mineral substances, increasing in size as he approaches the rocky summits. If he enter into a mountain district he will discover large masses of rocks in various states of disintegration, their harder parts withstanding the assaults of ages, their softer parts separated by various causes from the harder, and carried from these elevated regions