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Denmarks Edison

The phonic wheel motor invented by Poul la Cour in 1878. By using the phonic wheel motor up to 100 telegrams could be sent simultaneously on the same wire.

It was no coincidence that Poul la Cour became known as ”The Danish Edison.” In addition to his job as deputy director at the Danish Meteorological Institute, he worked with many inventions. A significant area of interest for la Cour was the telegraph system, which at the time was undergoing rapid development. At that stage, only one message could be sent at a time and often the line was busy. This was a great disadvantage, especially within the field of meteorology where fast communication over long distances was important.

Poul la Cour worked on a method to let several telegraphists use the same wire simultaneously, and in 1874, he was awarded the gold medal from the Danish Scientific Society for his work on the phonic telegraph system. By using this system, each telegraphist could send Morse code through an electric tuning fork to generate his own frequency on a single wire. 

In 1878, la Cour further developed his method, creating a phonic wheel motor that made it possible to send up to 100 telegrams at the same time. He was in fierce competition with the famous American inventor Thomas A. Edison, who only managed to send four telegrams simultaneously.


The cratostat

Poul la Cour’s amazing passion for research and development led to inventions in other fields as well.

In 1891, he invented the cratostat, a mechanical device that completely evens out uneven movement. This invention became extremely useful when la Cour later tested blade models in a wind tunnel. The cratostat was also used in cream separators in dairies and in steam turbines on ships.

The engine room was equipped with the drive belt tensioner of the test turbine. The drive belt tensioner was a mechanical device which evened out the uneven pulling force of the wind turbine

Another invention was the ”Poul la Cour key,” an electrical instrument used to control the electricity from the wind turbines.

His research in storing energy by using hydrogen helped him invent autogenous welding. He tried to commercialize his research by opening a factory producing oxygen and hydrogen, but was unsuccessful.

During his hydrogen experiments, la Cour discovered a way to make soda ash by using electrolysis. He believed that small-scale production of this product would be beneficial for those farms that had their own wind power units.

As a result of the experiments with the production and storing of hydrogen, he invented the ideal hydrogen lamp, which lit the rooms of Askov Folk High School for many years. It is also worth mentioning his invention of a compressor and a combustion engine fueled by hydrogen.


Poul la Cour invented many other things, but he never became a wealthy man.  He never gave much thought to business matters, focusing instead on how his inventions could benefit Denmark’s rural population. On several occasions, he sold the patents outside of Denmark for a small sum of money, with the only condition that the invention could be freely produced and sold in Denmark.