In the year 1816 a French physician, Rene Theophile Hyacinthe Laennec, achieved undying fame by publishing to the world an account of his labors in the application of mediate auscultation and of percussion to the diagnosis of the diseases of the chest.  It is true that no less a personage than the “Father of Medicine,” Hippocrates, is reputed to have practised succussion as a means of diagnosis; that is, the shaking of a patient, as one would shake a cask, to ascertain by the occurrence or non-occurrence of a splashing sound if the person’s pleural cavity was distended partly with water and partly with air.  It is probable that Hippocrates and many others after him carried the physical examination of the chest still further, for it is difficult to imagine, for example, that so simple a device as that of thumping a partition to make out the situation of a joist by the sound evoked should not early have been applied to the human chest.  But, be this as it may, to Laennec belongs the great credit of having laid a substantial foundation for the physical diagnosis of the present time, and, more than for laying a foundation, for constructing a fairly complete edifice.  He who should now undertake to practise general medicine without having first made himself proficient in the detection and interpretation of the sounds elicited by auscultation and percussion in diseases of the heart and lungs would foredoom himself to failure.

It was not until many years later, early in the second half of the century, that the clinical thermometer came into general use, but it soon showed most strikingly the superiority of the “instrument of precision” to the unaided senses of man.  Who would think now of trying to estimate the height of a fever by laying his hand on the patient’s skin, or who, even among the laity, would be satisfied with such a procedure?  “Doubtless,” said the present writer in a former publication ("New York Medical Journal,” Dec. 29, 1900), “the use of the thermometer has occasionally given rise to needless alarm, but almost invariably it may be interpreted with great certainty.  Often it dispels unnecessary anxiety as in a twinkling by its negative indication, and surely it is to be credited with being distinctly diagnostic in those diseases of which it has itself established the ‘curve.’” By the thermometric “curve” of a disease is understood the general visual impression made by the graphic chart of a temperature record—­the course of a zigzag line connecting the points indicated by the various individual observations.

Numerous other instruments of precision are now in constant use, among the most wonderful of which perhaps is the ophthalmoscope, whereby we are enabled to subject the retina and the intervening media of the eye to minute visual examination.  There is not an organ of the body that is not now interrogated daily in the way of physical diagnosis, and we even examine separately the secretion of each of the two kidneys.