I've answered a couple of you personally, but there have been several more requests so here we go.
Generally speaking, the system Mr. Shew showed me involved breathing for those
high compression situations that come up so often with trumpet playing. In
other words, this system is designed to encourage easy access to a fast air
stream. I know how weird this must sound to some of you already.
As we begin the inhalation, the belly button area expands a bit (not nearly as much as singers and most brass players encourage.) This step is only responsible for about 5% of the air intake according to Mr. Shew. As we continue to inhale, the chest expands dramatically. This is step two. Also during step two, the chest might rise and the belly button area returns to its original position. This step is responsible for about 75-80% of the air intake. On a side note, I reread Rafael Mendez's "A Prelude To Brass Playing" the other day and his description of the proper inhalation was very similar to Mr. Shew's up to this point. The next step, however, is where this method is pretty unique. Step three involves raising the shoulders!!! Apparently this allows the lungs to fill up more freely if we do it in a relaxed manner. Step four is to bring the belly button area in as if driving a "wedge" into the gut. We do this as aggressively as necessary for the phrase at hand. Step five is to return the shoulders to a lower position and the last step is to exhale. That's a total of 6 steps. It is pretty mechanical and slow at first, but after a few days of practice, the steps flow together, the whole breath can be taken in an eighth rest, and the rhythm/momentum of the whole process starts to work.
Personally, the part that has helped me the most is the added leverage my abdominal muscles have in pushing the air out when this area is not expanded as far as most people teach. Also, I used a scaled down version of this method for most of the playing I do. I know how different this must seem from how many of us were taught. All I can say is that it has been useful to me and me students, and it pretty well describes the way Doc has always appeared to breathe. I would strongly encourage anyone interested to get in touch with Bobby Shew. My apologies to him if my description isn't exactly right, but this gives everyone the general idea.
Since many of you have asked, I don't believe anyone is truly qualified to
teach Jacob's approach to breathing except Arnold Jacobs. So I won't even try
to compare the two systems except to say if they both work, then at their
essence there must be the same fundamental principles at work. Remember, the
primary application of Mr. Shew's system is to play high and loud.