Poul La Cour - Telegraphic Inventor

Telegraphic Inventor

After having finished his studies in physics and meteorology in Copenhagen in 1869 Poul la Cour travelled in Europe to study practical meteorology. He received his most important inspiration from the Dutch meteorologist de Buijs Ballot, with whom he spent a month. He became convinced that Denmark should set up a planned meteorological institute according to the principles of de Buijs Ballot. During the next five years his life was closely interwoven with the early history of the Danish Meteorological Institute, which was founded in 1872 with him as a Deputy Director.

Telegraphy, the most important technological prerequisite for modern meteorology, soon became his main interest. In June 1874, the year in which Edison invented his quadruplex telegraphy, la Cour invented a telegraphic device based on tuning forks. The idea was to permit a number of telegraphers to send messages on a single wire, each using his own frequency. By using the resonance phenomenon of tuning forks is was possible to split out the messages at the receiving end of the wire. He patented his invention in London on September 2, 1874, but in the United States Alexander Graham Bell, Elisha Gray and others had been working along similar lines, which resulted in protests against his American patent applications. Having too little money to pay lawyers, he gave up his claim in America, and this invention was credited to Elisha Gray. La Cour however maintained that Gray had been working on the invention of the telephone, and only had changed his invention at the instant la Cour’s American application was published. He could not help feeling some malicious pleasure when Graham Bell was awarded the telephone patent by applying only a few hours before Gray - as he later wrote in an autobiographical article.

In 1876 la Cour could demonstrate 12-fold telegraphy with his system, and the Great Nordic Telegraph Company was interested in it for some time. However, only the Danish Railroad Company seems to have used his invention in Denmark. After the disappointment on the American market, he produced a new invention, the phonic wheel - a synchronous motor driven by a tuning fork, which used an electromagnet to rotate the cogwheel of the motor by one tooth for each vibration. With two synchronous phonic wheels at a distance, a multitude of telegraphic devices was possible. This time there were no problems with the patent. The invention was produced in August 1875, patented in 1877, and the details were published in the book The Phonic Wheel in 1878 in a Danish and a French edition. At that time the invention was adopted by the American company The Delany Synchronous multiple Telegraph, and a new fight of priority arose. In 1886 the Franklin Institute awarded la Cour the John Scott Legacy Medal for the phonic wheel and at the same time presented Delany with the Elliott Cresson Medal for the synchronism, a decision la Cour protested against.

The phonic wheel was used (in the form of Delany’s multiplex telegraphy) on some telegraph lines on the East Coast of the U.S.A., and in the London Post Office. It was used as a chronometer, which was accurate to 0.00004 second in short time measurements. The most modern application was in the mechanical “television” of Paul G. Nipkow (1884).