A proportional measuring instrument used to transfer points from a model while enlarging or reducing them according to a constant geometric ratio.
Comparatore di proporzione is an instrument for transferring measured points from a model at a proportional scale. The system preserves angular relationships and converts the measurements according to the chosen enlargement or reduction ratio.
Le voci del marmo notes a Pietrasanta variant known as the strumento del Giannoni, a specific comparator patented by the craftsman Renzo Giannoni.
Etymology
Italian: comparatore, “comparator,” + di proporzione, “of proportion.”
Sculptor Notes
This instrument solves a different problem from a standard 1:1 pointing machine: it allows the geometry of a small model to govern a larger stone while maintaining a controlled scale relationship.
References
https://levocidelmarmo.sns.it/scheda_oggetti_relazione.php?denom=comparatore+di+proporzione&id=37