The second half of the century saw much less revolutions than the first half. There’s multiple reasons for this. First, nationalism spread throughout Europe. Second, the liberal reform. Third, the higher standard of living. Through these points we can start to see the unification of Europe, and the the Europe we know today.
At this point in time, the rise of nationalism, countries were unifying; rather than revolting. First, there was the unification of Italy. Northern Italy started to unify when a war was started with Austria (Austria started the war, because Piedmont was irritating them), and France was called into help. Austria was defeated, and Italy received Milan and Venice. Southern Italy began to unify when Guiseppe Garibaldi, a goat farmer, started a group of supporters, the Red Shirts. Garibaldi and the Red Shirts landed on the shore of Sicily, and as they marched along gained others. This led to the control over Sicily, Naples, and most of Southern Italy; with the exception of the Papal States. Then Garibaldi gave the land to Piedmont, and returned to his farming days. Germany also started to unify under Bismarck.
Liberal reformation also was a factor in the drought of revolutions. In England, laws passed such as the Factory Act of 1833 and of 1844, Mine Acts 1842, Reform Bill of 1832 and of 1867, proved to the English that England was capable of Liberal Reform, so there was never huge reason for a revolt. Austria created a new Parliament which appeased those of liberal ideas. The idea of liberal reform made the middle class of France support Louis Napoleon and his liberal ideas. Other countries followed suit, and the spread of liberalism appeased Europe.
Lastly, the improved standard of living. Countries all over were passing new laws, and inventing new things to improve that of the life of their people. For instance, England had passed many laws on factories and mines improving the working condition.