Emma Diruf Seiler (1821-1886) was a Bavarian-American voice teacher and scientist who wrote and published Altes und Neues über die Ausbildung des Gesangorganes mit besonderer Rücksicht auf die Frauenstimme (Old and New in the Art of Singing, with Special Attention to the Female Voice) in 1861 while working in Leipzig. It was translated by William Henry Furness and published in Philadelphia as The Voice in Singing in 1868. This pedagogue and her writings are largely unknown to those who study historic bel canto pedagogy. In the opening of Seiler's pamphlet, she explained her purpose for writing was "to bring into harmony things which have always been treated separately, the Science and the Art of Singing..." Aside from brief comments in a few books on vocal pedagogy, Emma Seiler is largely unknown. Neither her contribution to voice science and pedagogy, nor the impact of her integrated philosophy on teaching have been subjected to scholarly scrutiny. The purpose of this document is to explore her philosophy on teaching, her method of female vocal instruction, and her impact on voice instruction. This dissertation historicizes evidence-based pedagogy through Seiler's example.