Callen, Father Nicholas Joseph

Father Nicholas Joseph Callen (1799-1864) was a priest and scientist from Darver, Louth.   He was educated in an academy in Dundalk, where he began his training for the priesthood in Navan seminary before passing to Maynooth in 1816.   His initial training and mentoring in experimental physics came from Dr. Cornelius Denvir who had experimented with electricity and magnetic phenomena.   Callen went to Rome in 1823 and while studying in Sapienza University he became acquainted with the leading work of his day of Galvani, Volta and others.   He returned in 1826 to Maynooth as Professor of Natural Philosophy. And from 1834 he developed, from the base developed by Faraday and Sturgeon, his invention of the induction coil which is his major invention.   This invention was a prototype induction transformer and was described by Callen as a ‘repeater’ because of the inclusion of a dipping cup of mercury that periodically broke the circuit.   The fact that the secnd par of his circuit contained a coil, historically makes Callen the inventor of the transformer.   He is however remembered for many electrical and magnetic inventions and for the vital development work of extending the size of batteries and magnets.   In 1837 he developed with a clockwork mechanism a giant ‘repeater’ estimated to produce voltages of 600,000 V that generated a 380mm spark.   Frustrated by his inability to obtain batteries of sufficient size he devised improved designs and in 1849 details of ‘The Maynooth Battery’ were published.   Shortly thereafter this Maynooth Battery was commercialised in London as it had a number of vital advantages but significantly used cast iron rather than platinum and was based on a single solution rather than two used in batteries devised by Grove and other contemporaries.

Callen later connected 577 of his batteries in series and devised a method based on the electromagnetic lifting power of his current to provide an objective measure of the strength of his battery bank.   He reported lifting 2 tons which is a testament both to his batteries and to the design of his electromagnet.   At an earlier stage he used students holding hands in a circle to test the power of the currents, removing students incrementally until they could not bear the pain!   Clearly, these battery innovations were important and supported the enormous practical drive of electrical technology as it became an industrial science in the second half of the 19^th century.   The need for the industrialisation of electrical sciences appears to be anticipated by the Louth man.   Callen died in 1864 and is buried in the College.   NUI Maynooth has the Callen Building and the Nicholas Callen Memorial Prize to recognise one of the most important physicists, whose achievements rival those of Michael Faraday with whom he was compared in his day.

Reference

O’Hara, James G, (2004) Callen, Nicholas Joseph (1799-1864), Oxford Dictionary of National Biography, Oxford University Press.