Some recent research has suggested that use of the passive voice in scientific writing has declined over the last few years. This study attempts to see to what extent that is true. The corpus consists of 32 scientific articles with 8 taken from the publications of the Royal Society of London for each of the years 1985, 1995, 2005 and 2015. Half of the articles are from Series A (physical sciences) publications and half from Series B (biological sciences). Overall there is some evidence that passive use has declined for multi-authored papers, although this is clearer in Series A than in Series B. This is supported by an increase in the use of active verbs with first person pronoun subjects in Series A multi-authored papers. There is a tendency for active verbs with first person pronoun subjects to occur in mental process rather than material process. It is hypothesized that the more personal nature of mental process lends itself to active first person pronoun use, and that an increase in articles based on mathematical modeling, as opposed to experimental reports, has led to an increase in the proportion of mental process verbs, particularly those related to mathematical calculation.