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BRITISH AND FOREIGN

1. On the Use of the Sphygmograph in the Investigation of Dis-
ease. By BALTHAZAR W. FOSTER, M.D., &c. London:
Churchill and Sons. 1866. Pp. 42.

2. On the Application of the Graphical Method to the Study of

Diseases of the Heart and Great Vessels. By BALTHAZAR W.

FOSTER, M.D., &c. Medical Times and Gazette,' vol. ii,

1866; vol. i, 1867.

3. On the Application of Physical Methods to the Exploration
of the Movements of the Heart and Pulse in Disease. By T.
BURDON SANDERSON, M.D., and FRANCIS E. ANSTIE, M.D.
'Lancet,' vol. ii, 1866, and vol. i, 1867.

4. Sphygmographic Observations on the Pulse of Typhus. By
THOMAS WRIGLEY GRIMSHAW, A.B., M.B. Dubla Quar-
terly Journal of Medical Science,' February, 1867.

5. Note on the Regulation of the Pressure on the Artery in the

Application of the Sphygmograph. By BALTHAZAR W.

FOSTER, M.D. 'British and Foreign Medico-Chirurgical

Review,' July, 1867.

6. Lectures on the Prognosis and Treatment of Certain Acute
Diseases, with special reference to the indications afforded by
the graphic study of the Pulse. Delivered at the Royal
College of Physicians of London. By FRANCIS E. ANSTIE,
Lancet,' vol. ii, 1867.

M.D., &c.

83-XLII.

1

7. Handbook of the Sphygmograph: being a Guide to its Use in Clinical Research. To which is appended a Lecture delivered at the Royal College of Physicians on the 29th March, 1867, on the Mode and Duration of the Contraction of the Heart in Health and Disease. By J. BURDON SANDERSON, M.D., &c. London: Hardwicke. 1867. Pp. 83.

8. On a New Method of Increasing the Pressure on the Artery in the Use of the Sphygmograph. By BALTHAZAR W. FOSTER, M.D., &c. The Journal of Anatomy and Physiology,' November, 1867.

IN glancing at the past history of medicine, the observer cannot fail to be struck with the extremely slow advance made during the earlier stages of its scientific growth. Science after science, born later, has reached a comparative maturity more quickly, and this, too, in spite of the fact that medicine has ever had its special votaries. So slow has been the progress that every now and then some impatient spirit asserts that medicine can never attain a scientific form. A little careful reflection leads to an explanation of this tardy evolution; for through the whole range of human knowledge there runs one invariable law of growth which determines the advance from the more simple to the more complex. Hence we see that those sciences which deal with the succession and relation of the more simple phænomena of nature, have been the first to assume a scientific form; for the method required to analyse their less complicated problems has been more easily acquired. The relatively high degree of perfection which astronomy has attained, and the rapid growth of geology, notwithstanding the late period at which its development began, seem almost discouraging to the investigator of biological phenomena when contrasted with the slow advance of his own study. A little closer scrutiny, however, reminds us that the phænomena with which such sciences as astronomy and geology are occupied are much less complicated with phenomena of a different kind than those of biology.

Observation alone has sufficed to penetrate into their more simple secrets; hence such sciences have been well called sciences of observation. On the contrary, when we come to consider medicine in relation to the other sciences, we cannot fail to mark the increased complexity of the questions with which it has to deal, questions requiring for their solution not only a knowledge of the laws which rule the phænomena of healthy life, but also those which regulate diseased action. Medicine in its true sense is a triad of sciences, of which two partsphysiology and pathology-are only partially developed, and the

third-therapeutics-can only approach a scientific form, when the two former are more matured. Yet the three component parts exist together, each reacting upon the other, the more complex often aiding the development of the more simple. But in addition to the complexity of its phænomena, a complexity so great as to require all the other sciences to be impressed as auxiliaries, we can find another explanation of slow progress in the inefficiency of the method formerly applied. Medicine when first cultivated could only be approached by the method of observation, which, while it achieved vast conquests in the region of the simpler sciences, advanced but little the evolution of medicine.

Bernard has well shown that medicine could never arrive at any high development as a science of observation, for such sciences in their maturity lead simply to a knowledge of the invariable laws which regulate the succession and relation of phænomena, but give no power of modifying this relation and succession at will. Medicine entered on this stage of its growth long since, and has given the physician a certain amount of prevision with regard to disease, but little power of modifying its course. The empiricists of old were ever struggling against this tendency of medicine to become a mere science of observation, and in their rude way were pointing out what a later age has taught us, that only by employing experiment in addition to observation can medicine attain its highest development. To the recognition of the value of experiment in physiological research do we owe the great discoveries of modern times, and in chemistry we see the most brilliant results of the experimental method. Experiment is, however, only an extension of observation, by means of which the investigator repeatedly studies phænomena under known conditions, in order that he may render his analysis of their relation and succession more perfect. The observer studies phænomena which he cannot control in order to discover the laws which they obey. The experimenter modifies at will the conditions under which phænomena exist, and thus gains a deeper insight into their nature. In both cases it is of the greatest importance to render more precise the investigator's power of recognising the finer shades of resemblance and difference between phænomena, for in proportion to this precision will be the value of his results. Every means, then, which renders our observation of phænomena more exact gives an impulse to science. So intimate is this relation between instrumental aid and progress, that the position of a science might almost be inferred from the extent of its apparatus. How great a part the telescope has played in the advance of astronomy, how rapid has been the growth of our knowledge of the structure of the tissues since the invention of the microscope, must

be familiarly known to every reader. More recently the inven tion of the spectroscope has given to chemistry a new vitality, and directed the energy of observers into fresh channels. Indeed, throughout the history of physics and chemistry the great landmarks of progress correspond to the invention of new instrumental contrivances to supplement the powers of the investigator.

Physiology bears witness also in almost every step of its recent advance to the great utility of improved instrumental aid. We may especially refer on this point to the recent work of Marey, 'Du mouvement dans les fonctions de la vie,' which tells us in every page how the accuracy of the experiments of the physiologist has been increased by mechanical contrivances. Medicine has not been ignorant of the benefits derived from this striking feature of modern science, for its most brilliant achievements have been made by the increased power of accurate observation which the microscope has given to the pathologist, the stethoscope to the physician. The laryngoscope, the endoscope, and the ophthalmoscope, have also added to our knowledge, and the last promises to quicken to a still greater degree than it has hitherto done, our insight into the morbid conditions of the deeper nervous structures. The thermometer has given a precision to our estimate of the essential phænomena of fever, and thus increased the accuracy of our diagnosis and our certainty of prognosis. To enumerate all the mechanical means which have advanced modern science would occupy too much of our space; we have already said enough to show how great has been their influence for good in our own special branch of study. Every fresh invention has given us, as it were, a new sense wherewith to attack more successfully the great problems which have hitherto defied our analysis.

The instrument which forms the subject of the present article has in this way contributed largely to our knowledge of the phænomena of the circulation. The finer features of arterial pulsation which escaped recognition by our mere sense of touch have been elucidated by its aid. What appeared to our fingers as a single or occasionally a double beat has been broken up into its component parts, and these parts have been gradually recog nised in their true relation to other and antecedent phænomena. But, as we shall see, this development of physiological knowledge has stimulated our observation of disease, and given an accuracy to our power of distinguishing various forms of pulse never before generally attained. Once or twice in a century the tactus eruditus of a great master gave him a wonderful power in discriminating the various peculiarities of pulse movement, but the imperfection of the knowledge was shown by the impossibility of communicating it. The sensation perceived

was too vague to be conveyed to the mind of another, and thus the exceptional knowledge was of little use to science. But now the sphygmograph enables the student to refer his sensation of a pulse-beat to a visible representation of the pulse movement, and thus promises to dispel that vagueness in the description of the same phænomena which is caused by the varying delicacy of the sense of touch.

Students need no longer crowd round the bedside, anxious but unable to perceive those finer features of the pulse to which their teacher refers, for in future the tracing of the pulsation will tell them, in unmistakeable language, the delicate shades of movement which scarcely any finger can appreciate, and still fewer physicians describe. That the invention of the sphygmograph has already led to a much more exact knowledge of the circulation, none will dispute; and, indeed, there can be little doubt that it is also destined to render great services in the hands of the physician. The few industrious investigators who have applied it to purposes of clinical research in this country have shown that it is capable of extended usefulness; and in the following pages we propose to consider the results which their publications placed at the head of this article contain. In so doing we shall first present our readers with a brief exposition of the recent advances of our knowledge of the healthy pulse curve, and then, after alluding to the suggested modifications in the form and application of the instrument, we shall proceed to discuss its importance as an aid in the study of disease.

Marey, in his admirable work, 'Physiologie Médicale de la Circulation du Sang,' did not notice some of the peculiarities of the pulse curve, which have since been shown to be of high importance, and consequently those who followed Marey's views too exclusively fell into the same error. Thus, in the earlier papers, the pulse-curve recorded by the sphygmograph was described as consisting of a line of ascension, a summit, and a line of descension, the last being broken normally by the occurrence of a large undulation, which was called the dicrotism or second beat. The forms of these several parts of the curve were stated to undergo considerable modification in physiological conditions, and still greater changes were referred to the existence of disease. The line of descension, the most important part of the curve, was soon noticed to vary very much in the number of its undulations: and the occurrence of several of these, instead of the single undulation or dicrotism, which observers had been taught to look for, suggested to some minds a doubt of the accuracy of the record. The sphygmograph was accused of untruthfulness, and the additional undulations were referred to acquired vibrations of the writing lever, totally independent of the pulse move

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