This article investigates intervallic measurement and the tacit limitations engendered by a prevalent symmetrical perspective of measuring intervals. Various numerical and instrumental limitations and further detail of harmonic and melodic structures, such as Farey sequences, are illustrated. This approach distinguishes itself from a perspective of prime limits, explored by Harry Partch and others. A standardisation of ‘microtonal’ notation is not suggested; rather, the restrictions provided by any such standardisation are re-examined through an objective lens of ratios, to harness the generative potential of numbers. An orchestration-led approach to composition is described, where the tuning limitations of instruments are utilised for idiomatic composition. Tuning practices that ‘evade’ the octave are also discussed, including gamelan, mbira and three scales found by Wendy Carlos. The article concludes with a section on the construction of harmonic systems in the absence of instrumental influences.