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in various works of a professedly scientific character, yet such a sketch as we here propose may not be without its use, if it should happily succeed in removing any of the prejudices or misconceptions just referred to, and in putting the department of scientific history in such a form as may be sufficiently attractive to engage the attention of the general reader. Nor need the want of profound scientific knowledge on the part of the reader be any insuperable obstacle to his deriving some pleasure from a perusal of the records of physical discovery. For such a history is by no means a mere barren record of dates, names, and inventions. In matters of philosophical research, so close is the dependence of one truth upon another, that the history of discovery very generally presents to us the history and order of the deduction of truth. The later inventions, generally speaking, cannot be rendered intelligible till we are acquainted with the earlier: thus, in recording the history we are often actually delivering the principles of science.

In the ensuing cursory outline of such a history, it will, however, be our anxious endeavour to avoid as much as possible all dry and abstruse investigation, and to introduce no more of the technicalities of science than may be absolutely necessary for rendering our statements intelligible. In doing this we shall generally find, that the view we have to take of the progress of invention will itself supply the means of explaining those technicalities, which we shall always endeavour to illustrate in the most familiar manner which the nature of the subject will admit.

In following out an extensive enquiry, it is always a matter of great convenience to find in our subject any grand points of division naturally presenting themselves. These constitute so many landmarks, as it were, on which the eye may rest, and which assist us materially in estimating our position and the progress we are making. In attempting to sketch the history of the physical and mathematical sciences from the earliest ages to the present, we shall find three principal divi

sions naturally suggested by well marked differences of character in the science of different periods; and these intimately connected with causes which influenced the whole condition of society in those periods. These chief divisions in our subject will be,

I. The Progress of Science among the Ancients. II. Its Condition from the Middle Ages till the Time of Newton.

III. Its Advance from the Discoveries of Newton to the present Day.

Under each of these great divisions we shall pursue as perspicuous a description of the physical knowledge of those times as our limits will allow, and the nature of entirely popular illustration will permit. We shall endeavour to direct the attention of our readers mainly to those leading researches and discoveries which gave a character to the science of the age, or were remarkable as opening the way to the yet more valuable inventions of after times; and as producing the most beneficial results on the improvement of the human species in knowledge and happiness. We are, at the same time, fully aware that there will occur many subjects of considerable importance which we shall be necessitated to pass over without such notice as they deserve; but which could not be adequately discussed without entering into details absolutely inconsistent with our plan.

PART I.

THE PROGRESS OF PHYSICAL AND MATHEMATICAL

SCIENCE AMONG THE ANCIENTS.

THE first period of scientific history which we here propose to examine is one of the highest interest in every point of view. It is in a great part associated with the records of those distinguished nations whose language, history, and institutions occupy so large a share of our earliest studies: it leads us to the contemplation of those primary rudiments of scientific truth which have afforded the basis on which the whole modern superstructure has been reared; whilst the manner in which those speculations were carried on, and the errors and extravagancies with which they were often mixed up, will supply us with many useful cautions as to the only safe way of pursuing philosophical truth.

We shall find this period naturally and conveniently subdivide itself into three portions: the first reaching from the earliest records to the foundation of the school of Alexandria, about B. c. 300; the second continuing thence to the decline of that school; the third embracing the state of science in the age of the Roman empire down to the period of its dissolution.

SECTION I.

THE PROGRESS OF SCIENCE FROM THE EARLIEST RECORDS TO THE

FOUNDATION OF THE SCHOOL OF ALEXANDRIA, B. c. 300.

Origin of Science.

IN attempting to trace the vestiges of early science, we find ourselves involved in no small degree of confusion and uncertainty, among conflicting claims and fictitious

pretensions. The obscure terms again in which many of the statements of opinions, as well as facts, have been handed down to us, often leave us very much in doubt as to what were the real views or discoveries of some of the most eminent philosophers.

In the elucidation of these points the labours of the most able critics have been called forth; and though, on some such questions, considerable difference of opinion has prevailed, they have now been so fully discussed, that most of them may be considered as completely set at rest; and we can avail ourselves of the decisions of some late writers with the fullest confidence in the soundness of the reasons on which they are built. We shall therefore generally content ourselves with adopting that view of such questions, which, upon examining the authorities adduced, appears to us to possess the highest probability; always, however, stating both opinions where we feel them entitled to any thing like equal consideration.

It will assist the apprehension of the particular class of discoveries and inventions of which we here propose to treat, in the first instance, to distinguish clearly what properly fall under the designation of advances in philosophical truth. It is not every invention, however ingenious, which is properly referable to this title, nor even every process of art which may be traced to a philosophical principle; unless the knowledge of the principle really led to the practical application. The progress of the arts then will only be noticed so far as it was connected with that of science; so far as practical experience may have led to the suggestion of abstract principles, or mechanical contrivance may have resulted from philosophical reasoning.

In the earlier stages of society art must have preceded science. The immediate necessities of life first called forth the resources of invention, and it could not be till a much later period that the human mind had leisure to derive, from the objects of its daily notice, the elements of philosophical thought, or could be led to

speculate on causes and effects. Accordingly, we are prepared to expect even considerable advances in practical arts long before we have any traces of speculative science. The Mosaic history refers to the very earliest epoch, the working of metals, the construction of musical instruments, and some advance in various arts of life. But we find no distinct allusions to any culti vation of science properly so called.

Early Astronomy.

Of all sciences astronomy is probably that which may lay claim to the earliest origin; but in speaking of the astronomy of remote ages we must understand the term in a very confined and limited sense. We must neither imagine speculations of that extent to which we are now accustomed to apply the name, nor observations conducted with the accuracy and regularity which we now consider essential to confer the character of scientific results. The astronomy of the earlier ages was probably confined to noting the most obvious phenomena of the motions and eclipses of the sun and moon; the rising and setting of the principal fixed stars; and the apparent positions of the planets among them: and the means of observing were no other than such as were supplied by the use of the naked eye, and some of the simplest and rudest instruments. The progress of the sun in his apparent orbit was followed by remarking the dif ferent well known stars, as at different parts of the year they were successively lost in the twilight, and also by the variation in the length of the shadow of a suitable object, or gnomon," on a level horizontal plane, observed at the time of day when it was shortest. In order to recognise the fixed stars, the heavens were divided into constellations, or groups, in which, by the aid of a fertile imagination, some resemblance was traced out in the configuration to the shapes of the various objects whose names were assigned to them. They are alluded to by those distinctive names in the most ancient records we possess, the books of the Old Testament,

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