Claim: Fowler Calculators was a manufacturer of slide rules which is closely related to nomograms.
Evidence: Fowler Calculators Ltd was a manufacturer of slide rules and other scientific and mathematical instruments, based in Manchester, England and founded by William Henry Fowler. As graphical analog calculators, slide rules are closely related to nomograms, but the former are used for general calculations, whereas the latter are used for application-specific computations.