Yule Harmonic analyser made by Cambridge Instrument Company Ltd. Pat. No. 14928, 1894, in box, with five gear wheels

Graphic visualisation of data has helped mathematicians to analyse suspected periodicity and find patterns. This instrument, when a polar planimeter’s tracer is attached to a point on the radius of the disc, can analyse the expansion of a given curve’s periodicity. English mathematician George Udny Yule presented this type of a harmonic analyser that uses planimeters (instruments that measure the area inside a closed curve) in 1894 as a simpler to use device than previous analysers. It formed part of his work on time series analysis as described on one of his famous papers in 1927 where he introduced the idea of ‘disturbances’ over time for recurrent phenomena such as the motion of a pendulum. Time series analysis can help understand data and the graphs that they produce over a period of time and so assist with the prediction of future trends and patterns, especially useful in business.