In 1724 he published his first mathematical work. He submitted it to the Paris Academy and won the prize of the Paris Academy the following year. Therefore he got the chair of mathematics in St. Petersburg, where he taught from 1725 to 1732. He worked together with Leonard Euler, a Swiss mathematician and physicist, on his most important work, the Hydrodynamica. But being unhappy in St. Petersburg, he went back to the University of Basel, where he taught botany and then physics.
Daniel's most important work was Hydrodynamica. This was about the movement of fluids. He is also known for his work in calculus and probability theory. Between 1725 and 1749, Daniel also won many prizes for other work in fields like astronomy, gravity, tides, magnetism, and ocean currents.