The beginning
The concept of a set of gauge blocks that can be used to assemble a gauge to accurately represent almost any practical length from a small number of pieces was invented by Carl Edvard Johansson (Figure 1), a Swedish machinist, in 1896 and therefore has more than a century of history.
Figure 2 illustrates a demonstration of gauge block wringing force performed by Johansson in 1917 at a mechanical engineering conference in Stockholm. A total of 200lb (more than 90kg) of weights were suspended from the lower gauge block. The wringing force was equivalent to that generated by a differential pressure of 33 atmospheres on the wrung surface area.
