Editing Daniel Gabriel Fahrenheit (section)

===Work with thermometers, Fahrenheit  scale===
By around 1706, Fahrenheit was manufacturing and shipping barometers and spirit-filled thermometers using the {{ill|Florentine temperature scale|qid=Q130551159|s=1|v=sup}}.<ref name="momber">{{cite journal |last1=Momber |first1=Alfred |title=Daniel Gabriel Fahrenheit.; sein Leben und Wirken |journal=Schriften der Naturforschenden Gesellschaft in Danzig |date=1890 |volume=7 |issue=J }}</ref>{{rp|116}} In 1708, Fahrenheit met with the mayor of Copenhagen and astronomer, [[Ole Rømer]], and was introduced to [[Rømer scale|Rømer's temperature scale]] and his methods for making thermometers. Rømer told Fahrenheit that demand for accurate thermometers was high.<ref name="star" />{{rp|4}} The visit inspired Fahrenheit to try to improve his own offerings.<ref name="middleton">* {{cite book |author=Middleton, W. E. Knowles |title=A History of the Thermometer and its Use in Meteorology |year=1966 |location=Baltimore, Maryland |publisher=Johns Hopkins Press}}{{rp|71}}</ref> Perhaps not coincidentally, Fahrenheit's arrest warrant was dropped around the time of his meeting with Rømer.<ref name="star" />{{rp|3–4}}

In 1709, Fahrenheit returned to Gdańsk and took observations using his barometers and thermometers, traveled more in 1710 and returned to Danzig in 1711 to settle his parents' estate. After additional travel to Königsberg and Mitau in 1711, he returned to Gdańsk in 1712 and stayed there for two years. During this period he worked on solving technical problems with his thermometers.<ref name="star" />{{rp|4–5}}

Fahrenheit began experimenting with mercury thermometers in 1713.<ref name="star" />{{rp|26}} Also by this time, Fahrenheit was using a modified version of Rømer's scale for his thermometers which would later evolve into his own [[Fahrenheit scale]]. In 1714, Fahrenheit left Gdańsk for Berlin and Dresden to work closely with the glass-blowers there.<ref name="star" />{{rp|5}} In that year [[Christian Wolff (philosopher)|Christian Wolff]] wrote about Fahrenheit's thermometers in a journal after receiving a pair of his alcohol-based devices, helping to boost Fahrenheit's reputation in the scientific community.<ref name="middleton" />{{rp|74}}

In addition to his interest in meteorological instruments, Fahrenheit also worked on his ideas for a mercury clock, a [[perpetual motion machine]], and a [[heliostat]] around 1715. He struck up a correspondence with [[Leibniz]] about some of these projects. From the exchange of letters, we learn that Fahrenheit was running out of money while working on his projects and asked Leibniz for help obtaining a paid post so he could continue his work.<ref name="star" />{{rp|5–7}}

In 1717 or 1718, Fahrenheit returned to Amsterdam and began selling barometers, [[areometer]]s, and his mercury and alcohol-based thermometers commercially.<ref name="star" />{{rp|8}} By 1721, Fahrenheit had perfected the process of crafting and standardizing his thermometers.<ref name="star" />{{rp|24}} The superiority of his mercury thermometers over alcohol-based thermometers made them very popular, leading to the widespread adoption of his Fahrenheit scale, the measurement system he developed and used for his thermometers.<ref name="Grigull, Ulrich 1966 pp. 9"/>