Photo credits

The Embalse de Riano in northern Spain. The picture was taken by .... me!

Thursday, August 21

Nail analogies

so, many months ago I gave up biting my finger nails. I achieved this largely by measuring them individually every few days and drawing a chart to show their growth. Thus every time I bite a nail, it shows up as an ugly downturn in the line on the graph.

I also have a similar graph for the total of all my nails, which I am going to try to attach to this post, technology permitting. If succesful it will be here: ....

The thing I note about the graph is that it rockets upwards at an almost steady state until the nails start to overhang the end of the finger. (There are actually several milestones or markers: there is the point at which the nail literally pokes out beyond the finger, and can be seen from below. Then, closer in, there is the point at which the nail is supposed to be physically attached to the finger as opposed to just being in contact with it. At this point there is a kink in the skin. next in is the point at which my recovering nail starts to leave the nail bed and launch out into the void. Further back is the point at which my recovering nails are attached to the nail bed in the way that they hould be. and then closer in still, is the now barley visible point marking the wrost extent of my nail biting before I stopped.) Onec the nail starts to grow beyond each of these points it becomes progressively more vulnerable to general wear and tear in addition to the increased temptation to bite. I can ofset the urge to bite by thinking about how I don't want a dip in my graph, but there is little that can be done about the wear and tear. So now that the nails extend beyond the finger tip, I have developed an almost feminine obsession with nails and complain loudly to the whole house if I break one. Partly because I now understand tath this actually hurts, but mainly becasue I am saying goodbye to three weeks of growth.

So back to my graphs, and why my post title is about analogies.

I postulate that nails are analogous to cigarrette smoke and to a hydraulic jump (the transition between supercritical and subcritical flow conditions) in an open channel of water.

You see, the cigarette smoke rises as a smooth column until the friction of the air slows it down enough, and then it becomes much jmore billowy. And the water in the channel shoots along it until the friction overcomes it and it reverts to a deeper slower flow by going through a big wave. You also see a hydraulic jump in your kitchen sink every day - it's that wave forming a ring around the point where the water from the tap hits the stainless steel. In both the cigaratte smoke and the water, you get relatively smooth fast jet up to a certain point and then it becomes chaotic. Similarly my nails grew bice and smoothly up to the point where they overhung the finger tip, and then with random breakages on top of occasional bites the line on the graph becoes very volatile.

Strangely, there is also a link to my cheese consumption: more cheese correlates to faster fingernail growth. But that's another story.

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