Monday, February 8, 2021

Survey quest

Have you ever seen one? They're everywhere. They're so ubiquitous, in fact, that you might not notice them.

Survey markers.

Many show where pipes and cables are buried. Some mark property boundaries. The one pictured above is a standard survey marker placed by the National Geodetic Survey of the United States (NGS).

Each survey marker of the NGS is paired with a file in a publicly accessible database that stores a huge amount of geographic data. Other countries have their own versions of the NGS.

Geocaching is a popular pastime worldwide. People establish a container of inexpensive souvenirs for other people to find. Geocachers take an object out and leave one in its place. The fun is in the journey - the searching and finding. There are geocaching websites on the Internet. Check them out...that just might be your next passion.

Survey markers are sorta the postage stamps of geocaching and some geocaching sites have sections about survey markers. Like stamps, they all have more or less interesting backstories on file. For instance, there is a survey marker on a step in the Colorado State Capitol in Denver that shows precisely (and I mean "precisely") where a mile above sea level is.

Last fall, I used a local survey marker as a destination for a hike. I planned to use it for an activity in one of my LabBooks. I found it by using the map search engine, here:

The marker was about two miles away on the other side of nearby Interstate 25. 

The marker is on a little concrete mound on a shoulder between an urban street in the Denver Tech Center and the Interstate. There's a stake there to indicate its position.

It was a reasonable urban hike on a nice day.

If you tap (or click) the marker on the website map, you get a link to the data file.

How much information could be attached to such a little metal plate. You'd be surprised. There is position information - latitude and longitude to five decimal places of seconds, and altitude in millimeters. There's also a detailed description of the site and the buildings and streets in the area.

If you want to know your place in the world, a survey marker will tell you.

The map also gives a link to a geocaching site:

There are survey markers associated with monuments, mountain peaks and other geological points of interest, and town squares. If you think you might be interested in benchmark hunting (that's what it's called), check out this site:

Monday, December 21, 2020


I live in an extended family and as jobs and other life situations change, responsibilities shift over time. I have recently become the chief cook and bottle washer (literally) and that isn't a complaint because I really do enjoy cooking. 

I specifically enjoy cooking because I enjoy eating good food and, if I'm cooking, it lets me ensure that there will be good food. 

The problem is that, since I retired seven years ago, others have been doing the cooking. I was a little worried that I had lost my touch but, evidently, cooking is like riding a bicycle...without the pedals, of course.

A lot of the food from my first family has come to my rescue. I didn't really carry the food of my childhood with me when I started college and moved from home but, after my parents died, I found myself going back more and more.

Southern food developed in a society where people had little time away from work to deliver extravagant meals to their families and poverty often forced them to use what they produced from their own gardens or otherwise had on hand. From humble origins, a real cuisine developed.

A popular meal here centers on smother-fried meat. I didn't specify the kind of meat because pretty much whatever you excavate from your freezer will serve.

The key idea is that gravy will cover a multitude of sins. Bad cuts of meat, over cooked main dishes, left overs? Gravy is always the answer!

Smother-frying is a multi-step process.

I start with about a pound of meat for three people. If it's a big chunk like pork loin, it needs to be cut into slabs. Chicken breasts are fine whole. With a hot skillet (about 250°) with a liberal amount of oil or grease coating the bottom, I lay out the meat and sprinkle it with seasoning (Tony Chachere's seasoning is the current favorite) and a coating of all-purpose flour (I use about a half cup flour for 2 pounds of meat, then another half cup when I flip the meat ). Then, that fries for five minutes.

The flour isn't really a batter - it will make the gravy. I just want it to absorb the flavors in the pan as the meat cooks.

After five minutes covered, I flip the meat. Add a cup of water to keep the stuff in the bottom of the pan from burning to black. Charred is good, black is bad. More seasonings and most of the rest of a cup of flour goes on the meat. Cover again for five minutes.

Flip the meat and scrape up the stuff that has stuck to the bottom of the pan. Add a little more water and let it all cook covered for a couple more minutes. You'll want water and salt (I use soy sauce for the salt) on hand for the next part).

Reduce the heat to a simmer. This is the fun part where you craft the gravy.

Scrape all the stuff off the bottom of the skillet with a spatula and start adding water and, maybe, more flour until you have a lumpy gravy. This is not a place for satiny smoothness. Work out all the big lumps. Taste the gravy occasionally and add salt and other seasonings until it tastes the way you want it.

Let it simmer until you've ready to serve it and you've got a great meal.

I like this dish because you can play with it using just about any kind of meat (fish takes a delicate touch and a lighter gravy with much less thickening, in fact eggs, instead of flour makes can interesting gravy), different seasonings and thickeners, and a vast variety of sides. In the picture above, I lined up smother-fried chicken breasts with white rice and seasoned, steamed vegetables.

Smother-frying involves a good bit of style. If you try it out, you'll find yourself automatically adjusting to the amount of heat you use, how you deglaze the pan, how much and how often you add water and seasoning... it's a method you can own.

Saturday, November 21, 2020

Do you know your north?

Heh. In the Denver area, that's easy.

That's west. (See the Rockies?)

That's east. No mountains. In fact, when you top that hill, it's plains as far as you can see...all the way to the Mississippi River, 600 miles away. They don't call the Great Plains "Great" for nothing.

Facing the Rockies, north is to your right.

But why should you care?

Let's say that you're hiking somewhere other than Denver and you suddenly realize that you don't know where you are? Even if you have a map, you have to orient the map to your surroundings and the way you do that is to point north on your map (there will be a symbol pointing north just for that reason) toward geographic north.

You could just choose a direction and start walking. Surely a straight line will bring you to a road or stream or something you can follow out.

The problem there is that humans are very bad at walking in straight lines. They're much better at circles. People have a dominant side. If they're right handed, their stronger right side tends to push them to the left.

The way to walk in a straight line is to find a landmark and walk to it. When you get there, sight back to where you came from and extend that line of sight in the direction you're going, find another landmark, and walk there. Repeat.

But it's best if you have some idea of where you're going. Do you remember a road to the east of you? Is there a town somewhere to the southwest? Your reference is north.

When you face north, east is to your right, west is to your left, and south is behind you. And the sky will always tell you where north is. 

At night, Polaris, the pole star is due north (actually, it is off by about a degree but it's good enough for navigating on land.) If you know any objects in the sky, you should know Polaris, the Big Dipper, and Orion. The Big Dipper is hard to miss because it looks very much like a...well, big dipper. The two stars in the outer edge of the dipper are called the "pointer stars" because they point straight up at Polaris.

(South of the equator, Polaris australia is a very dim star, so you have to find where it should be by following the upright of the Southern Cross.)

If you find Polaris, you've found north so just walk straight toward...oh, wait, it's night. You shouldn't be walking around in a strange forest at night. Just wait until morning and, okay, where was Polaris, again?

Well, look for moss on a tree.

Eh, that's not a reliable way to find north. Moss likes sunshine and most of the sun in the Northern Hemisphere comes in from the South so, yes, mosses like southern exposures but they grow where they can. In dense forests, you can't trust them.

So, here's one.

Set up a vertical post (what astronomers call a "gnomon" - a rod used to cast a shadow or sight some object) and, at the top of its shadow, drive another rod into the ground. In about an hour, come back and place another rod at the tip of the gnomon's shadow (it will have moved). Strike a line from the gnomon halfway between the other two rods - that points north. A line from the second rod to the third points east.

The idea is that the sun rises in the east and sets in the west, and in the northern hemisphere, the sun is to the South, so the sun's shadow points north and moves from west to east. The problem is that this method depends on when you mark the shadows.

In the picture above, a line drawn from the rod at the left to the nearest rod points due north because I placed them at solar noon (not at Daylight Savings Time noon). At solar noon the sun is due South.

If you place the rods an equal time before and after noon, this method works.

Don't know what time it is? Well, start before noon and place small markers every so often at the ends of the gnomon shadow - maybe use little rocks or stick small twigs in the ground. Where the end of the shadow is closest to the gnomon - that's solar noon. Draw a line from the gnomon to that point and you have north.

If you spend a lot of time outdoors and pay attention to where the sun is, you can get to where you can just look at the sun and tell about what time it is and where north is.

Keep in mind that, in the Southern Hemisphere, you have to look for where the southern pole star would be if you could see it, and the sun will be in the north during the day.

Monday, November 9, 2020

A universal sundial

A world globe can be used as a sundial that can tell you the time of day anywhere on Earth, time of sunrise and sunset, how the seasons work, and many other things. All you have to do is orient it in the same direction relative to the sun as the Earth. That way, it models Earth in space. Here's how you do it.

You will need a surface that can be tilted (and, possibly a clamp for the base of the globe to keep it from tilting over. Alternately, there are globes that can be tilted in respect to the base.) You will also need a mini-gnomon. A gnomon is just a vertical rod that will cast a shadow in the sun. It has to be small enough to position on the globe's surface. I used a plastic bottle cap and drove a screw through the center from underneath. (The screw should be as near a right angle to the surface of the cap as you can make it. You can test it with a carpenter's angle or even the sides of a sheet of paper.) After using a carpenter's level, or a phone app level to level the surface you will place the globe on, place the cap on the surface and mark the edge at the point north of the screw. Use a magnetic compass or a phone app but don't forget to look up the correction for true north from where you live and add or subtract it from your compass bearing. (Do an Internet search for "magnetic declination".)

With the line between the screw and the edge mark pointing north, make another mark with an erasable marker at the end of the screw's shadow from the sun.

Now, set your globe on the surface with the north pole pointing north (according to your compass with the correction to true north.). Rotate the globe until your position is on top.

Now for the fine tuning. Place the mini-gnomon pointing north directly over your position on the globe. If the sun's shadow on the globe and the sun's shadow on the Earth are oriented the same, they will both be oriented the same in space in respect to the sun, so tilt and rotate your globe until the tip of the screw's shadow touches the mark you made earlier at the shadow's tip. Your globe is now aligned.

What time is it? One way to tell is to watch your mini-gnomon to see when it's shadow is shortest - that's solar noon. During daylight savings, the local time will be an hour behind solar noon.

You can find where on the globe that it's solar noon by moving the mini-gnomon around to find the place where it's shadow is shortest. That will be a line of longitude. Knowing that every 15 degrees of longitude is an hour will allow you to calculate the time anywhere on Earth (at least, while the sun is out.)

You may have heard that the sun is directly overhead on the equator at noon each day. Try it out.

When it's solar noon where you are, place the mini-gnomon directly over your position and slide it straight down your line of longitude to the equator. Does the screw cast a shadow? Not if it's one of the two annual equinoxes. On any other day, the sun will be exactly overhead somewhere north or south of the equator.

You can easily see where sunset and sunrise is by finding the day-night divider line on your globe.

At my current time, here, sunset is slowly creeping off Africa into the Atlantic.

There is a lot you can do with the universal sundial. Can you use a thermometer to measure differences in temperature on the surface of your globe according to the angle the sun is shining on it? That's what causes the seasons.

Once you have a globe oriented, you can use a clamp or clay or some other way to freeze it in position and make a cover to keep it out of the weather. Then you can use it all year.

Thursday, October 22, 2020

Arduino Science Journal

I've commented on both Arduino and Science Journal on this blog. Now they're the same. Google has transferred Science Journal to Arduino, so, if you use Science Journal, it's time to upgrade.

I'm expecting good things in the future. Although Google has had a strong focus on education, it's sorta spread out and I've felt that the Journal hasn't grown nearly as much as it could. Arduino expresses a commitment to Science Journal and Arduino boards as an ongoing tool for learning. Hopefully we'll see exciting change in the future.

Tuesday, October 20, 2020


My dream job is "tutor". I enjoy seeing "the light go on" when someone grasps a difficult concept, such as differentiation. 

I've heard people say that calculus is hard because, unlike arithmetic, it's not intuitive. I've even heard people grudgingly say that algebra and trigonometry are intuitive. But not calculus.

Things are intuitive when we are exposed to them so much that they become second nature. We aren't exposed to fractions - we are exposed to parts of objects and fractions are the way we are taught to think about parts. Why are fractions intuitive and derivatives aren't? Derivatives are the way we learn to mathematically handle change and we are surrounded by change.

Why is, say, multiplication, intuitive? You probably know how to multiply two big numbers using long, or partial product, multiplication. You multiply one long number by each digit of the other long number and then you add the products together, but you have to position each of them just right before you add them. Why do you do that and why should you be confident that such a complicated procedure will work every time?

Is that intuitive?

Did you know that all the arithmetic you use is based on a handful of assumptions that nobody tries to prove. One is: a=a. Everything is equal to itself. That might be true in a single case, but how do we know that it's always true? I'm not at all equal to the me of five years ago, but then, I wasn't the same person five years ago that I am today. This instant, I am equal to myself.

Can you divide and always come up with whole number answers. There's a perfectly legitimate and useful way to do that and you might not remember it, but I can just about guarantee that you did it in elementary school! 

How do you know that 2+2=4, and why would you think that it is always the case? Can you prove it? We take an awful lot for granted.

Isaac Asimov was a great popularizer. Through most of his publication history, word processors didn't exist. Have you ever used a typewriter? Typewriters were what we used to create documents when I was in college. Word processors came out while I was in college. The typewriter word processors let you look at sentences you typed before you committed them to paper, but the computer programs were really cool. You could type an entire book, then go back and make corrections, change formats, and even add pictures (!!) before you printed it out. And then there were desktop publisher applications that made it all much easier and added a lot of options.

But the end result was still what I call "flat copy". The page just sat there while you read it. I still use word processors, for instance, I am typing this blog on a word processors app, Google Docs, on my cellphone. While you are reading it, it just sits there. I have embedded videos into some of the blogs, but they're still not anything you could call "interactive".

What I really enjoy using for educational materials is a spreadsheet application.

There's a link up there to the right that will take you to the download page of my other website. The page is called "Excursions". Most of the free downloads there are programs (like the statistics spreadsheet DANSYS) and their user guides, and LabBooks.

LabBooks are textbooks that are spreadsheet documents. Since they are spreadsheets, they're not flat copy. While you're reading them you can be doing other things, too.

LabBooks are lifelong projects for me. I might not live long enough to finish one, but I place them on my Excursions page when I update them. I just reposted the Mathematics LabBook. I waited until I had completed the first part of the first section. It's about the natural numbers (AKA the whole numbers) and the basis of arithmetic. All those questions I asked above? Read the Mathematics LabBook and you will understand the answers.

It has exercises you can do on the page and some buttons you can push to generate problems and get the answers. And you can do your own calculations in it.

I like to open up a concept and show how the insides work.

There are a few loose ends I need to tie up in the rest of the first section. For instance, I've been saying that I will show you how to memorize long numbers in mental calculations, and I will do that on the next sheet.

Talking about interactive documents, I would think the next wave of educational software might be virtual reality. A housemate is into VR. It makes me dizzy but I can imagine "Mister Wizard in a can." 

Thursday, October 15, 2020

Autumn trees

People are talking about going to the mountains for fall colors. I don't understand that. Back East, most of the mountains were covered by deciduous forest which blaze into color during the fall but even there, at the higher altitudes in the Blue Ridge, they turn into alpine forests of assorted evergreens. 

Here, the Rockies gain altitude quickly from east to west and become evergreens and aspen. The aspen provides patches of bright yellow and there are some colorful low shrubs, but most of the color are in the towns where many of the trees are from other parts of the world. 

The photos above are from Centennial, where the residential areas have colored up nicely. The plains host some nice fall colors where there are trees. Willows, cottonwoods, and sumacs grow along streams and produce bright yellows and reds.

The color pigments in tree leaves are associated with sugars that have been stored up in the plants. They're always there but chlorophyll, the pigment that converts sunlight, carbon dioxide and water into stored energy in the form of sugars, is more important to the tree so the green drowns out the other colors. When the Earth tilts away from the sun and trees get ready for less light and colder temperatures, the deciduous trees stop producing as much green chlorophyll before dropping the leaves altogether. Assuming that a landowner doesn't rake up the leaves for a landfill, they rot and add nutrients to the soil for future use.

Last year, I wanted to photograph the Highline Canal Trail in each season. Unfortunately, we didn't have a fall as far as the trees were concerned. To produce sugars and pigments, trees need rain and last year was a rather dry year. It suddenly became cold, the trees went brown, and the leaves came down in a matter of days. 

This year, we're getting colors, so, if you want fall colors, check out the aspens, but also visit the overlooks and view the towns like Kitteridge, Vale, Golden, and Boulder, and don't miss the cities of the plains.

How are the fall colors in your area? Do they seem to be related to the weather, and how? There are many ways to study leaf colors and, for that, I will recommend that you visit the Science Buddies website ( and search for projects concerning leaf colors.

Wednesday, September 30, 2020

Get closer: cell phone proximity detector

I like my pocket computer - I'm not crazy about my cellphone (they're the same thing.)

For one thing, I'm old and it still bothers me to overhear people's intimate conversations. It's not like tv that I can turn off. And often there's no telephone in sight. They're wearing a tiny headset. Who are they talking to? Are they talking to me? - an imaginary friend (I hear they're never unkind) - a voice in their head?

But the designers of cell phones have improved some irritating issues. When you are using your cell phone as a phone, it puts all the other apps to sleep so you aren't punching buttons on the desktop while you're talking. It senses when your face is near the faceplate.

The problem with my last phone is that, when I took my face away, it didn't wake up, so I couldn't enter numbers from the keyboard or use other apps to get information. I downloaded an app to disable the sleep mode while I talked on the phone. It was quite unreliable.

My new phone doesn't have that problem. When I get close, the apps go to sleep, and when I take my face away from the phone, the apps wake up.

But how does a cell phone know that your face is close? The answer is "proximeter". All cellphones have them. Usually the proximeter is an infrared LED and detector under the faceplate. You can find it if you have a sensor app like Physics Toolbox or Examobile's Sensors. Both access the proximeter so that you can see when it toggles on and off. Just waggle your finger around in front of the phone until you see the proximeter flip.

I can see the IR LED under the faceplate at the upper left of my phone. The LED constantly shines infrared light out and when an object moves close enough, it reflects the invisible light back to the detector which triggers the proximeter on.

I'll be using my proximeter later to measure periodic events like pendulum swings, so I wanted a more precise idea what to expect from it. It was pretty easy with an optical bench. Home Science Tools ( has an inexpensive one - basically a stand for a ruler and sliders that will carry lenses, a candle, screens, etc. It also has a sliding object, a metal pointer that can be used to form images with lenses and mirrors, or, in my case, a target that I could move toward and away from my phone. With the optical bench, I could measure the distance between the object and the proximeter. I also stuck a plastic pill bottle on the object for a larger target.

Here's my setup.

I used a gooseneck camera stand to position the phone over the ruler.

I made ten measurements with each target moving it toward the phone until the proximeter toggled on, and then away until it toggled off.

I could take the average of ten distances as the "true" distance and the differences between the measured distances and the averages as the amount of error in the measurements.

I found that, for the small target, I could rely on the proximeter to toggle at 5.5 cm ± 0.8 cm. To get it to toggle off, I had to back off to 6.49 cm ± 1 cm. For the large target, the proximeter would toggle on at 4.63 cm ± 1 cm and would toggle off at 6.62 cm ± 1.6 cm.

I was a little surprised that I had to bring the large target closer to get the proximeter to toggle. I assume that the smaller, metal target reflected the infrared light better than the large, white, plastic target.

The errors in the readings behaved. If I added them up, the sum was 0 which means that they were random and followed a normal (or, at least, symmetrical) distribution. So, I can reduce errors in measurements with the proximeter by taking multiple readings and averaging them.

Notice that I had to back off further than I had to approach to make the proximeter toggle. Many control systems show that kind of behavior; it's called hysteresis. If the heat in your house goes above a certain level, your air conditioner will come on, but to make it stop, the temperature has to fall considerably below that level. If the cutoff and cut-on temperatures were the same, the air conditioner would just flip off and on all day.

You can roughly determine how near and far away from your phone you have to move to trigger the proximeter by just moving your hand in front of it, but if you want to use it as a precise instrument, you need to use a set up similar to mine that allows you to make actual distance measurements.

Sunday, September 27, 2020

play, learning, and risk

I've told a lot of tales here and they're all true (I swear by my tattoo - movie reference there.) I've talked about being in storms, falling off mountains, and walking until I'm near collapse. I'm a lifelong learner and an adventurer and I've put myself at risk to experience new things. 

In my defense, I will say that I thoroughly educate myself about things I do before I do them. I don't take risks just to take risks. And I prepare for accidents.

Learning involves risks - risk of failure, risk that someone will make fun of you, sometimes actual physical risks. When handling chemicals, fire, or electricity, there's dangers. That's why school labs come with lots of safety instructions. Unfortunately at home, people often don't bother to learn safety tips.

I have often lamented the disappearance of "real" chemistry sets and other science kits. But they seem to be coming back. It's true that there were many things in those old kits that would not even be allowed in children's toys today - including mercury and asbestos. I played with arsenic and explosives. But I'm pleased to see that modern kits like the ones produced by Thames and Cosmos, and Elenco provide lots of safety information.

Still, it's up to folks at home to safeguard their homes if they are going to allow risky play and studies...and there is plenty of research that indicates that we can easily err to one side or the other - challenges or safety (Norton, C., J. Nixon, and J. R. Sibert. 2004. Playground Injuries to Children. Archives of Disease in Childhood. (Bond, Michael (2020) From Here to There: The Art and Science of Finding and Losing Our Way. The Belknap Press. Cambridge, MA. Esp. Chapter 2: Right to Roam) (Tierney, John (July 18, 2011) Can a Playground Be Too Safe? New York Times Reports.) Many studies seek a happy playgrounds that are also challenging.

I want to thank Me. Colleen Stewart for the following safety resources.

And Ms. Stewart's website is:

Part of learning is learning to learn. Learn to be safe in learning. Here is your home safety library.

Tuesday, August 18, 2020

Rocks, smoke, and chipmunks

It's good to be back on some serious trails again. Badger and I hiked up Independence Peak, in Pence Park, South of Bear Creek and Kitteridge, last week. It was more demanding than Panorama Point being a little further, about a hundred feet more elevation gain, and fewer switchbacks. Still, there were a lot of people out and, if you've been reading this blog, you know that I consider that a plus.

If you're on the Eastern Slope of the Rocky Mountains, you might have noticed a more-golden-than-usual sun lately. When I wrote about sky colors, I neglected to mention that some of the most beautiful (and weird) displays are caused by things you don't want in your lungs. If you've ever seen any of the images from Mars, that sky is the opposite of ours - red during the day and bluish at sunrise and sunset. NASA thinks it has to do with Mars dust, which has magnetite (basically rust) in it.

I sorta felt like I was back in the Great Smoky Mountains.

The forest fires causing this is almost 400 kilometers (over 240 miles) away, but the prevailing winds are from west to east here. I've read that much of the topsoil in Brazil is blown across the Atlantic from the Sahara Desert in northern Africa.

I remember a fire in the Okefenokee Swamp in Georgia that made Selma, Alabama look like the woods just outside town were burning.

The Smokies in the Appalachian Mountains were known to be smokey long before Europeans moved in. The valleys and hollows created natural channels that captured and held aerosols from campfires and natural forest fires all over the East. With industrialization, acid rain from nearby Copperhill, Tennessee became a serious problem.

The stars of this trip are these fellas.

Chipmunks were all over the rocks and they seem to have no fear of humans.

How does the wildlife in your area behave around humans? Do wind patterns there collect smoke, dust, or pollution, or do they clear them out? How?