This recent question about a time traveller who visits Newton reminded me of this short story, which I think I read in Omni in the early 1980's.
A man travels back in time, hoping to spare Isaac Newton the bother of making tedious calculations by giving him a calculator.
Unfortunately
Newton thinks the calculator is the work of the Devil and attacks the man, who retreats to his own time. Newton abjures doing science from that moment on.