Nicholas Callan – the induction coil

Rev Nicholas Callan. Picture: Maynooth College collection

THE Rev. Nicholas Joseph Callan was born in County Louth in 1799 and as a youngster he served as an altar boy in the local church before going on to the seminary in Navan, Co. Meath and then to St Patrick’s College, Maynooth in 1816, Ireland’s national seminary for the training of priests.

At Maynooth Callan studied ‘natural philosophy’ the precursor of modern physics, under Cornelius Denvir. Denvir who would later become a bishop was enlightened for the time in his teaching techniques and encouraged his students to experiment. It was from Denvir that Callan first developed his interest in the study of electricity. In 1823 Callan was ordained as a priest and went to Rome to obtain his doctorate in divinity in 1826. At the time Italy was a centre for early research into electricity and here Callan became familiar with the work of the Italian physicist Alessandro Volta who had developed the world’s first battery. Callan returned to Maynooth where he was made chair of natural philosophy, a post he would hold until his death.

Throughout his career at Maynooth he was active in research into electricity and in 1836 made his best known invention, the induction coil. He had been working for a number of years on developing a more powerful battery than those that were currently available to enable him to further his research. He came up with a simple design using cast-iron as opposed to the common batteries of the time that used platinum; his ‘Maynooth battery’ was much cheaper to produce and was a success, it went into commercial production in London and was used for a number of practical applications including lighthouses.

His work on the Maynooth battery led to further investigations in how to generate more energy. He developed a giant battery that was able to produce enough power to lift a two ton weight with a magnet but the battery itself was huge requiring more than 500 Maynooth batteries using 30 gallons of acid. It was from this work that he came up with the very first induction coil, effectively the first electrical transformer. By connecting two copper wire coils to a battery and electro magnet and then interrupting the current he was able to generate a massive increase in voltage. In this way smaller batteries could generate much larger electrical charges. His 1837 version that used a clock mechanism to interrupt the current 20 times a second is estimated to have produced 600,000 volts – the largest artificially generated charge at that time.

Callan’s pioneering work was largely forgotten after his death in 1864 as Maynooth was a religious college there was little interest from the hierarchy in his discoveries; for many years the invention of the coil was attributed to the German scientist Heinrich Ruhmkorff who had successfully commercialised the idea. It was not until the 1950s that Callan’s true contribution became widely recognised. As well as the coil he was one of the first to understand the principles of the electrical dynamo. He is also credited with creating an early electric vehicle, a trolley he used in his lab and developed a method for galvanising Iron.

In the late 20th century he was fully recognised by the Institute of Physics and Institute of Electronic and Electrical Engineers. His old college at Maynooth is now part of the National University of Ireland where the Callan Building is named after him and in 2000 the Irish government issued a stamp in his honour. He is buried at Maynooth.

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