Nicholas Callan Irish Inventor of the Induction Coil

Nicholas Callan was born on December 22, 1799, at Darver, near Dundalk. He was destined for the priesthood from an early age, serving as an altar boy and Mass server before he started his priesthood at Navan seminary. He entered St. Patrick’s College, Maynooth in 1816 where one of his teachers was Dr. Cornelius Denvir, who got him interested in the emerging sciences of electricity and magnetism. In 1823, after his ordination, he went to study in Rome where he was intrigued by the work of Galvani and Volta, two of the key pioneers in the study of electricity. In 1826, Callan returned to Maynooth after being appointed to the chair of natural Philosophy (the old name for Physics). He remained in that post until his death.


He set up a laboratory in the basement of Maynooth College, and soon added another terror to the life of the seminarians: electrocution. As there were no instruments available at that time to measure the strength of the current or the voltage, ever resourceful, Callan decided to use the students! His unfortunate victims included Charles Russell, later President of Maynooth, who was put into the hospital after receiving several ‘doses’ of electricity, and William Walsh, who later became Archbishop of Dublin, who was knocked unconscious by one jolt. After knocking out Walsh, Callan was banned from using students again and afterwards resorted to using chickens instead.

The Induction Coil

In 1836, Callan had his major breakthrough: the induction coil. He took a horseshoe shaped iron bar and wound it tightly with thin insulated wire, then loosely wound thick insulated wire over the top. He discovered that when he interrupted the current sent through the thick wire (primary coil), a high voltage current was generated in the unconnected thin wire (secondary coil). This is how a transformer works, going from low voltage in the first coil to high voltage in the second coil. Callan discovered that the faster that he interrupted the current, the bigger the spark. In 1837, he built a giant induction machine that could interrupt the current 20 times a second. It generated 15-inch sparks at around 600,000 volts, and was the largest artificial bolt of lightning seen at that time.

The Maynooth Battery

Since batteries at that time could not produce enough power for Callan, he invented his own: the ‘Maynooth’ battery in 1854 and the single fluid cell in 1855. Previous batteries used a Zinc plate and Platinum (which worked but was expensive) or Carbon (which was cheap but did not really work). Callan used a treated cast-iron instead. His first battery put the zinc in a filled porous pot in the centre of a filled cast-iron casing. He later realised he could get rid of the pot and one of the fluids and just put the zinc inside an acid-filled cast-iron casing to achieve the same result. Unable to measure the voltage, Callan measured the batteries power by connecting them to an electromagnet and seeing what they could lift. His best battery lifted two tons! Again he tortured seminarians by making them do tugs of war against the electro-magnet, switching off the power just when they made their greatest effort, dropping them on the floor to the amusement of himself and the onlookers.

Electric Motors

He also built electric motors, travelling around his lab on an electric-powered trolley, and worked on creating an electric train, but was forced to admit that even his batteries were not powerful enough to run it.

He was an eccentric but a genius and he was summed up beautifully by one worried student: ‘Many are afraid he will blow up the College…but he is a very holy priest.’ Callan died from natural causes at Maynooth on January 10 th 1864.