When was the rectal thermometer invented

Nowadays, the majority of adults use an oral or tympanic reading when taking their temperature. While mercury thermometers not the safest of choices are still in use here and there, digital thermometers have become much more widely accepted.

As technology has progressed, more options have become available that are quicker, more accurate, and less invasive. For example, the Withings connected thermometer, Thermo , launched in , can take a highly-accurate temperature at the temporal artery using an array of 16 infrared sensors. So, the next time you start to feel a fever coming on, and pick up a thermometer, think about the four centuries of innovation that it took to bring you the convenience of a modern thermometer!

Florentine thermometers, Mercury thermometer: Photo by Da Sal on Flickr. Photo by Tess Watson on Flickr. Automatic temperature tracking via Thermo. Thermo With Thermo, a fast, effortless gesture yields the most precise temperature possible.

It was later realized that water also has this property, as do other fluids and metals such as mercury. As a result, there are now many different forms of thermometers which have been developed over a period of several hundred years.

These simple instruments were constructed so as to trap air in glass tubes with the open end of the tube submersed in a reservoir of water. These open thermometers were termed thermoscopes.

In , Galileo used wine instead of water and was one of the first to use an alcohol thermometer. It was, of course, found that when carrying such a device up a mountain to a different altitude that the level in the tube was affected by the changing atmospheric pressure. These devices illustrated changes in sensible heat, before the concept of temperature had been recognized.

While it is sometimes claimed that Galileo was the inventor of the thermometer, what he actually produced was a thermoscope. He did discover that glass spheres filled with aqueous alcohol of different densities would rise and fall with changing temperature. Today, this is the principle of the Galilean thermometer, which is calibrated with a temperature scale.

The first illustration of a thermoscope showing a scale, which therefore can be described as a thermometer, was by Robert Fludd in However, around , Santorio Santorio calibrated the tube and went on to attempt to measure human temperature with his thermoscope. At the end of the sealed tube, he had a bulb blown of the optimal size to be inserted in the mouth. The open end was submersed in fluid.

As the air expanded due to the oral temperature, fluid was expelled from the tube. After a fixed period of time, the bulb was removed, the air cooled, causing the fluid to rise in the calibrated tube Fig.

A typical design of a thermoscope is a tube in which a liquid rises and falls as the temperature changes. The Sanctorius thermoscope.

This was the first thermometer to depend on the expansion and contraction of a liquid, which was independent of barometric pressure.

Many variants of this concept appeared, each unique as there was no standard scale. Christian Huygens in suggested using the melting point of ice and the boiling point of water as standards. There was still uncertainty about how well these parameters would work at different geographical latitudes.

In , Carlo Renaldini suggested that the ice and boiling water limits should be adopted as a universal scale. In , a German instrument-maker named Gabriel Fahrenheit produced a temperature scale that now bears his name.

He manufactured high-quality thermometers with mercury which has a high coefficient of expansion with an inscribed scale with greater reproducibility. It was this that led to their general adoption. Fahrenheit first calibrated his thermometer with ice and sea salt as zero. In Uppsala , Sweden, Anders Celsius — had been involved in meteorological observations as an astronomy student.

There were at that time a large number of different thermometers, all with different scales. He may have already at that early stage in his career realized that there was a need for a common international scale. He was appointed as professor of astronomy at Uppsala as his father had been before him and was involved in meteorological surveys.

Celsius was the first to perform and publish careful experiments leading to the establishment of an international temperature scale based on scientific data. He was for many years secretary of the Royal Society of Sciences at Uppsala. He also determined the dependence of boiling water on atmospheric pressure and gave a rule for the determination of the boiling point if the barometric pressure deviates from a standard pressure [ 3 ].

Why would a student of astronomy be interested in scales of temperature measurement? The position of zero was much discussed. Celsius had also used a thermometer created by the French astronomer Joseph-Nicolas Delisle with zero at the boiling point, thus giving a reversed scale with increasing numbers for decreasing temperatures, which avoided having negative values.

Various names are associated with this change. No single person was given credit. Celsius is now internationally recognized for his major contribution through his careful experiments and in using fixed points for calibration.

Imagine the setting for scientific discussions and the dissemination of new knowledge at the time of Linnaeus and Celsius. In Scotland in , Lord Kelvin realized in his study of heat that a much greater range of temperature could be considered, far beyond the centigrade scale.

Absolute zero, the level at which all molecular motion stops, gives the lowest conceivable temperature that can be found. Therefore, the lowest temperature on the Kelvin scale is 0, and the units are the same as the centigrade Celsius scale. While this scale is not used in clinical medicine, it may sometimes be used to define a temperature calibration source or similar scientific system. Thomas Seebeck, who was born in Estonia in , is the person most closely associated with the thermocouple as a temperature-measuring device.

In , when at the Berlin Academy of Sciences, he had studied the magnetic influence of an electrical current. A year later, he announced his discovery that two different metals forming a closed circuit will display magnetic properties when there is a difference of temperature between the two points of contact.

This, the Seebeck effect, is the basis of all thermoelectricity and led to the development of thermocouples for contact temperature measurement. Their main applications generally fall outside the temperature range of the human body, but some patient-monitoring devices used in critical care employ thermocouples taped to the skin for continuous measurements over time.

Thermocouples and thermistors are also used in sealed catheters for internal body temperature measurements [ 4 ]. The first non-contact radiometer designed to measure body temperature in the inner ear canal was invented in by Theodor Benzinger. When doing research on human temperature regulation at the US Naval Medical Research Institute in Bethesda, Benzinger developed a small radiometer to measure as close as possible to the brain.

This was intended to be a non-invasive procedure, to avoid attaching electrodes to the hypothalamus [ 5 ]. The first systems were produced in the United States, Europe, and Japan in the early s and have been increasingly adopted as a routine instrument for clinical thermometry Fig.

Measurement of body temperature in the ear canal. Since the earliest days of medicine, physicians have recognized that the human body can exhibit an abnormal rise in temperature, usually defined as fever, as an obvious symptom of certain illnesses. Physicians were aware of the use of their hand as a standard means for estimating temperature.

Hippocrates noted that the temperature of the body was important and insisted that physicians should be able to recognize the signs of abnormal temperature.

He taught that steps should be taken to raise the temperature where it is depressed and lower it when raised. Galen AD — described fever as calor praeter naturam or preternatural heat. As already noted, the first attempts to measure the temperature of a human body seem to have occurred in the sixteenth and seventeenth centuries and then first in Italy.

Giovanni Borelli, who had the support of Queen Christina of Sweden, was a pioneer of biomechanics and studied movement in animals. He is reputed to have tried many different measurements of the inner organs of live animals long before anaesthetics were available [ 6 ]. Santorio Santorio made an elaborate form of oral thermoscope to study human body temperature, although probably only with limited success.

Van Swieten became a professor of medicine at the University of Vienna and recommended that fever should be measured with a thermometer rather than with the hand.

He applied the mercury thermometer to both the mouth and axilla as recommended by Fahrenheit. Anton de Haen taught clinical practice at the Vienna General Hospital and emphasized to all his students of the importance of measuring body temperature in fever. Unfortunately, his studies were scattered throughout his 15 volumes of publications, Ratio Medendi — Post number 1.

Post number 2. Post number 3. I now, Butt what year and country? Post number 4. I got you started. There was probably simultaneous inventions in a few places. Google your questions. Make believe you are in college.