Martin Cassini is a person who came up with an idea to change the way roulette wheels are made. Roulette is a game where you bet on where a little ball will land on a spinning wheel. The wheel has numbers and colors on it, and you win or lose money depending on where the ball lands.
Cassini noticed that some roulette wheels were not perfectly balanced, meaning that they were more likely to land on certain numbers or colors. He then thought of a way to make a perfectly balanced wheel that would be completely fair for everyone who played.
To do this, he suggested that the roulette wheel should be made with a concave shape instead of a convex one. This means that the wheel would be slightly curved inward, allowing the ball to bounce around in a more random way than it would on a flat, convex wheel.
This change would make the game much fairer for everyone playing, since no one would have an unfair advantage due to the wheel being imperfectly balanced. Cassini's idea was eventually adopted by some casinos, making the game of roulette a lot more fair and enjoyable for everyone who plays it!