The Cat's Purr: No one is sure why or how they do it.

Cats Purring: No one really knows how or why.
Hi tribe: This senile contributer is a cat lover...also a dog lover, budgie lover, spider lover and in reality rather fond of all the myriads of life forms who share our planetary adventure. The exception, due to their neurotic behavoir, is some homo Sapiens...you and me.
I digress. Those of us who have kept felines are familiar with that warming sound, The Purr. We are usually so busy enjoying our moggie as he or she appears to be happy while purring, we rarely wonder why, or especially how, the puss makes this attractive, rumbling sound.
Here we have mankind, a blindingly intelligent life-form, who is about to conquer the stars, is able to ponder on his very being, has unlocked the secrets of its home, Planet Earth, and has produced literature and great music that will remain evergreen, along with much more magnificent endeavour.
So why are we so befuddled at the sounds Kitty makes?
A few years ago, authorities such as the late veterinarian and broadcaster, David Taylor, included the domestic feline in his long-out-of-print book, "Talking Animal." I was most impressed with his erudite explanation of how a cat purrs "...purring is not a voice, it is the vibration of blood in a large vein in the chest cavity, etc." Evidently, Taylor explains, "the blood flow is constricted by nearby muscles and the resulting vibrations are amplified by the air-filled bronchials and windpipe." This scholarly treatise impressed me at once...turns out it might have been all tosh.
There seems little doubt that one of the reasons for loud purring is to signal kittens to draw close to the mother cat for sustenance and protection. Taylor says female cats stop purring as soon as the kits suckle. The author can postulate no reason for the male cat's purring, unless the runt of the litter has a'hold of his gonads..
And why is this purring so satisfying and soothing for kittie's owner as her cat sits on her lap and buzzes contentedly away?
Really, no one seems to know why or how purring comes about.
Wikipedia, an authority on many things, says its theories in this instance are no more than "Speculation." The provider does, however, tell us that purring is not limited to cats and a whole host of other critturs also purr: badgers, bears, tapirs and even gorillas while feeding! Sure that's not a "keep away" growl, Wiki?
Wikipedia also mentions a vague "neural oscillation" in the cat's brain, but says it is of "uncertain significance." I'm sure one of their eds. are getting a rollicking over this unfocussed article.
Unsurprisingly, leading pet food providers, Purina and Whiskas, weigh in with some useless additions to the current knowlege. We know what they are implying, "Cats purr when they are full of our tasty pet food - or they want some more."
Another hypothesis is the purring is produced with the cooperation of the larynx and vocal chords which then "contract the glotis." (part of the larynx). Why that produces a sound like a 250 Honda bike is not explained.
So cats do purr for reasons beyond just feeling happy. We have also read they purr when in pain occasionaly and this seems to release natural pain relievers (or an owners soothing strokes). We have said they purr to reassure and guide kittens. They may purr to ask for food, water or to be let out. These purring episodes are of different pitch and volume and can be detected on studying Tibby.
We are not even sure, based on what I have read today, that cats are even aware they are making a noise while purring. Sometimes quite a loud noise.
The record, evidently, is held by a moggie called "Smokey," who generated a shattering 67.7 decibells! He was later found in a weighted sack one night in the River Hudson, (just kidding).

So when you and your cat are having a quiet hour together accompanied by some harmonious purring, see if you can find any reason he might be doing it just then. Maybe you could add to the sketchy information available on the subject.