This paper examines the type of theory used to justify the application of physical scale modelling to the solution of mid-nineteenth century engineering problems. To do this, it discusses three particular examples: the initial Britannia Bridge breaking experiments of E. Hodgkinson, the vibrating railway bridge experiments of R. Willis and G. G. Stokes; and the ship resistance experiments of W. Froude. The theory invoked in these case histories is viewed against the background of the response of the contemporary engineering community (...) and compared with the notion of engineering science as proposed by W. J. M. Rankine. (shrink)

In the seventeenth and eighteenth centuries, mathematicians and physical philosophers managed to study, via mathematics, various physical systems of the sublunar world through idealized and simplified models of these systems, constructed with the help of geometry. By analyzing these models, they were able to formulate new concepts, laws and theories of physics and then through models again, to apply these concepts and theories to new physical phenomena and check the results by means of experiment. Students’ difficulties with the mathematics of (...) high school physics are well known. Science education research attributes them to inadequately deep understanding of mathematics and mainly to inadequate understanding of the meaning of symbolic mathematical expressions. There seem to be, however, more causes of these difficulties. One of them, not independent from the previous ones, is the complex meaning of the algebraic concepts used in school physics, as well as the complexities added by physics itself. Another source of difficulties is that the theories and laws of physics are often applied, via mathematics, to simplified, and idealized physical models of the world and not to the world itself. This concerns not only the applications of basic theories but also all authentic end-of-the-chapter problems. Hence, students have to understand and participate in a complex interplay between physics concepts and theories, physical and mathematical models, and the real world, often without being aware that they are working with models and not directly with the real world. (shrink)