>Soon after the '356 patent issued, the Water Bed Institute, a trade organization, hired patent attorneys to review the validity and scope of the '356 patent. The following report appeared in a letter circulated to Institute members on September 1, 1971: "On the basis of an initial and preliminary analysis of the Hall patent, the patent in question is probably not of major consequence to the water bed industry. The attorneys state that in their opinion it would be inadvisable at this time for members to rush to sign up to pay royalties for use of the patent. The patent is limited in scope, and should not be of major concern to the water bed industry." Other attorney opinion letters reporting the conclusion that the '356 patent was invalid, such as the October 1973 analysis performed for Hodel & Co., were circulated among members of the industry. The belief that the '356 patent was invalid, already widespread in the industry by 1973-74, appears to have been reinforced by Hall's failure to assert it against anyone in litigation during that time period. In no small part because the modern waterbed had been pretty well described to a T by [Robert Heinlein over 20 years previously:](http://en.wikipedia.org/wiki/Waterbed) > "I designed the waterbed during years as a bed patient in the middle thirties; a pump to control water level, side supports to permit one to float rather than simply lying on a not very soft water filled mattress. Thermostatic control of temperature, safety interfaces to avoid all possibility of electric shock, waterproof box to make a leak no more important than a leaky hot water bottle rather than a domestic disaster, calculation of floor loads (important!), internal rubber mattress and lighting, reading, and eating arrangements—an attempt to design the perfect hospital bed by one who had spent too damn much time in hospital beds."