taught?" And yet the fruits of the new philosophy are palpable enough.

It would probably be difficult to find any circumstance more characteristic of modern civilization than the existence of a rapidly increasing class of men occupied in extending the domain of human knowledge, by experiment and reasoning hand in hand. Ancient institutions made no provision for such pursuits, and we accordingly see new ones springing up, in proportion as the number of these men increases and their activity becomes more systematic.

So

Associations, scientific societies, and academies are formed, in which investigators meet, and in many ways aid and strengthen one another. Each of these societies usually publishes periodical volumes containing the record of new observations and experiments, with the ideas and conclusions derived from them and from their comparison with previous knowledge. rapidly is knowledge accumulating by the labours of these experimental inquirers, that in one special branch of science, Chemistry, a volume of 800 to 1000 pages is every year published to describe the mere outline of the discoveries made during the year.

That the habits of mind acquired in these pursuits constitute a new and mighty power, is shown in many ways: witness the disappearance of the general belief in sorcery and witchcraft and other degrading superstitions, which had remained unshaken. by the attacks of the old philosophy. It has been well shown by a writer who traced certain features of the development of human reason (called by him Rationalism), that those beliefs, supported as they were by an overwhelming mass of direct and circumstantial evidence, were not dispelled by the elaborate and weighty arguments directed against them from time to time, but gradually vanished in proportion as men learned some few real explanations of natural phenomena, and thus acquired the germ of the scientific spirit. Logic was powerless against the superstitions, but it is equally powerless to force them upon minds trained by physical science-upon minds possessed of a few good samples of real evidence.

Witness, again, the foundations of order already laid by the scientific habit of mind in the studies of highly complex phenomena, such as those of political economy and history, formerly considered to be mere results of arbitrary action, and not amenable to any natural laws. Turn which way we will, evidences are found of the stride which the human intellect has made since Bacon proclaimed its true helps, and of the rapidly increasing power with which it is being applied to the study of natural phenomena.

There are, however, some other characteristics of the habits of mind engendered by Experimental Science, which may be found on a careful observation of the general features of its working, and which are in themselves sufficiently important to deserve attention, even if they did not happen to be suggestive of practical considerations respecting general education.

A century has not elapsed since a discovery was made which must ever rank amongst the most remarkable achievements of philosophy. From the first dawn of human reason, the process of combustion had been an object of wonder not unmixed with awe. Men gradually learnt to obtain fire and to use it for various purposes, while the nature of the process by which it was maintained continued an impenetrable mystery to them. Various substances were found, such as wood and resin, capable of feeding a flame and of keeping it alive, but the fuel gradually disappeared whilst supporting the flame, and was supposed to be destroyed by the process. Powerful intellects strove to work out an explanation of the process of combustion, and gave words instead of facts. The process remained a complete mystery till experiment was brought to aid the reasoning powers.

In the year 1774, Priestley obtained a gas by heating calx of mercury, as it was called. He found that combustible bodies burn in this gas with far greater intensity and brilliancy than they burn in common air; and that charcoal forms carbonic acid by burning either in air or in his gas. He declared it to be the active principle to which air owes its power of supporting combustion. We now know that combustion could not be explained without a knowledge of this gas, and that in reality Priestley's discovery supplied the key to the whole mystery.

His mind was, however, so constituted as to discover facts by experiment, and not to discover their place in the order of nature. Priestley's energies were not devoted to explaining the process of combustion; he was a conservative in theory, and he called his wondrous gas "Dephlogisticated air"-a name which was retained until the new theory of combustion suggested a better one.

It was, however, not long before Lavoisier turned the discovery to account in his brilliant and masterly theory of combustion. He proved that this gas, which he named oxygen, unites with the materials of combustible bodies when they are burned in the air, and that the compounds thus formed contain the oxygen and the combustible materials.

Combustion is a combination which gives off heat and light, but which does not destroy the elements taking part in it. If we burn wood or tallow or resin, and collect the products formed by their combustion, we can recover all the materials of

the wood, or tallow, or resin, and the oxygen which had united with them.

Those who know the wondrous light which this theory has thrown upon natural processes, and the vast amount of knowledge of the properties and transformations of matter which it has rendered accessible to us, cannot hesitate to class it among the most important results which man has yet attained.

It enables us to understand, to classify, and to describe an infinite number of processes of change discovered by chemists; processes of which a few only have been explained in any other way at all, and those few in a most inconvenient and clumsy way.

If we compare man's present insight into Nature (imperfect as it is), with that which he would have if this idea and its fruits were taken from him, it is like comparing daylight to the faint glimmers of starlight. We now see changes in the properties of matter which take place when different kinds come together under particular conditions, and we learn how to regulate those changes by our knowledge of their nature and conditions, where formerly our uncertain glimpses gave us confused and untrue impressions of destruction and production of different kinds of matter. We are delighted with a perception of natural forces working silently and irresistibly; and the more we observe and compare the results produced by these forces under various conditions, the more order and harmony do we find pervading the infinite variety of their manifestations.

But while our power over matter has increased, we have become aware of its limits; for we now know that we can neither destroy nor create matter, only arrange, distribute, and alter its properties.

Greatly as we must rejoice at these results, viewed as mere instruments of thought, they sink into comparative insignificance beside the method which led to their discovery, and which leads onwards to all future extensions of our knowledge. What made Priestley examine the properties of air itself and compare them with the properties of air in which a piece of charcoal had been burnt? What made him examine the gas given off by heating mercuric oxide or by heating nitre? He was cognizant of the facts and ideas established by previous investigators respecting combustion in air; and he put such questions to Nature as were suggested to him by a consideration of the results before him, receiving in reply facts of momentous importance. What made Lavoisier establish the theory of combustion by arranging Priestley's facts in natural order among other facts relating to combustion, and describing that order? Both men had the same materials of thought before them, and both were inter

preters of Nature; but two minds more different in their constitution could hardly have been, and two pieces of work more different than theirs can hardly be found. Priestley found the materials, but could not arrange or explain them. He could not even see the explanation when given by another. Lavoisier's chief merit was in arranging the facts given to him. He measured the amount of the changes which had been discovered, and his theory of combustion is the simplest statement of the result of a quantitative comparison of those changes. He had a genius for discovering order-Priestley had a genius for discovering isolated facts. The work of each harmonizes with that of the other, and their very differences made them the more necessary to one another.

Some persons might attribute this great result to chance (a common name for ignorance of causes); but those who examine carefully the course of discoveries and investigations prior to Lavoisier, will see that facts and ideas had been steadily accumulating for his theory; and that even if Priestley and he had not lived, others would doubtless have been led by the same laws of progress to make the discovery. Indeed it so happens that there lived in a little town of Sweden a quiet and modest man named Scheele, who, following quite independently the path of research, discovered oxygen nearly as soon as Priestley, and by a distinct process. Many a new truth was brought by that quiet modest man from the fountain head of knowledge, by the aid of the facts and ideas supplied by previous investigators.

When we look back upon the work of that period, free and independent as the workers felt themselves to be, and various as were their aptitudes and peculiarities of mind, we see that in all parts of the field they were moving forward in the same direction, and helping one another by an involuntary division of labour. When we examine the work which has been done more recently, we see that the results of those great men have been used as instruments of thought by the later workers, and gradually developed by further investigations, while new discoveries have been made and used in their turn as additional instruments of thought, to extend still further our means of gaining knowledge. The first discoveries alone were within reach of the limited knowledge then available for experimental purposes, and they were needed for the later work.

The mind of man has only progressed and can only progress in a particular order. It must begin with the simple and rise gradually and slowly to the complex. The very attempts to deviate from this order only serve by their failure to prove its inevitable necessity.

One other episode of modern history seems worthy of con

sideration. It is not many years since there existed among active chemists a difference of theory which was considered important. The difference was expressed by the words Type and Radical. Some explained compounds as built up upon types, others contended that they were built up from radicals. Each party appealed to facts which favoured its own view, but neither party paid much attention to the facts quoted by its opponents. We now know that each party was right, except in its denial of the other statement. Each theory describes truly a certain number of facts, and a more general theory includes them all. Our present theory required the study of compounds from the point of view of radicals and also from the point of view of types, and they are, as it were, legs upon which our more general theory stands.

Other examples might be quoted, but these may be sufficient to illustrate the fact that the methods of experimental science have exerted a controlling and directing influence of the most powerful kind over the minds of those who have adopted theman influence stronger than any differences of disposition, of climate, language, or of nation. It was some time ago an important step for men to admit the necessity of mere passive toleration of differences of opinion; but the history of philosophy teaches us the higher lesson, that varieties of theory within the limits of established truths are essential to the progress of knowledge and deserving of all encouragement. In proportion as the field of knowledge is extended, and in proportion as human activity becomes more varied, it appears that the variety of man's aptitudes and capacities tends to become greater and greater, and yet that, bound by common principles and convictions, he attains to more perfect unity of system in thoughts and in acts.

In the second part of this paper I propose to point out some of the educational uses of experimental science.

(To be continued.)

LETTER FROM CAMBRIDGE.

THE scheme for the admission of students to the university, without obliging them to be members of any particular college, has been discussed at Cambridge, but not yet voted upon. The discussion was lively; and though there is evidently much strong feeling against the scheme, still there is hope that it may be carried. The objections of those who can see in it nothing but the first admission of "infidelity and atheism," may be disre