Louis Melville Milne-Thomson was a smart man who lived a long time ago. He was really good at math and he liked to use it to study things that are very big or very small, like the shape of the Earth or the movements of tiny particles.
One thing that Louis Melville Milne-Thomson is famous for is his work on something called differential equations. Now, you might be wondering what that means. Well, you know how when you solve a math problem, you usually get just one answer? Like, if you add two plus two, you know the answer is four? Well, with differential equations, things are a little more complicated. Sometimes there isn't just one answer, there can be lots of different answers depending on different factors.
But don't worry, Louis Melville Milne-Thomson was really good at figuring out how to solve these problems. He also worked on things called complex functions, which are kind of like puzzles that involve really complicated math.
Overall, Louis Melville Milne-Thomson was a really smart guy who used math to understand some of the most complicated things in the world. And even though he lived a long time ago, we still use his ideas and techniques to solve math problems today!