Complex sentence: Studying ballistics, in 1890 he presented his first major work, "Erreurs d'Observation", to the "Académie des Sciences"; this stimulated the introduction of modern indirect fire methods.
Split into simpler sentences: Studying ballistics, in 1890 he presented his first major work, "Erreurs d'Observation", to the "Académie des Sciences". This stimulated the introduction of modern indirect fire methods.