Whom and what should people trust or distrust? This question has long been a prominent concern not only in everyday human transactions but also in the most abstruse domains of science, commerce, and technology. Both Steve Shapin and Ted Porter have shown the significance of this question in the complex relationship between trust and quantification. They demonstrate that, to a certain extent, Restoration natural philosophers and nineteenth century engineers were able to win greater trust for their claims by giving them quantitative expression. At the same time, though, Shapin and Porter map some of the important historical contingencies of the subject. Quantification has not always been achieved to the satisfaction of all, nor has it necessarily made claims uniformly more highly trusted by all parties. Therefore, to avoid facile transhistorical generalizations about the relations between trust and numerical work, the historian has to ask questions rather more socio–historically specific in nature.