Hermann von Helmholtz

Hermann von Helmholtz married Olga von Velten, the daughter of a surgeon, on 26 August 1849. The couple had two children. His wife was of delicate health and she died on 28 December 1859, leaving Helmholtz with the young children.

In 1861 he married Anna von Mohl, the daughter of Heidelberg professor Robert von Mohl. This marriage produced three more children. Anna was an attractive woman, considerably younger than Helmholtz.

Hermann von Helmholtz suffered from ill health, including fits of depression, during his later years, and died on 8 September 1894.

Hermann von Helmholtz was born on 31 August 1821, in Potsdam, Kingdom of Prussia, as the eldest of four children of Ferdinand Helmholtz. His father was a teacher of philosophy and literature at the Potsdam Gymnasium.

He grew up in an intellectually stimulating environment and was taught classical languages, as well as French, English, and Italian by his father. His father was a close friend of the philosopher Immanuel Hermann Fichte, and introduced the boy to the philosophy of Immanuel Kant and Johann Gottlieb Fichte. His upbringing greatly influenced the development of his own philosophical views.

Helmholtz received his primary education from Potsdam Gymnasium and wanted to study natural science. However, his father did not have the funds to send him to the university and instead asked him to study medicine as the government provided financial support for medical students.

He obtained a government stipend for five years’ study at the Königlich Medizinisch-chirurgische Friedrich-Wilhelms-Institut in Berlin. In return he had to commit himself to eight years of service as an army surgeon. At the institute he studied clinical medicine under Lucas Schönlein, and physiology under Johannes Müller.

He also took courses in chemistry and privately read the mathematical works of Laplace, Biot, and Daniel Bernoulli as well as the philosophical works of Kant. While working on his dissertation under Johannes Muller, he became acquainted with Muller’s other students including Ernst Brücke and Emil du Bois-Reymond. He graduated from medical school in 1843.

Following his graduation, he was appointed an army surgeon at the regiment at Potsdam. His army duties were few and thus he had ample time to devote to his research. He had varied interests in a number of fields and his job left him with enough time to explore his interests.

Hermann von Helmholtz’s first important scientific achievement came in 1847 with the publication of his theories in his book ‘Über die Erhaltung der Kraft’ (On the Conservation of Force). He drew inspiration for his research from the earlier work of Sadi Carnot, Émile Clapeyron and James Prescott Joule.

In 1848, he was appointed assistant at the Anatomical Museum and lecturer at the Academy of Fine Arts in Berlin. The very next year he moved to Königsberg, in East Prussia, to become assistant professor and director of the Physiological Institute.

While working at Königsberg in 1849, Helmholtz measured the speed at which the signal is carried along a nerve fiber. He used a recently dissected sciatic nerve of a frog and the calf muscle to which it attached to perform the experiment, and used a galvanometer as a sensitive timing device. He reported transmission speeds in the range of 24.6–38.4 meters per second.

He was also an inventor and revolutionized the field of ophthalmology with the invention of the ophthalmoscope in 1851. The instrument he developed could be used to examine the inside of the human eye. This invention proved to be an extremely popular one and earned him considerable fame and acclaim.

One of Hermann von Helmholtz’s major contributions to science was his work in the law of conservation of energy. He drew inspiration from the previous works of Joule, Sadi Carnot and Émile Clapeyron, and arrived at conclusions similar to Grove's. He then published his findings in the book ‘Über die Erhaltung der Kraft’ (On the Conservation of Force) in 1847.

He revolutionized ophthalmology with the invention of the ophthalmoscope, an instrument that allows a health professional to see inside the fundus of the eye and other structures. The device is extensively used for determining the health of the retina, optic disc, and vitreous humor.