Excerpted from Roy Porter, "Clinical Science," in Roy Porter, ed., Cambridge Illustrated History of Medicine (1996), 173-177.

Shortly after 180O, medical science was revolutionized by a clutch of French professors, whose work was shaped by the opportunities created by the French Revolution for physicians to use big public hospitals for research. Among physicians, they acquired a heroic status, not unlike Napoleon himself. Perhaps the most distinguished was René-Theophilé-Hyacinthe Laënnec, a pupil of François Bichat. In 1814, he became physician to the Salpêtrière Hospital and two years later chief physician to the Hôpital Necker. In 1816, Laënnec invented the stethoscope. Here is how he described his discovery:

• In 1816 I was consulted by a young woman presenting general symptoms of disease of the heart. Owing to her stoutness little information could be gathered by application of the hand and percussion. The patient's age and sex did not permit me to resort to the kind of examination I have just described (direct application of the ear to the chest). I recalled a well-known acoustic phenomenon: namely, if you place your ear against one end of a wooden beam the scratch of a pin at the other extremity is distinctly audible. It occurred to me that this physical property might serve a useful purpose in the case with which I was then dealing. Taking a sheet of paper I rolled it into a very tight roll, one end of which I placed on the precordial region, whilst I put my ear to the other. I was both surprisedand gratified at being able to hear the beating of the heart with much greater clearness and distinctness than I had ever before by direct application of my ear. I saw at once that this means might become a useful method for studying, notonly the beating of the heart, but likewise all movements capable of producing sound in the thoracic vacity, and that consequently it might serve for the investigation of respiration, the voice, rales and possibly even the movements of liquid effused into the pleural cavity or pericardium.

On the basis of his knowledge of the different normal and abnormal breath sounds, Laënnec diagnosed a multiplicity of pulmonary ailments: bronchitis, pneumonia, and, above all, pulmonary tuberculosis (phthisis or consumption). His outstanding publication, Traité de l'Auscultation médiate (1819), included clinical and pathological descriptions of many chest diseases. Ironically, Laënnec himself died of tuberculosis.

Laënnec's investigations paralleled those of his colleague, Gaspard Laurent Bayle, who in 1810 published a classic monograph on phthisis, on the basis of more than 900 dissections. Bayle's outlook was different from Laënnec's. He was more interested in taxonomy, and distinguished six distinct types of pulmonary phthisis. Laënnec had no interest in classification; rather, his ability to hear and interpret breath sounds made him primarily interested in the course of the diseases he examined. Like other contemporary French hospital physicians, he was accused of showing greater concern for diagnosis than for therapy - but this stemmed not from indifference to the sick but from a deep awareness of therapeutic limitations. Translations of Laënnec's book spread the technique of stethoscopy, as did the foreign students drawn to Paris. A man with a stethoscope draped round his neck became the prime nineteenth-century image of medicine: the instrument had the word science written on it.

Laënnec remains the one famous name amongst the generation of post-1800 French physicians who insisted that medicine must become a science and who believed that scientific diagnosis formed its pith and marrow. At the time, however, the most illustrious was Pierre Louis, whose writings set out the key agenda of the new 'hospital medicine'. Graduating in Paris in 1813, Louis spent seven years practicing in Russia. On returning home, he plunged into the wards of the Pitié hospital and published the results of his experiences in a massive book on tuberculosis (1825), followed 4 years later by another on fever.

Louis was, furthermore, a passionate advocate of numerical methods - the culmination of an outlook that had begun in the Enlightenment. Louis' mathematics were little more than simple arithmetic - quantitative categorizations of symptoms, lesions, and diseases, and (most significantly) application of numerical methods to test his therapies. To some degree, Louis sought to use medical arithmetic to discredit existing therapeutic practices: he was thus a pioneer of clinical trials. Only through the collection of myriad instances, he stressed, could doctors hope to formulate general laws.

The 'Paris school' was not a single cohesive philosophy of medical investigation. Nevertheless, there was something distinguished about Paris medicine; and during the first half of the nineteenth century students from Europe and North America flocked to France. Young men who studied in Paris returned home to fly the flag for French medicine. Disciples in London, Geneva, Vienna, Philadelphia, Dublin, and Edinburgh followed the French in emphasizing physical diagnosis and pathological correlation. They often also took back with them knowledge and skills in basic sciences such as chemistry and microscopy. Several leading English stethoscopists, including Thomas Hodgkin (of Hodgkin's disease), learned the technique directly from Laënnec himself.

Imitating the French example, medical education everywhere grew more systematic, more scientific. Stimulated by teachers who had studied in Paris, medical teaching in London expanded: by 1841, St George's Hospital had 200 pupils, St Bartholomew's 300. There were hundreds of students in other London hospital
schools as well, and from the 1830s London also boasted a teaching university, with two colleges, University and King's, each with medical faculties and purpose-built hospitals.

London become a major centre of scientific medicine. Amongst the most eminent investigators was Thomas Addison, who became the leading medical teacher and diagnostician at Guy's Hospital where he collaborated with Richard Bright and identified Addison's disease (insufficiency of the suprarenal capsules) and Addison's anaemia (pernicious anaemia). Bright for his part was a member of the staff et Guy's Hospital from 1820. His Reports of Medical Cases (1827-31) contain his description of kidney disease (Bright's disease), with its associated dropsy and protein in the urine.

Vienna also grew in eminence. The University of Vienna had well- established traditions: the old medical school had bedside teaching on the model espoused by Herman Boerhaave in the early eighteenth century, but decay had set in towards 1800. However, new teaching was introduced by the Paris-inspired Carl von Rokitanski, who made pathological anatomy compulsory. The age's most obsessive dissector (supposedly performing some 60,000 autopsies in all), Rokitanski had a superb mastery of anatomy and pathological science, and left notable studies of congenital malformations and reports of numerous conditions, including pneumonia, peptic ulcer, and valvular heart disease.

In the USA, by contrast, high-quality medical schools and clinical investigations developed more slowly. In its laissez faire, business-dominated atmosphere, many schools were blatantly commercial, inadequately staffed, and offered cut price degrees.