SCIENCE OF THE ROMAN PERIOD We have seen that the third century B.C. was a time when Alexandrian science was at its height, but that the second century produced also in Hipparchus at least one investigator of the very first rank; though, to be sure, Hipparchus can be called an Alexandrian only by courtesy. In the ensuing generations the Greek capital at the mouth of the Nile continued to hold its place as the centre of scientific and philosophical thought. The kingdom of the Ptolemies still flourished with at least the outward appearances of its old-time glory, and a company of grammarians and commentators of no small merit could always be found in the service of the famous museum and library; but the whole aspect of world-history was rapidly changing. Greece, after her brief day of political supremacy, was sinking rapidly into desuetude, and the hard-headed Roman in the West was making himself master everywhere. While Hipparchus of Rhodes was in his prime, Corinth, the last stronghold of the main-land of Greece, had fallen before the prowess of the Roman, and the kingdom of the Ptolemies, though still nominally free, had begun to come within the sphere of Roman influence. Just what share these political changes had in changing the aspect of Greek thought is a question regarding which difference of opinion might easily prevail; but there can be no question that, for one reason or another, the Alexandrian school as a creative centre went into a rapid decline at about the time of the Roman rise to world-power. There are some distinguished names, but, as a general rule, the spirit of the times is reminiscent rather than creative; the workers tend to collate the researches of their predecessors rather than to make new and original researches for themselves. Eratosthenes, the inventive world-measurer, was succeeded by Strabo, the industrious collator of facts; Aristarchus and Hipparchus, the originators of new astronomical methods, were succeeded by Ptolemy, the perfecter of their methods and the systematizer of their knowledge. Meanwhile, in the West, Rome never became a true culture-centre. The great genius of the Roman was political; the Augustan Age produced a few great historians and poets, but not a single great philosopher or creative devotee of science. Cicero, Lucian, Seneca, Marcus Aurelius, give us at best a reflection of Greek philosophy. Pliny, the one world-famous name in the scientific annals of Rome, can lay claim to no higher credit than that of a marvellously industrious collector of facts--the compiler of an encyclopaedia which contains not one creative touch. All in all, then, this epoch of Roman domination is one that need detain the historian of science but a brief moment. With the culmination of Greek effort in the so-called Hellenistic period we have seen ancient science at its climax. The Roman period is but a time of transition, marking, as it were, a plateau on the slope between those earlier heights and the deep, dark valleys of the Middle Ages. Yet we cannot quite disregard the efforts of such workers as those we have just named. Let us take a more specific glance at their accomplishments.
STRABO THE GEOGRAPHER The earliest of these workers in point of time is Strabo. This most famous of ancient geographers was born in Amasia, Pontus, about 63 B.C., and lived to the year 24 A.D., living, therefore, in the age of Caesar and Augustus, during which the final transformation in the political position of the kingdom of Egypt was effected. The name of Strabo in a modified form has become popularized through a curious circumstance. The geographer, it appears, was afflicted with a peculiar squint of the eyes, hence the name strabismus, which the modern oculist applies to that particular infirmity. Fortunately, the great geographer has not been forced to depend upon hearsay evidence for recognition. His comprehensive work on geography has been preserved in its entirety, being one of the few expansive classical writings of which this is true. The other writings of Strabo, however, including certain histories of which reports have come down to us, are entirely lost. The geography is in many ways a remarkable book. It is not, however, a work in which any important new principles are involved. Rather is it typical of its age in that it is an elaborate compilation and a critical review of the labors of Strabo's predecessors. Doubtless it contains a vast deal of new information as to the details of geography--precise areas and distance, questions of geographical locations as to latitude and zones, and the like. But however important these details may have been from a contemporary stand-point, they, of course, can have nothing more than historical interest to posterity. The value of the work from our present stand-point is chiefly due to the criticisms which Strabo passes upon his forerunners, and to the incidental historical and scientific references with which his work abounds. Being written in this closing period of ancient progress, and summarizing, as it does, in full detail the geographical knowledge of the time, it serves as an important guide-mark for the student of the progress of scientific thought. We cannot do better than briefly to follow Strabo in his estimates and criticisms of the work of his predecessors, taking note thus of the point of view from which he himself looked out upon the world. We shall thus gain a clear idea as to the state of scientific geography towards the close of the classical epoch. "If the scientific investigation of any subject be the proper avocation of the philosopher," says Strabo, "geography, the science of which we propose to treat, is certainly entitled to a high place; and this is evident from many considerations. They who first undertook to handle the matter were distinguished men. Homer, Anaximander the Milesian, and Hecaeus (his fellow-citizen according to Eratosthenes), Democritus, Eudoxus, Dicaearchus, and Ephorus, with many others, and after these, Eratosthenes, Polybius, and Posidonius, all of them philosophers. Nor is the great learning through which alone this subject can be approached possessed by any but a person acquainted with both human and divine things, and these attainments constitute what is called philosophy. In addition to its vast importance in regard to social life and the art of government, geography unfolds to us a celestial phenomena, acquaints us with the occupants of the land and ocean, and the vegetation, fruits, and peculiarities of the various quarters of the earth, a knowledge of which marks him who cultivates it as a man earnest in the great problem of life and happiness." Strabo goes on to say that in common with other critics, including Hipparchus, he regards Homer as the first great geographer. He has much to say on the geographical knowledge of the bard, but this need not detain us. We are chiefly concerned with his comment upon his more recent predecessors, beginning with Eratosthenes. The constant reference to this worker shows the important position which he held. Strabo appears neither as detractor nor as partisan, but as one who earnestly desires the truth. Sometimes he seems captious in his criticisms regarding some detail, nor is he always correct in his emendations of the labors of others; but, on the whole, his work is marked by an evident attempt at fairness. In reading his book, however, one is forced to the conclusion that Strabo is an investigator of details, not an original thinker. He seems more concerned with precise measurements than with questionings as to the open problems of his science. Whatever he accepts, then, may be taken as virtually the stock doctrine of the period. "As the size of the earth," he says, "has been demonstrated by other writers, we shall here take for granted and receive as accurate what they have advanced. We shall also assume that the earth is spheroidal, that its surface is likewise spheroidal and, above all, that bodies have a tendency towards its centre, which latter point is clear to the perception of the most average understanding. However, we may show summarily that the earth is spheroidal, from the consideration that all things, however distant, tend to its centre, and that every body is attracted towards its centre by gravity. This is more distinctly proved from observations of the sea and sky, for here the evidence of the senses and common observation is alone requisite. The convexity of the sea is a further proof of this to those who have sailed, for they cannot perceive lights at a distance when placed at the same level as their eyes, and if raised on high they at once become perceptible to vision though at the same time farther removed. So when the eye is raised it sees what before was utterly imperceptible. Homer speaks of this when he says:
" 'Lifted up on the vast wave he quickly beheld afar.' Sailors as they approach their destination behold the shore continually raising itself to their view, and objects which had at first seemed low begin to lift themselves. Our gnomons, also, are, among other things, evidence of the revolution of the heavenly bodies, and common-sense at once shows us that if the depth of the earth were infinite such a revolution could not take place." Elsewhere Strabo criticises Eratosthenes for having entered into a long discussion as to the form of the earth. This matter, Strabo thinks, "should have been disposed of in the compass of a few words." Obviously this doctrine of the globe's sphericity had, in the course of 600 years, become so firmly established among the Greek thinkers as to seem almost axiomatic. We shall see later on how the Western world made a curious recession from this seemingly secure position under stimulus of an Oriental misconception. As to the size of the globe, Strabo is disposed to accept without particular comment the measurements of Eratosthenes. He speaks, however, of "more recent measurements," referring in particular to that adopted by Posidonius, according to which the circumference is only about one hundred and eighty thousand stadia. Posidonius, we may note in passing, was a contemporary and friend of Cicero, and hence lived shortly before the time of Strabo. His measurement of the earth was based on observations of a star which barely rose above the southern horizon at Rhodes as compared with the height of the same star when observed at Alexandria. This measurement of Posidonius, together with the even more famous measurement of Eratosthenes, appears to have been practically the sole guide as to the size of the earth throughout the later periods of antiquity, and, indeed, until the later Middle Ages. As becomes a writer who is primarily geographer and historian rather than astronomer, Strabo shows a much keener interest in the habitable portions of the globe than in the globe as a whole. He assures us that this habitable portion of the earth is a great island, "since wherever men have approached the termination of the land, the sea, which we designate ocean, has been met with, and reason assures us of the similarity of this place which our senses have not been tempted to survey." He points out that whereas sailors have not circumnavigated the globe, that they had not been prevented from doing so by any continent, and it seems to him altogether unlikely that the Atlantic Ocean is divided into two seas by narrow isthmuses so placed as to prevent circumnavigation. "How much more probable that it is confluent and uninterrupted. This theory," he adds, "goes better with the ebb and flow of the ocean. Moreover (and here his reasoning becomes more fanciful), the greater the amount of moisture surrounding the earth, the easier would the heavenly bodies be supplied with vapor from thence." Yet he is disposed to believe, following Plato, that the tradition "concerning the island of Atlantos might be received as something more than idle fiction, it having been related by Solon, on the authority of the Egyptian priests, that this island, almost as large as a continent, was formerly in existence although now it had disappeared." In a word, then, Strabo entertains no doubt whatever that it would be possible to sail around the globe from Spain to India. Indeed, so matter-of-fact an inference was this that the feat of Columbus would have seemed less surprising in the first century of our era than it did when actually performed in the fifteenth century. The terrors of the great ocean held the mariner back, rather than any doubt as to where he would arrive at the end of the voyage. Coupled with the idea that the habitable portion of the earth is an island, there was linked a tolerably definite notion as to the shape of this island. This shape Strabo likens to a military cloak. The comparison does not seem peculiarly apt when we are told presently that the length of the habitable earth is more than twice its breadth. This idea, Strabo assures us, accords with the most accurate observations "both ancient and modern." These observations seemed to show that it is not possible to live in the region close to the equator, and that, on the other hand, the cold temperature sharply limits the habitability of the globe towards the north. All the civilization of antiquity clustered about the Mediterranean, or extended off towards the east at about the same latitude. Hence geographers came to think of the habitable globe as having the somewhat lenticular shape which a crude map of these regions suggests. We have already had occasion to see that at an earlier day Anaxagoras was perhaps influenced in his conception of the shape of the earth by this idea, and the constant references of Strabo impress upon us the thought that this long, relatively narrow area of the earth's surface is the only one which can be conceived of as habitable. Strabo had much to tell us concerning zones, which, following Posidonius, he believes to have been first described by Parmenides. We may note, however, that other traditions assert that both Thales and Pythagoras had divided the earth into zones. The number of zones accepted by Strabo is five, and he criticises Polybius for making the number six. The five zones accepted by Strabo are as follows: the uninhabitable torrid zone lying in the region of the equator; a zone on either side of this extending to the tropic; and then the temperate zones extending in either direction from the tropic to the arctic regions. There seems to have been a good deal of dispute among the scholars of the time as to the exact arrangement of these zones, but the general idea that the north-temperate zone is the part of the earth with which the geographer deals seemed clearly established. That the south-temperate zone would also present a habitable area is an idea that is sometimes suggested, though seldom or never distinctly expressed. It is probable that different opinions were held as to this, and no direct evidence being available, a cautiously scientific geographer like Strabo would naturally avoid the expression of an opinion regarding it. Indeed, his own words leave us somewhat in doubt as to the precise character of his notion regarding the zones. Perhaps we shall do best to quote them: "Let the earth be supposed to consist of five zones. (1) The equatorial circle described around it. (2) Another parallel to this, and defining the frigid zone of the northern hemisphere. (3) A circle passing through the poles and cutting the two preceding circles at right- angles. The northern hemisphere contains two quarters of the earth, which are bounded by the equator and circle passing through the poles. Each of these quarters should be supposed to contain a four-sided district, its northern side being of one-half of the parallel next the pole, its southern by the half of the equator, and its remaining sides by two segments of the circle drawn through the poles, opposite to each other, and equal in length. In one of these (which of them is of no consequence) the earth which we inhabit is situated, surrounded by a sea and similar to an island. This, as we said before, is evident both to our senses and to our reason. But let any one doubt this, it makes no difference so far as geography is concerned whether you believe the portion of the earth which we inhabit to be an island or only admit what we know from experience --namely, that whether you start from the east or the west you may sail all around it. Certain intermediate spaces may have been left (unexplored), but these are as likely to be occupied by sea as uninhabited land. The object of the geographer is to describe known countries. Those which are unknown he passes over equally with those beyond the limits of the inhabited earth. It will, therefore, be sufficient for describing the contour of the island we have been speaking of, if we join by a right line the outmost points which, up to this time, have been explored by voyagers along the coast on either side." We may pass over the specific criticisms of Strabo upon various explorations that seem to have been of great interest to his contemporaries, including an alleged trip of one Eudoxus out into the Atlantic, and the journeyings of Pytheas in the far north. It is Pytheas, we may add, who was cited by Hipparchus as having made the mistaken observation that the length of the shadow of the gnomon is the same at Marseilles and Byzantium, hence that these two places are on the same parallel. Modern commentators have defended Pytheas as regards this observation, claiming that it was Hipparchus and not Pytheas who made the second observation from which the faulty induction was drawn. The point is of no great significance, however, except as showing that a correct method of determining the problems of latitude had thus early been suggested. That faulty observations and faulty application of the correct principle should have been made is not surprising. Neither need we concern ourselves with the details as to the geographical distances, which Strabo found so worthy of criticism and controversy. But in leaving the great geographer we may emphasize his point of view and that of his contemporaries by quoting three fundamental principles which he reiterates as being among the "facts established by natural philosophers." He tells us that "(1) The earth and heavens are spheroidal. (2) The tendency of all bodies having weight is towards a centre. (3) Further, the earth being spheroidal and having the same centre as the heavens, is motionless, as well as the axis that passes through both it and the heavens. The heavens turn round both the earth and its axis, from east to west. The fixed stars turn round with it at the same rate as the whole. These fixed stars follow in their course parallel circles, the principal of which are the equator, two tropics, and the arctic circles; while the planets, the sun, and the moon describe certain circles comprehended within the zodiac." Here, then, is a curious mingling of truth and error. The Pythagorean doctrine that the earth is round had become a commonplace, but it would appear that the theory of Aristarchus, according to which the earth is in motion, has been almost absolutely forgotten. Strabo does not so much as refer to it; neither, as we shall see, is it treated with greater respect by the other writers of the period.
TWO FAMOUS EXPOSITORS--PLINY AND PTOLEMY While Strabo was pursuing his geographical studies at Alexandria, a young man came to Rome who was destined to make his name more widely known in scientific annals than that of any other Latin writer of antiquity. This man was Plinius Secundus, who, to distinguish him from his nephew, a famous writer in another field, is usually spoken of as Pliny the Elder. There is a famous story to the effect that the great Roman historian Livy on one occasion addressed a casual associate in the amphitheatre at Rome, and on learning that the stranger hailed from the outlying Spanish province of the empire, remarked to him, "Yet you have doubtless heard of my writings even there." "Then," replied the stranger, "you must be either Livy or Pliny." The anecdote illustrates the wide fame which the Roman naturalist achieved in his own day. And the records of the Middle Ages show that this popularity did not abate in succeeding times. Indeed, the Natural History of Pliny is one of the comparatively few bulky writings of antiquity that the efforts of copyists have preserved to us almost entire. It is, indeed, a remarkable work and eminently typical of its time; but its author was an industrious compiler, not a creative genius. As a monument of industry it has seldom been equalled, and in this regard it seems the more remarkable inasmuch as Pliny was a practical man of affairs who occupied most of his life as a soldier fighting the battles of the empire. He compiled his book in the leisure hours stolen from sleep, often writing by the light of the camp-fire. Yet he cites or quotes from about four thousand works, most of which are known to us only by his references. Doubtless Pliny added much through his own observations. We know how keen was his desire to investigate, since he lost his life through attempting to approach the crater of Vesuvius on the occasion of that memorable eruption which buried the cities of Herculaneum and Pompeii. Doubtless the wandering life of the soldier had given Pliny abundant opportunity for personal observation in his favorite fields of botany and zoology. But the records of his own observations are so intermingled with knowledge drawn from books that it is difficult to distinguish the one from the other. Nor does this greatly matter, for whether as closet-student or field-naturalist, Pliny's trait of mind is essentially that of the compiler. He was no philosophical thinker, no generalizer, no path-maker in science. He lived at the close of a great progressive epoch of thought; in one of those static periods when numberless observers piled up an immense mass of details which might advantageously be sorted into a kind of encyclopaedia. Such an encyclopaedia is the so-called Natural History of Pliny. It is a vast jumble of more or less uncritical statements regarding almost every field of contemporary knowledge. The descriptions of animals and plants predominate, but the work as a whole would have been immensely improved had the compiler shown a more critical spirit. As it is, he seems rather disposed to quote any interesting citation that he comes across in his omnivorous readings, shielding himself behind an equivocal "it is said," or "so and so alleges." A single illustration will suffice to show what manner of thing is thought worthy of repetition. "It is asserted," he says, "that if the fish called a sea-star is smeared with the fox's blood and then nailed to the upper lintel of the door, or to the door itself, with a copper nail, no noxious spell will be able to obtain admittance, or, at all events, be productive of any ill effects." It is easily comprehensible that a work fortified with such practical details as this should have gained wide popularity. Doubtless the natural histories of our own day would find readier sale were they to pander to various superstitions not altogether different from that here suggested. The man, for example, who believes that to have a black cat cross his path is a lucky omen would naturally find himself attracted by a book which took account of this and similar important details of natural history. Perhaps, therefore, it was its inclusion of absurdities, quite as much as its legitimate value, that gave vogue to the celebrated work of Pliny. But be that as it may, the most famous scientist of Rome must be remembered as a popular writer rather than as an experimental worker. In the history of the promulgation of scientific knowledge his work is important; in the history of scientific principles it may virtually be disregarded.
PTOLEMY, THE LAST GREAT ASTRONOMER OF ANTIQUITY Almost the same thing may be said of Ptolemy, an even more celebrated writer, who was born not very long after the death of Pliny. The exact dates of Ptolemy's life are not known, but his recorded observations extend to the year 151 A.D. He was a working astronomer, and he made at least one original discovery of some significance--namely, the observation of a hitherto unrecorded irregularity of the moon's motion, which came to be spoken of as the moon's evection. This consists of periodical aberrations from the moon's regular motion in its orbit, which, as we now know, are due to the gravitation pull of the sun, but which remained unexplained until the time of Newton. Ptolemy also made original observations as to the motions of the planets. He is, therefore, entitled to a respectable place as an observing astronomer; but his chief fame rests on his writings. His great works have to do with geography and astronomy. In the former field he makes an advance upon Strabo, citing the latitude of no fewer than five thousand places. In the field of astronomy, his great service was to have made known to the world the labors of Hipparchus. Ptolemy has been accused of taking the star-chart of his great predecessor without due credit, and indeed it seems difficult to clear him of this charge. Yet it is at least open to doubt whether be intended any impropriety, inasmuch as be all along is sedulous in his references to his predecessor. Indeed, his work might almost be called an exposition of the astronomical doctrines of Hipparchus. No one pretends that Ptolemy is to be compared with the Rhodesian observer as an original investigator, but as a popular expounder his superiority is evidenced in the fact that the writings of Ptolemy became practically the sole astronomical text-book of the Middle Ages both in the East and in the West, while the writings of Hipparchus were allowed to perish. The most noted of all the writings of Ptolemy is the work which became famous under the Arabic name of Almagest. This word is curiously derived from the Greek title , "the greatest construction," a name given the book to distinguish it from a work on astrology in four books by the same author. For convenience of reference it came to be spoken of merely as , from which the Arabs form the title Tabair al Magisthi, under which title the book was published in the year 827. From this it derived the word Almagest, by which Ptolemy's work continued to be known among the Arabs, and subsequently among Europeans when the book again became known in the West. Ptolemy's book, as has been said, is virtually an elaboration of the doctrines of Hipparchus. It assumes that the earth is the fixed centre of the solar system, and that the stars and planets revolve about it in twenty-four hours, the earth being, of course, spherical. It was not to be expected that Ptolemy should have adopted the heliocentric idea of Aristarchus. Yet it is much to be regretted that he failed to do so, since the deference which was accorded his authority throughout the Middle Ages would doubtless have been extended in some measure at least to this theory as well, had he championed it. Contrariwise, his unqualified acceptance of the geocentric doctrine sufficed to place that doctrine beyond the range of challenge. The Almagest treats of all manner of astronomical problems, but the feature of it which gained it widest celebrity was perhaps that which has to do with eccentrics and epicycles. This theory was, of course, but an elaboration of the ideas of Hipparchus; but, owing to the celebrity of the expositor, it has come to be spoken of as the theory of Ptolemy. We have sufficiently detailed the theory in speaking of Hipparchus. It should be explained, however, that, with both Hipparchus and Ptolemy, the theory of epicycles would appear to have been held rather as a working hypothesis than as a certainty, so far as the actuality of the minor spheres or epicycles is concerned. That is to say, these astronomers probably did not conceive either the epicycles or the greater spheres as constituting actual solid substances. Subsequent generations, however, put this interpretation upon the theory, conceiving the various spheres as actual crystalline bodies. It is difficult to imagine just how the various epicycles were supposed to revolve without interfering with the major spheres, but perhaps this is no greater difficulty than is presented by the alleged properties of the ether, which physicists of to-day accept as at least a working hypothesis. We shall see later on how firmly the conception of concentric crystalline spheres was held to, and that no real challenge was ever given that theory until the discovery was made that comets have an orbit that must necessarily intersect the spheres of the various planets. Ptolemy's system of geography in eight books, founded on that of Marinus of Tyre, was scarcely less celebrated throughout the Middle Ages than the Almagest. It contained little, however, that need concern us here, being rather an elaboration of the doctrines to which we have already sufficiently referred. None of Ptolemy's original manuscripts has come down to us, but there is an alleged fifth-century manuscript attributed to Agathadamon of Alexandria which has peculiar interest because it contains a series of twenty-seven elaborately colored maps that are supposed to be derived from maps drawn up by Ptolemy himself. In these maps the sea is colored green, the mountains red or dark yellow, and the land white. Ptolemy assumed that a degree at the equator was 500 stadia instead of 604 stadia in length. We are not informed as to the grounds on which this assumption was made, but it has been suggested that the error was at least partially instrumental in leading to one very curious result. "Taking the parallel of Rhodes," says Donaldson, "he calculated the longitudes from the Fortunate Islands to Cattigara or the west coast of Borneo at 180 degrees, conceiving this to be one-half the circumference of the globe. The real distance is only 125 degrees or 127 degrees, so that his measurement is wrong by one third of the whole, one-sixth for the error in the measurement of a degree and one-sixth for the errors in measuring the distance geometrically. These errors, owing to the authority attributed to the geography of Ptolemy in the Middle Ages, produced a consequence of the greatest importance. They really led to the discovery of America. For the design of Columbus to sail from the west of Europe to the east of Asia was founded on the supposition that the distance was less by one third than it really was." This view is perhaps a trifle fanciful, since there is nothing to suggest that the courage of Columbus would have balked at the greater distance, and since the protests of the sailors, which nearly thwarted his efforts, were made long before the distance as estimated by Ptolemy had been covered; nevertheless it is interesting to recall that the great geographical doctrines, upon which Columbus must chiefly have based his arguments, had been before the world in an authoritative form practically unheeded for more than twelve hundred years, awaiting a champion with courage enough to put them to the test.
GALEN--THE LAST GREAT ALEXANDRIAN There is one other field of scientific investigation to which we must give brief attention before leaving the antique world. This is the field of physiology and medicine. In considering it we shall have to do with the very last great scientist of the Alexandrian school. This was Claudius Galenus, commonly known as Galen, a man whose fame was destined to eclipse that of all other physicians of antiquity except Hippocrates, and whose doctrines were to have the same force in their field throughout the Middle Ages that the doctrines of Aristotle had for physical science. But before we take up Galen's specific labors, it will be well to inquire briefly as to the state of medical art and science in the Roman world at the time when the last great physician of antiquity came upon the scene. The Romans, it would appear, had done little in the way of scientific discoveries in the field of medicine, but, nevertheless, with their practicality of mind, they had turned to better account many more of the scientific discoveries of the Greeks than did the discoverers themselves. The practising physicians in early Rome were mostly men of Greek origin, who came to the capital after the overthrow of the Greeks by the Romans. Many of them were slaves, as earning money by either bodily or mental labor was considered beneath the dignity of a Roman citizen. The wealthy Romans, who owned large estates and numerous slaves, were in the habit of purchasing some of these slave doctors, and thus saving medical fees by having them attend to the health of their families. By the beginning of the Christian era medicine as a profession had sadly degenerated, and in place of a class of physicians who practised medicine along rational or legitimate lines, in the footsteps of the great Hippocrates, there appeared great numbers of "specialists," most of them charlatans, who pretended to possess supernatural insight in the methods of treating certain forms of disease. These physicians rightly earned the contempt of the better class of Romans, and were made the object of many attacks by the satirists of the time. Such specialists travelled about from place to place in much the same manner as the itinerant "Indian doctors" and "lightning tooth-extractors" do to-day. Eye-doctors seem to have been particularly numerous, and these were divided into two classes, eye-surgeons and eye-doctors proper. The eye-surgeon performed such operations as cauterizing for ingrowing eyelashes and operating upon growths about the eyes; while the eye-doctors depended entirely upon salves and lotions. These eye-salves were frequently stamped with the seal of the physician who compounded them, something like two hundred of these seals being still in existence. There were besides these quacks, however, reputable eye-doctors who must have possessed considerable skill in the treatment of certain ophthalmias. Among some Roman surgical instruments discovered at Rheims were found also some drugs employed by ophthalmic surgeons, and an analysis of these show that they contained, among other ingredients, some that are still employed in the treatment of certain affections of the eye. One of the first steps taken in recognition of the services of physicians was by Julius Caesar, who granted citizenship to all physicians practising in Rome. This was about fifty years before the Christian era, and from that time on there was a gradual improvement in the attitude of the Romans towards the members of the medical profession. As the Romans degenerated from a race of sturdy warriors and became more and more depraved physically, the necessity for physicians made itself more evident. Court physicians, and physicians-in-ordinary, were created by the emperors, as were also city and district physicians. In the year 133 A.D. Hadrian granted immunity from taxes and military service to physicians in recognition of their public services. The city and district physicians, known as the archiatri populaires, treated and cared for the poor without remuneration, having a position and salary fixed by law and paid them semi-annually. These were honorable positions, and the archiatri were obliged to give instruction in medicine, without pay, to the poor students. They were allowed to receive fees and donations from their patients, but not, however, until the danger from the malady was past. Special laws were enacted to protect them, and any person subjecting them to an insult was liable to a fine "not exceeding one thousand pounds." An example of Roman practicality is shown in the method of treating hemorrhage, as described by Aulus Cornelius Celsus (53 B.C. to 7 A.D.). Hippocrates and Hippocratic writers treated hemorrhage by application of cold, pressure, styptics, and sometimes by actual cauterizing; but they knew nothing of the simple method of stopping a hemorrhage by a ligature tied around the bleeding vessel. Celsus not only recommended tying the end of the injured vessel, but describes the method of applying two ligatures before the artery is divided by the surgeon--a common practice among surgeons at the present time. The cut is made between these two, and thus hemorrhage is avoided from either end of the divided vessel. Another Roman surgeon, Heliodorus, not only describes the use of the ligature in stopping hemorrhage, but also the practice of torsion--twisting smaller vessels, which causes their lining membrane to contract in a manner that produces coagulation and stops hemorrhage. It is remarkable that so simple and practical a method as the use of the ligature in stopping hemorrhage could have gone out of use, once it had been discovered; but during the Middle Ages it was almost entirely lost sight of, and was not reintroduced until the time of Ambroise Pare, in the sixteenth century. Even at a very early period the Romans recognized the advantage of surgical methods on the field of battle. Each soldier was supplied with bandages, and was probably instructed in applying them, something in the same manner as is done now in all modern armies. The Romans also made use of military hospitals and had established a rude but very practical field-ambulance service. "In every troop or bandon of two or four hundred men, eight or ten stout fellows were deputed to ride immediately behind the fighting-line to pick up and rescue the wounded, for which purpose their saddles had two stirrups on the left side, while they themselves were provided with water-flasks, and perhaps applied temporary bandages. They were encouraged by a reward of a piece of gold for each man they rescued. 'Noscomi' were male nurses attached to the military hospitals, but not inscribed 'on strength' of the legions, and were probably for the most part of the servile class." From the time of the early Alexandrians, Herophilus and Erasistratus, whose work we have already examined, there had been various anatomists of some importance in the Alexandrian school, though none quite equal to these earlier workers. The best-known names are those of Celsus (of whom we have already spoken), who continued the work of anatomical investigation, and Marinus, who lived during the reign of Nero, and Rufus of Ephesus. Probably all of these would have been better remembered by succeeding generations had their efforts not been eclipsed by those of Galen. This greatest of ancient anatomists was born at Pergamus of Greek parents. His father, Nicon, was an architect and a man of considerable ability. Until his fifteenth year the youthful Galen was instructed at home, chiefly by his father; but after that time he was placed under suitable teachers for instruction in the philosophical systems in vogue at that period. Shortly after this, however, the superstitious Nicon, following the interpretations of a dream, decided that his son should take up the study of medicine, and placed him under the instruction of several learned physicians. Galen was a tireless worker, making long tours into Asia Minor and Palestine to improve himself in pharmacology, and studying anatomy for some time at Alexandria. He appears to have been full of the superstitions of the age, however, and early in his career made an extended tour into western Asia in search of the chimerical "jet-stone"--a stone possessing the peculiar qualities of "burning with a bituminous odor and supposed to possess great potency in curing such diseases as epilepsy, hysteria, and gout." By the time he had reached his twenty-eighth year he had perfected his education in medicine and returned to his home in Pergamus. Even at that time he had acquired considerable fame as a surgeon, and his fellow-citizens showed their confidence in his ability by choosing him as surgeon to the wounded gladiators shortly after his return to his native city. In these duties his knowledge of anatomy aided him greatly, and he is said to have healed certain kinds of wounds that had previously baffled the surgeons. In the time of Galen dissections of the human body were forbidden by law, and he was obliged to confine himself to dissections of the lower animals. He had the advantage, however, of the anatomical works of Herophilus and Erasistratus, and he must have depended upon them in perfecting his comparison between the anatomy of men and the lower animals. It is possible that he did make human dissections surreptitiously, but of this we have no proof. He was familiar with the complicated structure of the bones of the cranium. He described the vertebrae clearly, divided them into groups, and named them after the manner of anatomists of to-day. He was less accurate in his description of the muscles, although a large number of these were described by him. Like all anatomists before the time of Harvey, he had a very erroneous conception of the circulation, although he understood that the heart was an organ for the propulsion of blood, and he showed that the arteries of the living animals did not contain air alone, as was taught by many anatomists. He knew, also, that the heart was made up of layers of fibres that ran in certain fixed directions--that is, longitudinal, transverse, and oblique; but he did not recognize the heart as a muscular organ. In proof of this he pointed out that all muscles require rest, and as the heart did not rest it could not be composed of muscular tissue. Many of his physiological experiments were conducted upon scientific principles. Thus he proved that certain muscles were under the control of definite sets of nerves by cutting these nerves in living animals, and observing that the muscles supplied by them were rendered useless. He pointed out also that nerves have no power in themselves, but merely conduct impulses to and from the brain and spinal-cord. He turned this peculiar knowledge to account in the case of a celebrated sophist, Pausanias, who had been under the treatment of various physicians for a numbness in the fourth and fifth fingers of his left hand. These physicians had been treating this condition by applications of poultices to the hand itself. Galen, being called in consultation, pointed out that the injury was probably not in the hand itself, but in the ulner nerve, which controls sensation in the fourth and fifth fingers. Surmising that the nerve must have been injured in some way, he made careful inquiries of the patient, who recalled that he had been thrown from his chariot some time before, striking and injuring his back. Acting upon this information, Galen applied stimulating remedies to the source of the nerve itself--that is, to the bundle of nerve-trunks known as the brachial plexus, in the shoulder. To the surprise and confusion of his fellow-physicians, this method of treatment proved effective and the patient recovered completely in a short time. Although the functions of the organs in the chest were not well understood by Galen, he was well acquainted with their anatomy. He knew that the lungs were covered by thin membrane, and that the heart was surrounded by a sac of very similar tissue. He made constant comparisons also between these organs in different animals, as his dissections were performed upon beasts ranging in size from a mouse to an elephant. The minuteness of his observations is shown by the fact that he had noted and described the ring of bone found in the hearts of certain animals, such as the horse, although not found in the human heart or in most animals. His description of the abdominal organs was in general accurate. He had noted that the abdominal cavity was lined with a peculiar saclike membrane, the peritoneum, which also surrounded most of the organs contained in the cavity, and he made special note that this membrane also enveloped the liver in a peculiar manner. The exactness of the last observation seems the more wonderful when we reflect that even to-day the medical, student finds a correct understanding of the position of the folds of the peritoneum one of the most difficult subjects in anatomy. As a practical physician he was held in the highest esteem by the Romans. The Emperor Marcus Aurelius called him to Rome and appointed him physician-inordinary to his son Commodus, and on special occasions Marcus Aurelius himself called in Galen as his medical adviser. On one occasion, the three army surgeons in attendance upon the emperor declared that he was about to be attacked by a fever. Galen relates how "on special command I felt his pulse, and finding it quite normal, considering his age and the time of day, I declared it was no fever but a digestive disorder, due to the food he had eaten, which must be converted into phlegm before being excreted. Then the emperor repeated three times, 'That's the very thing,' and asked what was to be done. I answered that I usually gave a glass of wine with pepper sprinkled on it, but for you kings we only use the safest remedies, and it will suffice to apply wool soaked in hot nard ointment locally. The emperor ordered the wool, wine, etc., to be brought, and I left the room. His feet were warmed by rubbing with hot hands, and after drinking the peppered wine, he said to Pitholaus (his son's tutor), 'We have only one doctor, and that an honest one,' and went on to describe me as the first of physicians and the only philosopher, for he had tried many before who were not only lovers of money, but also contentious, ambitious, envious, and malignant." It will be seen from this that Galen had a full appreciation of his own abilities as a physician, but inasmuch as succeeding generations for a thousand years concurred in the alleged statement made by Marcus Aurelius as to his ability, he is perhaps excusable for his open avowal of his belief in his powers. His faith in his accuracy in diagnosis and prognosis was shown when a colleague once said to him, "I have used the prognostics of Hippocrates as well as you. Why can I not prognosticate as well as you?" To this Galen replied, "By God's help I have never been deceived in my prognosis." It is probable that this statement was made in the heat of argument, and it is hardly to be supposed that he meant it literally. His systems of treatment were far in advance of his theories regarding the functions of organs, causes of disease, etc., and some of them are still first principles with physicians. Like Hippocrates, he laid great stress on correct diet, exercise, and reliance upon nature. "Nature is the overseer by whom health is supplied to the sick," he says. "Nature lends her aid on all sides, she decides and cures diseases. No one can be saved unless nature conquers the disease, and no one dies unless nature succumbs." From the picture thus drawn of Galen as an anatomist and physician, one might infer that he should rank very high as a scientific exponent of medicine, even in comparison with modern physicians. There is, however, another side to the picture. His knowledge of anatomy was certainly very considerable, but many of his deductions and theories as to the functions of organs, the cause of diseases, and his methods of treating them, would be recognized as absurd by a modern school-boy of average intelligence. His greatness must be judged in comparison with ancient, not with modern, scientists. He maintained, for example, that respiration and the pulse-beat were for one and the same purpose--that of the reception of air into the arteries of the body. To him the act of breathing was for the purpose of admitting air into the lungs, whence it found its way into the heart, and from there was distributed throughout the body by means of the arteries. The skin also played an important part in supplying the body with air, the pores absorbing the air and distributing it through the arteries. But, as we know that he was aware of the fact that the arteries also contained blood, he must have believed that these vessels contained a mixture of the two. Modern anatomists know that the heart is divided into two approximately equal parts by an impermeable septum of tough fibres. Yet, Galen, who dissected the hearts of a vast number of the lower animals according to his own account, maintained that this septum was permeable, and that the air, entering one side of the heart from the lungs, passed through it into the opposite side and was then transferred to the arteries. He was equally at fault, although perhaps more excusably so, in his explanation of the action of the nerves. He had rightly pointed out that nerves were merely connections between the brain and spinal-cord and distant muscles and organs, and had recognized that there were two kinds of nerves, but his explanation of the action of these nerves was that "nervous spirits" were carried to the cavities of the brain by blood-vessels, and from there transmitted through the body along the nerve-trunks. In the human skull, overlying the nasal cavity, there are two thin plates of bone perforated with numerous small apertures. These apertures allow the passage of numerous nerve-filaments which extend from a group of cells in the brain to the delicate membranes in the nasal cavity. These perforations in the bone, therefore, are simply to allow the passage of the nerves. But Galen gave a very different explanation. He believed that impure "animal spirits" were carried to the cavities of the brain by the arteries in the neck and from there were sifted out through these perforated bones, and so expelled from the body. He had observed that the skin played an important part in cooling the body, but he seems to have believed that the heart was equally active in overheating it. The skin, therefore, absorbed air for the purpose of "cooling the heart," and this cooling process was aided by the brain, whose secretions aided also in the cooling process. The heart itself was the seat of courage; the brain the seat of the rational soul; and the liver the seat of love. The greatness of Galen's teachings lay in his knowledge of anatomy of the organs; his weakness was in his interpretations of their functions. Unfortunately, succeeding generations of physicians for something like a thousand years rejected the former but clung to the latter, so that the advances he had made were completely overshadowed by the mistakes of his teachings.