DR. DRAPER'S SCIENTIFIC MEMOIRS.* Is this country, the name of
Dr. Draper became famous in one hour. To some scientific workers, he had been already known as one who was patient in work, skilful in devising and carrying out experiments, and who had made considerable additions to our knowledge. Some people had read his Intellectual Develop- ment of Europe, without being much impressed either by its accuracy or its depth. But the celebrated Belfast address of Professor Tyndall, and the thoroughness of his expressed trust in the accuracy and ability of Dr. Draper, sent many people with a rash to the perusal of his works. The Intellectual Development of Europe had a sudden increase of readers. And when the Conflict of Religion and Science was shortly after published, many were prepared to give it a hearty welcome. But to most people, the perusal of these works was a demonstra- tion, not of the competency of Dr. Draper as a guide through the mazes of history, philosophy, and religion, but of the fact that Professor Tyndall was a man of great faith ; and they re- joiced to find that the most rigid adherence to the severity of the scientific method was not incompatible, in the case of the
Scientific Memoirs. being Experimental Contributions to a Knowledge of Radiant Energy. By John William Draper, 1LD., LL.D. London: Sampson Low and Co.
brilliant Professor, with the sublime simplicity of a child-like trust. It was unfortunate, however, for the reputation of Dr. Draper that the-great eulogium of Professor Tyndall was pro- nounced, not on his scientific, but on his literaryworks. -For; as these Memoirs show, Dr. Draper has been for many years-a,
careful, diligent, and successful worker in the physical depart- ments of science, and has, without question, extended the boundaries of our scientific knowledge. Had his Claim to eminence been based on these Memoirs, or on work done in this department, it would have been at once admitted;
and his name would have occupied, as, in fact, it does occupy, an honoured place among the names of those who have widened the horizon of our knowledge. His fame as a man of science is secure, but his place as a philosopher and as a historian rests on
a very precarious foundation.
These Memoirs are records of experiments and observations in the domain of radiant energy, and first appeared in American scientific journals. They are greatly condensed, and in fact are now published in order to vindicate the claim of the author to be one of the earliest contributors to our present knowledge of radiant energy. It is right that Dr. Draper should place these achievements of his on record, as many either did not know or ignored his claim, and text-books in science have hitherto attributed to others observations and experiments which he was the first to publish. At the time when Dr. Draper began his scientific experiments, the spectro- scope was comparatively new, and its possibilities as an in- strument of research were not yet ascertained. In the very first of these Memoirs, Dr. Draper made a very momentous dis- covery. The object he had in view was to ascertain at what temperature bodies became self-luminous, and he found that all solid bodies begin to give out light at the same temperature. Next, he desired to determine the relation of the temperature of a solid body to the colour of the light it gives forth. Here it was necessary to have a fixed standard of comparison, and he found, to his surprise, that there are no fixed lines in the light of incandescence, such as are in the sunshine and daylight. Here he came across one of the most important and fruitful discoveries of recent times. The Fraunhofer lines are not to be seen in the spectrum of ignited solid bodies. The spectrum of an incandescent solid is continuous, while the spec- trum of an ignited gas is discontinuous, and is broken up by lines or bands. This was published in 1847, thirteen years before Professor Kirchoff had published any of his discoveries. It does not appear from these condensed Memoirs that Dr. Draper was aware of the great significance of the fact he had observed, and of the sudden extension of our knowledge, which arose when its meaning was understood. For this fact has furnished to men of science a sure means of determining the physical conditions of the heavenly bodies, and by it the rays of light which reach our earth are made to tell the story of their birth, and the physical state of the body from which they came. Without doubt, to Dr. Draper is due the first observation of the continuousness of the spectrum of an ignited solid body, and henceforth the text-books ought to acknowledge his claim to priority of observation.
Light is made to disclose to science the state of the body from whence it came. Another subject of inquiry of great interest and importance is its effect on the bodies on which it falls. In this also Dr. Draper has done effective service. He affirms the effect to depend on the quality of the substance on which a ray of light falls :—
"The vibrations imparted to it may be manifested by the produc- tion of heat, as in the case of lamp-black, or by chemical changes, as in the case of many of the salts of silver. In the parallel ease of acoustics, clear views have long ago been attained, and are firmly held. No one supposes that sound is one of the ingredients of the atmo- sphere, and it would not be more incorrect to assert that it is some- thing emitted by the surrounding body, than it is to affirm that light, or heat, or actinism is emitted by the sun." (p. 402.)
The production of heat arises from the stoppage of ether-waves. It is a pure instance of the conversion of motion into heat, an illustration of the conservation and transmutation of force ; and the allocation of heat, light, and chemical action to sepa- rate parts of the spectrum, is not borne out by the experiment of Dr. Draper. Here also Dr. Draper has been singularly suc- cessful, and his work is a distinct gain to science.
We do not enter at further length into these scientific memoirs. We find ourselves irresistibly attracted by the pre- face, in which Dr. Draper gives us an account of his scientific, historical, and literary labours. We turned to this preface to find an explanation of the strange phenomenon that a man so capable as Dr. Draper, should have written works of the stamp the History of the Intellectual Development of Europe and the Conflict between, Religion and Science. Nor did we seek in vain. For after describing the various tasks he undertook, and the way in which he was led to undertake them, he naively adds : —" When I thus look back on the objects that have occupied my attention, I recognise how they have been interconnected, each preparing the way for its successor. Is it not true that for every person the course of life is along the line of least resistance, and that in this the movement of humanity is like the movement of material bodies ? " This remark re- called to our recollection a sentence in the Conflict between, Religion and Science :—" The scientific philosopher affirms that the condition of the world at any given moment is the direct result of its condition in the preceding moment, and the direct cause of its condition in the subsequent moment. Law and chance are only different names for mechanical necessity." (pp. 229-30.) Movement along the line of least resistance is, indeed, a matter of mechanical necessity, and will sufficiently explain the result, when the conditions of the problem are only me- chanical. When the conditions grow more complex, what then ? Is it not possible so to simplify the problem as to leave out what is most necessary to be explained? This seems to us to be the mistake into which most physicists fall, whenever they make in- cursions into the domain of chemistry, of physiology, and most specially when they rash into the domain of human history and human life. They see that mechanical laws and mechanical causes have their part to play everywhere. When we ascend from the problems set us by matter and motion considered simply in themselves to the more complex problems of chem- istry, we carry with us, as essential helps to their solution, all that we have come to know regarding statics and dynamics, and the laws of motion and inertia. And in physiology we have the results of mechanical and chemical science, as data to enable us to grapple with the higher problems of organic life. And again, in the most complex questions of personal intelligence and of moral life, in the individual and in the social organism, we do not lose sight of the knowledge we have won in the simpler sciences. The problems set by natural philosophy are the simplest of all ; and fascinated by the sim- plicity and power of their method, when applied to questions of conditions comparatively simple, men like Dr. Draper have applied the same method to the problems of human history, and in order to make the method applicable, they have first eliminated everything save mechanical necessity. It is certainly the line of least resistance, to reduce the whole phenomena of history to the simple condition of mechanical necessity. The line of least resistance for a ship is to drift with wind and tide, but there -often happens to be another kind of force on board, which by tact and skill bends the mechanical to its own purpose, and in -spite of wind and tide safely brings her into the harbour. What would we say of a science which would explain the voyage of a ship from shore to shore, by showing that at each moment her course was determined by purely mechanical laws? No doubt the -propelling force, the displacement of water, the action and re- action of wind and wave, are all purely mechanical ; but while this is unquestionably true, the guiding purpose of cap- tain and of crew is the one sufficient explanation of the destination of the ship. Mechanical laws are ever amenable to higher forces. They are ever active ; but whether to this result or to that, is to them a matter of indifference. The law of the diffusion of gases obtains within the lungs of living creatures, as elsewhere, and the laws of fluid action have as much to do with the circulation of the blood as they have to do with the water-supply of our large cities ; but the mechanical-neces- sity hypothesis will no more explain the living organism, than it will explain the existence and distribution of gas and water- pipes in the City of London. Unless there were fixed and un- changeable mechanical laws, there could neither be living organism nor water-supply, but to say that mechanical neces- sity can account for either, seems to be utterly contrary to the most elementary principles of human belief.
It would be well if our men of science were to remember that in dealing with physiological questions, there are elements to
be taken into account which by no means appear in problems of heat and light, and the like ; and new elements are ever added as we ascend the scale,—and the problems of history are the most complex of all. So complex are these problems, that our 'est conclusions are only approximations. Political economy
has simplified its problems, by looking on man as a creature with wants which are to be supplied ; and all its conclusions have direct relation to that end. But man has wider relations and can be looked at in other aspects than those contemplated by political economy, and so when motives of self-sacrifice—pity compassion, and other motives of the disinterested kind—enter in, political economy finds its conclusions inadequate. The writer of history must, therefore, take into account all the forces, physical, hereditary, moral, social, and religious, which move men, and the special aspects of these which are dominant at any period ; and it is evident that here there is a much more difficult task in hand than to determine the influence of light upon chlorine, or the distribution of sap in plants. Dr. Draper has written history on the same principles and with the same method as he applied to the physical sciences, and it is no wonder that by that method he came to the results we know Mechanical necessity has its due place in the explanation o history, but there are other and more important forces in history than mechanical necessity, and these are precisely those which Dr. Draper and his school have not recognised. While, there- fore, we give all praise to Dr. Draper for the skilful and suc- cessful work he has done in the domain of physical science, we say of the books he mentions in his preface, and which he tells us have been translated into most European languages, that in them he has misconceived the conditions of his problem, writing of men and nations as if they were forces and molecules, and as if the drift of mechanical forces were adequate to explain the progress of events in history.
Previous page
