Interactive Figures

As discussed elsewhere in these fora, the relationship between analysis, creativity, and tools is a neat dynamic. One of the kinds of jobs I have taken on in the last decade or so is to add material to legacy texts to keep them profitable. For engineering material, old texts often involve complex figures on paper. In decades past, students might spend significant time learning to read and interpret such figures. Translating those figures for simple use on a screen is probably really boring to a lot of people, but for me it is a neat challenge simply because I have an adequate toolkit for the job and a tolerance for the associated tedium.

To illustrate the idea, I offer two cases popular in chemical and mechanical engineering curricula of yore: (1) reading a generalized compressibility chart to quantitatively assess deviations from ideal-gas behavior and (2) reading a so-called psychrometric chart to get the physical properties of humid air.

The Nelson-Obert generalized compressibility charts (L. C. Nelson and E. F Obert, Generalized Compressibility Charts, Chem. Eng. 61:203 (1954)) have been useful in education well beyond their practical utility in design calculations; for the later, complex equations of state are easier to use and more accurate and precise than charts. However, the qualitative behavior of such equations is not readily accessible to the novice.

Simplified compressibility chart from Daniele Pugliesi – Own work, CC BY-SA 3.0,

You may view the 1954 charts here:

You may recall from readings in chemistry or physics that the van der Waals equation explains deviations from ideal-gas behavior with two parameters: a volume correction and a pressure correction representing a rigid volume and an attractive potential respectively. Those parameters are reflected in the z < 1 and z > 1 values in the compressibility charts. Such charts provide access to observed behaviors that may not be obvious from quadratic or cubic equations of state.

To translate such a figure to an interactive version, first digitize and fit all curves. Cubic splines are useful for fitting, but many techniques will suffice. After that, one needs an interpolation scheme to estimate values between the parametric curves. Examining whether to interpolate in p or 1/p or p3 , etc. is useful for achieving the best behavior.  One can then display the outcome in a tool like GeoGebra (You may interact with the result here: and spend time optimizing the interface for accessibility.  That sort of interactive display allows greater precision and accuracy in reading figures.

The second example is the psychrometric chart which displays dry-bulb temperature, wet-bulb temperature, dew point, enthalpy, humid volume, and absolute humidity of humid air.

from ArthurOgawa – Own work, CC BY-SA 3.0,

In this case, all quantities can be calculated at atmospheric pressure with ideal-gas behavior. It is just tedious. Nonetheless, a tool like GeoGebra enables an interactive figure; students can then use the figure without mastering the calculations (You may interact with the result here:

Even these days though, when I feel a bit of aimless creativity coming on, I sometimes yearn for a transparent straight edge and a large piece of paper.


In many social circles, my Dad was called Doc. The title was earned twice, but mostly the moniker paid respect to the fact that he was probably one of the cleverer of folks you could choose to be around.

His Dad was called Farmer. That was a bit of a question mark, since he taught agriculture. Sort of an inverse mode of address, a la Tiny in gangster movies.  Anyway when we’d walk to town together to get the mail, folks would wave and say “Hey, Farmer!”.   

Mom’s father was just called Pop. Seemed to be universal, but he never used any honorifics for anyone. You were either Bud or Sister.  Few words that man.

I tend to feel out of place if someone calls me mister or any of the other likely honorifics. I like either my given name or a functional role name in the context of the affair. So, I get it if there is an action in progress; it is important to have a chain of decision making.  I still answer to Bud though.   A lot of that is just taking the piss. But nothing really matters unless you answer to it.  

Then there is the sort of sarcastic honorific meant to intimidate. I used to get those calls on Sunday nights from mothers of failing college students. They’d pile on the titles in a vain attempt to cover a situation with confusion. It is a toddler’s tactic. Not unlike that which a few politicians practice.

You don’t have to call me “darling”, darling. But you never even call be by my name.

Lest One Forget

Gandma did not vote every year. It was too expensive. Grandpa pretty much went along with most things if they would slow down the talking. He was good that way.

This year it is too expensive not to vote.

Christmas 1926

One might first note that his penmanship is not bad for the circumstances. In other letters around that time he complains of wobbly chair legs and difficulty keeping a cigar lit. He was an avid if timid cigar smoker. Around about forty five years after that letter, he gave me some coins and asked if I would walk to town to get him a few cigars. He gave me details: Hava-Tampa Jewels.  The point was to deceive the beloved in the above letter. I played along. That was my first illegal purchase.  Let’s just say I was under 18, but nobody really cared or thought that I would ingest the tobacco.  Cannabis and cigars were two totally unrelated things in those days.  The regime was kind of like Merle Haggard’s Muskogee. If you don’t know it, you have to read the whole history of that song—hypocrisy on LSD.

But seriously, who gets away with secretly smoking a cigar? Seems like a misguided effort from the start.

Nonetheless, he and I were companions. He taught me how to tie fishing knots, plant row crops, harvest stuff at the appropriate time, and scavenge for caterpillars off catalpa trees (to be used as fish bait).   One should really look up catalpa trees if you didn’t grow up with one nearby.

He was the first of my ancestors to move out of farming and labor and sheer desperation into a profession. I don’t know, but I have a sort of romantic vision that his parents recognized that this dude was kinda smart. Regardless, they enabled his education by moving to where the schools were.  Academic achievement then became sort of a familial obsession.  His field was agriculture. He agreed to be a football coach (but he got his own ag building).

Grandpa did a Master’s thesis in the 30’s on the productivity of tenant farmers in what had previously  been  cotton land. It is kind of obscene in some ways, but a valid economic study in others. There were a few landowners. The rest were not.

To his credit, he helped folks get started growing peaches and was sort of on call as a livestock fix-it man for his part of the county. In payment, there were boxes of fresh corn and peas and squash and watermelon on the front porch; they appeared in the early AM on weekends

I don’t know any of the bad stuff other than him shooting off two fingers of his left hand. He was an accomplished quail hunter, but apparently a little over exuberant. The story I was told is that his companions brought him home and laid him out on the kitchen table. That was a little overwhelming for my kid brain and still is now. I do remember sitting with him on the back porch and watching him adeptly peel an Anna apple just picked using a thumb and two fingers to rotate the target.

But thanks to him, I am OK at asking questions and can fillet a fish with style, grace, speed, and a little respect.  

I do think about cigars from time to time; much of the land that surrounds my current playground was cigar-wrapper territory up until the 70’s or so.  I think more music would have helped Sam a bit. But alas grandma was a different story.


In the nights that I had some free time when living in a tiny apartment in the city center or needed to clear my head,  I’d just go for a walk in town. It was fun enough and you’d see the occasional raccoon. In that time it was legal to busk up and down State Street. Folks would travel through from college town to college town and play guitar on the street just to make food and cigarette money.

In the course of my nocturnal walks, I came across a fellow named David that was playing. He was sort of rhythmically challenged, but he knew a lot of songs. He played “Would You Lay with Me in a Field of Stone”.  He credited Tanya Tucker as the author. I spoke up from a group of a few and said “That song was written by David Allan Coe”…sort of echoing what was on the a-side of that release (You Never Even Call Me By My Name….John Prine and Steve Goodman).  I suppose that was sort of egotistical, but as a child of Nashville and Muscle Shoals I felt it my duty to share my knowledge.

The man did not take umbrage. Rather the next week, he paused in his playing as I was passing by and said “You were right!” and asked if I would look after his guitar and loot while he went around the corner to take care of other business. I picked up his guitar and played a Guy Clark song and probably a John Prine song ( at that time, that was my entire repertoire). When David came back I had a few dollars extra for him.

That started a relationship that lasted a while. David lived out of the back of his truck and looked after his Mom on their old family farm. He gave me the motivation to explore my ability to perform in front of people, and I gave him somebody to trust if he needed to take a break.  Several times, going out to dinner with friends from school,  I’d stop and spell David, and that would freak out my rather staid schoolmates.

Never knew David that well, but he would lend me LP’s with his name scrawled on them.  They were all worth listening to and obviously cherished items. He turned me on to a guitar player named Dan Crary, a really cool flatpicker.

I have never had stage fright since then; that is an obsolete response for me. I don’t play music for a living. But I still get a little hormonal hangover after the fact.  Even after doing something like giving a public talk or teaching a class. Anyway, there is no fear beforehand, but after the fact it is like a dose of vodka and espresso.

Years later when I visited the same city center again, David was still playing on the streets. He greeted me as if I’d just been gone ten minutes. I had fun playing his guitar again.

It is good just to wander sometimes.



A Ray of Sunshine

Around about 1978 there was a billboard on the outskirts of xxxxx TN welcoming visitors to the town. It read


Welcome to xxxxxx!
Home of Sheriff Buford Pusser
Governor Ray Blanton
And 1375 Happy People!!!


That sign was a continual source of amusement to pals that would sometimes visit the area to hike around the battlefield at nearby Shiloh.

There is not much reason to talk about either of those characters above except to note that they were both products of a culture (the so-called State Line Gang along the Tennessee- Mississippi border) that involved a lot of corruption centered around enforcing debt collection from moonshining, prostitution, and gambling.

You’ve probably seen a few of the advertisements for the fictionalized Buford Hayse Pusser films…they are basically just revenge flicks with lots of action. The story about Governor Blanton (some kind of remnant of the Dixiecrats) was made available in the film Marie nominally about an administrator that got caught up in the illegal schemes of the governor to sell off pardons, paroles, liquor licenses, and other state assets for personal gain.

At the end of the Blanton term, the governor started issuing pardons willy-nilly. At that time the Supreme Court in TN decided to swear in Lamar Alexander ahead of schedule for the next term as governor.

None of this sort of crap is unique, it is older than Genesis. But when government officials start talking about pardons for associates, I routinely get perturbed.

Nonetheless, a fishing trip is upcoming. It will be fun to visit the expanse of Kentucky Lake and catch a few crappie during the long total solar eclipse. That locale is along the path of totality  a few miles north of   xxxxx  and might afford an attempt to do some convincing a la Hank Morgan (that is perhaps a little over the top).  But it will be fun to sit out on the lake during the eclipse.

Perhaps a revised Ray of Blanton Sunshine (campaign jingle from the time via Dottie West) is in order.  If you don’t do anything else, listen to the jingle. Made me mad that it was burnt into my brain. It is sort of along the lines of the soft drink jingles that were popular at the time.


Ladies’ Fingers

Two of the joys of summer are not here this year. The fickle spring freeze-thaw put a damper on the July fig harvest and the May blackberry harvest.

However, the June rains have done wonders for late season arrivals. One has to keep a diary to figure out what is normal, much as like with political clownsmanship. Nevertheless, this is my all time favorite garden blossom.


The dynamic range in the photo does not really do the blossom justice; the dark area should have a lot more detail. Perhaps if the sun were right behind the camera? But the perfect pentagons get me from time to time.


Fried okra is one of those things that I’m squeamish of in a restaurant. I don’t understand the approach to much of industrial food, but fried okra is in the top five of unsatisfactory things obtainable at chain restaurants.


So here’s a more palatable version.

  1. Obtain fresh okra (aka ladies’ fingers).
  2. Slice into ¼ to ½ inch thick specimens orthogonal to the main axis.
  3. Spread and dust with salt and toss. Let drain for a few minutes as the salt pulls out moisture.
  4. Toss with corn meal in a colander or bag or some such. Shake off excess.
  5. Fry until crisp in small batches.
  6. Drain like you would any other fried food.
  7. Dust with black pepper and cayenne.
  8. No eggs, no milk, no buttermilk…no goo.

It is that simple. And completely different form the weird gooey dough balls served in chain restaurants. The version above is like popcorn. Kids eat it without questions. It is that good.

Other than that version, gumbo is nice.

In most years I only fry once or twice, but this year may be different, as in many other respects.  But it is easy to wear out a good thing, so try in moderation.



Green Boiled Peanuts at Tire Shop

I’ve been waiting for boiled peanuts to go mainstream.  Despite our ease of travel and communication, there are still some regional cuisines.  If one starts at the Gulf Coast south of my place, one will find an abundance of oysters and mullet and then some high-end seafood as well.

As one moves north through the cultivated pines and scrub oaks, the mullet consumption dies off drastically. Oysters hang on a bit longer.

But somewhere along the line you pick up little concessions like this scattered all up and down the roads.  I don’t know how far west they exist, but as far as I can tell on the way north they start to peter out around Montgomery or Macon.

I did not grow up with mullet or peanuts, so I don’t know much about either one.  Most folks will probably guffaw a bit at reading the advice columns for catching mullet.

Peanuts apparently were discovered in South America. Championed by George Washington Carver, they became an important crop around here. I get the occasional peanut volunteer in the garden; it is kind of a joy  to raise a few. One year I think I’d like to plant a plot and just see how it goes.

But back to the topic. Eating a raw peanut puts you at risk for gastric distress.  Roasting a mature peanut takes as little as 20 minutes. Boiling a green peanut can take a few hours. Why? I still don’t know. But boiled peanuts have their fans.  Years ago you could get them in a can as far north as Chapel Hill NC.  You can still buy frozen boiled peanuts in quantity at the gas station.

So I’m thinking that there must me something weirdly addictive about these things that I don’t yet understand.

Granite Oddity

The photographs below were taken in the summer of 1965.

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Shot with a Contax IIIa. Other details long forgotten, but the film was Agfachrome, 35 mm positive. Kodachrome positives from those days have held up much better.  But Agfachrome could be faster and developed locally.

The sculpture measures 190 ft by 90 ft and is 400 ft above the base.

Recovered these photos from the closet not too long ago. Just takes some time to catalog stuff in moments when everything else is going well. But you can find several, more modern photos if you want to see how things turned out.

My first thoughts, upon seeing them, told me I had to go watch Hitchcock’s North by Northwest again.

Well, those instincts were not too far off base.

The location of the photos above is Stone Mountain, Georgia.

The same fellow that did Mount Rushmore in South Dakota was also involved with Stone Mountain: Gutzon Borglum. Borglum had difficulties completing the project that was being wackily financed and overseen by the United Daughters of the Confederacy and the Venable family.

The Venable family owned the mountain and was actively involved in the second incarnation of the KKK.

From the rebirth of the KKK in 1915 until well into the 1950’s, the mountain had been a meeting place for their oddities.

The State of Georgia bought the land in 1958 and completed the sculpture in the 1960’s. The three men in the sculpture are Stonewall Jackson, Robert E. Lee, and Jefferson Davis.

I think I first visited the place in the early 60’s as a kid. Most of the kids in the family would run to the top of the mountain on the day after a Thanksgiving family gathering.

So, although the place is kind of hideous, it has a spot in my physical memory. Also a neat geological feature. Clamors arise from time to time to remove the sculpture, but even if I don’t like it, I don’t see the point of doing even more damage.


Old Friends

I spend most mornings with coffee and a short walk. Then I do a few hours of editing numerics, and language, and graphics for other folks. I guess it’s a life I chose, but we all seem to find a path somehow. Anyway, it gives me some freedom.

I lose interest in the news periodically, and music plays all by itself for me most of the time. But you have to do something different from time to time.

One of the visual distractions that pleases me is to have a couple of bird feeders outside the office window. Most of the time it is just color and motion, but sometimes a  little physics or learning about a new species.

The gray rat snake is wicked plentiful in my habitat. I had not studied them until about 10 years ago. But they are super tree climbers. In fact, they will climb just about anything.

This is a very young one climbing on a slender rod to get at my colorful distractions.

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The feeding technique is to climb the object and sit motionless for hours. The birds know the predator is there, but they taunt the predator possibly trying to distract it from their food source. Inevitably the taunting becomes ever more daring until one bird is sacrificed for the benefit of the others. From what I’ve observed the gray rat snake does not attack with the mouth first, but rather will whip its tail up into the air and catch a bird that is within a foot or two. That’s some serious coordination. After that it is just constriction.

Another interesting feature is that these critters can extend rather rigidly over gaps of a few feet. It is kind of spooky to see; you’re left wondering where will that critter be next?

Rat snake may be appropriate as a name, but I think the preferred diet is avian. Until a couple of years ago, I did not appreciate that they would be night hunters. But I reckon a lot of life is about temperature for them. On a hot night, the light does not matter. They will seek out a birds nest; then you are left wondering is it sound or scent.

I don’t know, but I reckon it is scent. The Carolina wren will build nests in any sort of sheltered location…porches and garages and such. Where you find the wren, you find the snake…sometimes in the middle of the night.

These critters have a drab color scheme. It’s kind of standard to speculate about evolutionary advantages to one trait or another, but I think it is just that..speculation.

A king snake on the front porch will tend to make you reverse course rather suddenly; however, it is just show. So, I get color schemes but I don’t understand them.

The only macroscopic critter I revere and fear around here is the Eastern Diamondback.

Anyway, looking forward to seeing if I can convince the rat snakes to shift diet a bit to the wood rats and field mice.

But I am not a charmer.