As a result of Matthew Trainer's recent on 'Kelvin and piezoelectricity', this paper discusses the way to approach past science. It stresses that the writing on the history of science must (1) be based on reliable sources (i.e. primary sources and historical researches); (2) be sensitive to the differences between past and present science; and (3) be informed about the wider context of the scientific activity under study. Scientific journals have a responsibility to see to it that the historical components of their articles meet these standards. This is a reply to Shaul Katzir's comment on 'Kelvin and piezoelectricity' (Trainer 2003 Eur. J. Phys. 24 535-42). The author gives further support to his belief that Kelvin was instrumental in helping to establish the science of piezoelectricity. Kelvin's instruments played an important role in its discovery and his theory on pyroelectricity, a phenomenon closely connected to piezoelectricity, served as a basis for developing the theory of piezoelectricity. In support of this, the author has included extracts from the scientific writings of J J Thomson (Nobel prize for physics, 1906) in 1914.