Book excerpt: The method of computation using the hydraulic apparatus developed by the author is based on the application of principles of hydraulic analogies in correlation with partial use of the principles of computation based on finite differences. The application of these hydraulic computers allows one to find the approximate numerical solutions for a whole class of differential equations. Therefore, these machines might be called hydraulic integrators. Insofar as the application concerns itself with the solution of differential equations, it is possible to use this method to solve problems in many different fields of technology. To approach the problem more concretely, and for clarity of presentation, we look at the applications of thermodynamics to civil engineering and the problems that can now be solved by this method. (Author).