The deceptively simple task of making a mechanism which would turn forever has fascinated many famous men and physicists throughout the centuries. In fact, the basic tenets of engineering grew from the failures of these perpetual motion machine designers. This work offers an illustrated overview of perpetual motion machines and their inventors.

"In the royal and princely courts of Europe, artworks made of multicolored semiprecious stones were passionately coveted objects. Known as pietre dure, or hardstones, this type of artistic expression includes?paintings in stone,? which were composed of intricately cut separate pieces that were made into magnificent tabetops, cabinets, and wall decorations. Other works included vessels and ornaments carved with virtuosic skill from a single piece of rare and brilliant lapis lazuli, chalcedony, jasper, or similarly prized substance; exquisite objects such as boxes, clocks, and jewelry; and portraits of nobles sculpted in variously colored stones. Derived from ancient Roman decorative stonework, the art of pietre dure was developed in Renaissance Florence, where the manufacture of such objects was enthusiastically sponsored by Medici princes. Ideally suited for ostentatious display, the works sent an unmistakable message of wealth and political might that was understood in centers of power everywhere. From Italy the medium spread across Europeto Prague, Madrid, Naples, Paris, and later Saint Petersburg. Precious and fragile, pietre dure objects are rarely brought together in large numbers. This richly illustrated catalogue contains more than 150 masterworks from across Europe, dating from five centuries, including almost every artistic use of semiprecious stone during this time as well as some of the finest examples of the medium. Eight essays by European and American experts discuss the individualized development of pietre dure in every European region, the latest developments in scholarship, the interrelationships between art and dynastic politics and between cultures, and a variety of techniques used to produce these luxurious masterworks."--Metropolitan Museum of Art website.