How it began
Nicholas Joseph Callan was born in 1799 near Dundalk, County Louth, and trained for the priesthood at Maynooth College in County Kildare. After ordination he studied in Rome, where he met current work on electricity. In 1826 he returned to Maynooth as professor of natural philosophy, a post he held for the rest of his life. He began work on the idea of the induction coil in 1834 and built the first one in 1836.
How it works
An induction coil uses electromagnetic induction to transform a low voltage into a much higher one. Callan wound copper wire in many turns around an iron core. Interrupting the current in one winding induces a high voltage in the other. Callan also designed the Maynooth Battery, which used cast iron to make batteries more efficient, to power his experiments.
Who pushed back
Callan worked in a Catholic seminary, outside the circles of Trinity College and the Royal Society in which the Anglo-Irish scientists of his day moved. One account says that this location and his lack of connections to the main scientific networks left his work often overlooked.
What lasted
The induction coil became essential to electrical and electronic technology. Later applications named in the sources include the spark plug in a car engine, radio and X-ray machines. Callan died in 1864. Awards and buildings at Maynooth carry his name.
