basically this is a vast collection of various mechanical designs, showing how previous people have solved problems. There is little critique of the designs, so some may prove weak, or difficult, but it is an excellent sourcebook for ideas. in this age of CAD and modelling, it's not hard to take ideas from this book, and test them in your designs. There is some repetition in the designs (less than 5% of the designs) but once you look at the designs there are subtle differences which may matter in your work.