The system for measuring temperature on a decimal scale was introduced by Anders Celsius, a Swedish astronomer with many accomplishments in a short life. The Celsius scale was originally called the centigrade scale, from the Latin words centus for one hundred and gradus meaning degree. The eponym Celsius wasn’t adopted by the scientific community until 1948 and remains the only scientific symbol in the upper case (°C), to distinguish it from the lower case c (constant) famous from Einstein’s energy equation.

Despite his obvious genius, the centigrade scale originally proposed by Anders Celsius had 100 as the freezing point of water and 0 as the boiling point. In 1744 and shortly after his death, the great Swedish scientist Carl Linneaus reversed the scale making hot temperatures have higher numbers than cold temperatures.

Today the Celsius scale is the most widely used scale for measuring and reporting temperature. In addition to his interest in a better scale for measuring temperature, Anders Celsius participated in expeditions to confirm Isaac Newton’s theory that the Earth is not a perfect sphere but rather ellipsoid, and also was the first to use colored glass plates to try to analyse and catalog magnitude and differences in stars. He supported the formation of the Royal Swedish Academy of Sciences (along with Carl Linneaus and several others) and was elected to the Academy in its first meeting. He died of tuberculosis in 1744 at the age of 42.

Image of Anders Celsius from the portrait that hangs in his honor at the Uppsala Astronomical Observatory which he founded shortly before his death. Image in the public domain.

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Today is the birthday of English scientist Norman Lockyer, who both discovered (along with others) helium and named it. On August 18, 1868 several teams of scientists gathered along the path of a predicted total solar eclipse to utilize the recently discovered understanding of the emerging science of spectography. Gustave Kirchoff had theorized that the Fraunhofer lines in the solar spectrum corresponded to elements in the sun. French scientist Pierre Janssen and English scientist Norman Lockyer observed the eclipse independently and both proposed the presence of an unknown element which Lockyer named Helium. Lockyer used the Ancient Greek word helios meaning sun, anglicized to helium. It wasn’t discovered on earth for another 30 years.

Helium has a wide variety of scientific and industrial uses-it is used in cryogenics (its largest single use, absorbing about a quarter of production), for industrial uses—as a pressurizing and purge gas. A minor use is as a lifting gas in balloons and airships. 

 Image of the solar eclipse of August 1868 from Total Eclipses of the Sun by Mabel Loomis Todd.

On May 16, 1960, Theodore Harold Maiman operated the first laser, utilizing a synthetic ruby crystal grown by his colleague Dr. Ralph L. Hutcheson.  A race had been underway in the scientific community for more than a decade to develop such a device, starting first with masers before moving on to lasers.

The word LASER is an acronym (the first acronym to appear on this blog) and stands for light amplification by stimulated emmission of radiation.  When the laser (and maser-microwave amplification by stimulated emmission of radiation) was first developed it was know as a solution looking for a problem.  Scientists and engineers saw incredible potential for such a device, and now lasers are ubiquitous and range in size from smaller than the head of a pin to the size of football fields.  Lasers can be found in cd and dvd players, fingerprint readers, bar-code scanners, in medicine as a replacement for scalpels, in printers, dermatology, welding and cutting and even rock concerts and kids shows.  

Image of an early ruby laser Courtesy Lawrence Livermore National Laboratory.

Before Edward Jenner discovered and popularized vaccination, the technique of inoculation had long been in use around the world, with more or less success to combat small pox.  Doctors had known for centuries that a small and controlled exposure to the deadly virus variola could lead to immunity even if the mechanism was unknown.  What doctors and scientists did not know was that there were many strains of the variola virus, some much more deadly than others.  Inoculation worked by introducing controlled amounts of the virus into the system and allowing the body to develop natural antibodies to the virus.  Edward Jenner was finally able to show that the different variations of variola virus were similar enough that inoculating with a non-lethal version, in this case cowpox, was enough to grant immunity to the lethal forms.

The word inoculation came from the Latin word inoculatus, the past participle of inoculare meaning to graft in, implant, in the horticultural sense of buds on a tree or plant.  Inoculate combined the prefix in- and the Latin word oculus which could mean bud or sprout but originally meant eye.  It took its modern meaning  of implant germs to produce immunity from around the time Lady Montagu brought inoculation back from India around 1714, where she was stationed with her husband, the ambassador Edward Wortley Montagu.  Since the advent of vaccines, the word inoculation has been used synonymously with vaccination. 

Image of smallpox vaccination site courtesy Centers for Disease Control.

The word embryo comes into English in the mid 14th century fully formed from the Ancient Greek word embryon (εμβρυον) meaning a young one. In earlier Greek (specifically Homer) embryon meant a young animal and acquired the poetic use of fruit of the womb, a compound word composed of the prefix en and the root bryein (βρυειν) meaning to swell or be full.

Image of an embryo courtesy lunar caustic, used with permission under a creative commons 3.0 license.

Get ready for the 17 year cicada!    A fairly large insect of the order hemiptera, the cicada is known for the sound of its mating call, a shrill and monotonous buzz that can last for weeks at the end of summer.  Unlike crickets who make sounds by rubbing together body parts, cicadas produce their noise with a portion of their chitinous exoskeleton called the tymbal.

The word cicada comes from the Latin word cicada, and although it was common in  Latin it is considered a loan word from another language, but the loaner word and language is now lost.   The cicada enjoys world wide distribution with most varieties having a lifespan of 2-5 years, though some notably live much longer, specifically the 13 and 17 year cicadas.  Note the large wide set eyes-but also note the three smaller eyes in a triangular pattern between the larger eyes.

Image of a cicada emerging as imago from its last instar courtesy of Pete Lounsbury under a Creative Commons 3.0 license.

Today is the birthday of Henri Poincaré (29 April 1854 – 17 July 1912), French philosopher of science, engineer, mathematician, and theoretical physicist. Among his many contributions, Poincaré was the first to propose that nothing could travel faster than the speed of light in a vacuum. He also wrote a short paper on relativity that predated Einstein’s by several months-although Poincaré is rarely credited popularly with contributions to relativity, Einstein himself acknowledged his debt. Poincaré’s assertion that nothing is faster than light in a vacuum came at time when science was trying to establish what a vacuum meant at all-whether or not there was a measurable ether.

The word vacuum came into English in the 1540s from the neuter noun use of the Latin vacuus meaning empty.

Another shout out needed here: Poincaré taught at L’Université de Caen, in Lower Normandy, an institution I am proud to call one of my alma maters! Allez Phénix!