Sesquicentennial of the Clinical Thermometer

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The history of the thermometer is studded with famous and familiar names. Galileo Galilei from Pisa, Santorio from Padua, and Huygens from The Hague developed temperature measuring devices, and Celsius from Uppsala, a Swede with a latinized name, Fahrenheit, from the Hanseatic city of Danzig, now in Poland, René Antoine Ferchault de Réaumur, a Frenchman, and Lord Kelvin, an Irish scientist from Belfast made improvement to the device, its composition, its usability, range and scale. This was a truly Pan-European scientific effort, it seems, long before there was anything like a European Union.

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Sir TC Allbutt – source: Wikipedia

As infectious diseases doctors we are – to a large degree – ‘fever doctors’, hence we would like to add Sir Thomas Clifford Allbutt to our honor list. He is the little known inventor of the first clinically useful thermometer, the predecessor of the now old-fashioned mercury thermometer. We want to celebrate the sesquicentennial of his 1866 improvement of what used to be a very clumsy device.

The Encyclopedia Britannica states that Allbutt “introduced the modern clinical thermometer, a welcome alternative to the foot-long instrument that required 20 minutes to register a patient’s temperature.[1] Indeed, Allbutt’s thermometer was a 6 inch portable instrument which gave reliable readings in 5 minutes, and which looks very familiar and modern (see below) [2].  

Before the advent of the Allbutt thermometer, instruments available to clinicians for temperature measurement were clumsy and unwieldy. Descriptions of foot-long thermometers were common. Then came the Aitken thermometer, a mercury containing smaller device which was introduced in 1852. Despite an improved design it was still not convenient to use; Dr. Savage, a house officer in Edinburgh at the time,  tells us how he had to carry it around under his arm in a case ‘like a gun’ and how much a difference the new Allbutt thermometer made.[3]

As so often, advances in technology spearheaded medical progress.

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Prof. Carl Wunderlich – source: Wikipedia

Nonetheless, the groundwork for measuring temperature was laid with the old foot-long instrument. It was Prof. Carl Wunderlich, a German doctor from Leipzig, who was asked by Traube, another famous name in the history of German medicine, to devote himself to temperature studies. Starting in 1851, he collected millions of temperature recordings from over 25,000 patients. His studies established the normal range for body temperature which we still use today and the 98.6 oF cut-off for fever. He proudly reported that over 17 years there has been no patient on the ward of his hospital that did not have regular temperature measurements [4].

Wunderlich describes the periodic fever of malaria and the continuous fever of typhoid.

Carl August Wunderlich’s book is available online in its entirety [5]. It is a remarkably complete publication addressing many aspects of body temperature generation, regulation, and fluctuations in health and disease. It contains a chapter on thermometry, the instruments available and preferred, their proper use, the sources of error, technological issues and calibration needs, internal controls, placement of the thermometer, the benefits of repeat monitoring and of documenting a temperature curve. He describes the amazing stability of body temperatures under various environmental conditions, the small diurnal variations (normally 0.5 oC higher in the afternoon than in the morning), the normal temperature range in pregnancy, newborns, elderly, the influence of race, sex, climactic factors.

Regarding the influence of activity, he mentions that physical exercise is affecting body temperature, but mental exercise is not. CARL A WUNDERLICH

 The benefit of ice compresses to lower body temperature is described. It is impossible to describe the myriad of details he checked and considered.

The importance of the topic is concisely summarized in the book’s introduction which I am providing here in abridged form:

“Knowledge of patient body temperature is important and imperative for the physician because:

  • Every property of the sick body is worth knowing about
  • It can be measured very accurately
  • A deviation from the normal range directly indicates a disorder, or febrile disease if beyond a threshold
  • The degree of fever often is related to disease severity
  • The temperature curve can give indication of the course of disease
  • It can show response to therapeutic interventions
  • Deviations in temperature curves from the normal course can provide early warnings
  • It can indicate the stage of disease and the beginning of convalescence”

There is a lot more in this encyclopedic description of temperature and fever. We owe a lot to the work of Allbutt and Wunderlich. Reading the old passages on temperature and how it became a vital sign, this sesquicentennial all of a sudden feels very relevant and fresh.

[2] J Pearce. Historical Note: A brief history of the clinical thermometer. Q J Med 2002, 95:251
[3] G Savage. On the use of the clinical thermometer. Letter to the Editor. Lancet 1916; p. 317
[4] C Wunderlich. Das Verhalten der Eigenwärme in Krankheiten. Verlag Otto Wigand, Leipzig, 1870. p.52
[5] Accessed May 2016:

The Thackray Museum in Leeds has this Allbutt thermometer on display:


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