The earliest example of equine footwear we have is made of animal hide and dates from about 600 B.C. This primitive hoof protector looks more like a horse bootie than what we think of today as a horseshoe. It was probably stuffed with dried grass or other available natural material and tied on with hide thongs.
The spiral model is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts. The spiral model was defined by Barry Boehm in his article A Spiral Model of Software Development and Enhancement from 1985. This model was not the first model to discuss iterative development, but it was the first model to explain why the iteration matters.
Spiral pipe (helically welded pipe) has been produced industrially in the U.S. since 1888. Production technology for longitudinally welded and helically welded pipe developed more or less in tandem, but somewhat staggered in time, which resulted in some pipe being applied in operations for which they were not produced.he real issue is not whether a pipe is helically welded or longitudinally welded; the issue is who made the pipe and what technology was used with what experience â regardless whether it is longitudinally or helically welded pipe.