Tag Archives: navigation

Copper and Tin

Phoenician trade routes

Speaking of copper, let’s take a minute to appreciate that around the Mediterranean, people had stopped making weapons and tools out of stone and had switched over to copper. There was lots of copper to be mined in Cyprus (pronounced KI-proos). You dig up rocks that have copper ore in them and heat ‘em in a blast furnace until the metal oozes out. Copper is a whole lot easier to make things out of than stone. Its only drawback: it’s not the hardest metal and copper blades need to be sharpened constantly. Copper is soft enough that kids put pennies on railroad tracks and a train’s wheels will smoosh ‘em out. YOU MUST NEVER DO THIS.

The Phoenicians were zipping all around the Mediterranean Sea, buying and selling stuff. Eventually one of those sea-captains got brave enough to head out into the Atlantic Ocean and up north to the British Isles. You know what kind of metal they mine in southern England? Tin. So the Phoenicians brought tin back to the Mediterranean and some genius discovered if you combine molten tin and molten copper you get a new, stronger alloy—bronze. That discovery kicked off the Bronze Age.


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Happy new year! Well, we let that Rosetta Stone story take us a few thousand years ahead of our timeline. So, we’re going back to roughly 1500 bc., leaving Egypt and hieroglyphics behind so we can move along to the Phoenicians.

Phoenicians were seafaring-trading people who lived in what is now Lebanon, Syria and northern Israel on the eastern shore of the Mediterranean Sea. There wasn’t a country called Phoenicia, exactly—it was more like a federation or league of cities: Tyre, Byblos, Sidon.

The Phoenicians traded with other people around the Mediterranean Sea and beyond. The city of Byblos did a big business trading in papyrus and books. The Phoenicians sold expensive purple cloth (they got purple dye from squishing murex mollusks—ew). What drove the Phoenician economy wasn’t so much the production of goods, but buying and selling goods in the free market. You buy papyrus in Byblos where they have lots of it and it’s not so expensive, take that papyrus to somewhere—maybe Cyprus—where they don’t have very much papyrus and they’ll pay much more than it cost you. You use the profit to buy copper for cheap, because Cyprus has lots of copper. You put that copper aboard your ship and take it where they’ll pay you well for it. Buy low, sell high, gang.


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Just a second

Before I got side-tracked into digital clocks and watches, we were talking about satellites and the Global Positioning System. I mentioned that the satellites that send us navigational signals need to have an incredibly accurate clock aboard. Even a second’s difference in time between satellites’ clocks would change significantly your GPS data—and give you the wrong location.

So you’re thinking, “Well, Manders, those quartz crystal clocks lose or gain only 15 seconds a month. That seems pretty accurate to me. How you gonna improve on a system that measures 32,768 oscillations per second? How you gonna do that? How?”

To which I reply, with a rueful smile, “My friend, there is another clock yet to come, whose sandals the quartz crystal clock isn’t fit to lace. I speak of a clock that loses only one second every 100 million years!”


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Satellites and hamster balls

Satellites are useful for a whole bunch of purposes: talking on your cell phone; keeping an eye on the weather; broadcasting television and radio stations; seeing what your enemy is up to in times of war; communicating with people when there’s an emergency…but you probably guessed why I decided to talk about satellites.

Satellites serve the same purpose the stars did for Galileo and Maskelyne. They give you information you need to find your location on Earth. Satellites communicate with the Global Positioning System (GPS) on your phone or in the car. They constantly send out 2 bits of information: time and distance.

Most satellites orbit fairly close to the Earth, like 11,000 miles above its surface. When a satellite sends out information, its range is like a sphere—the satellite in its sphere is like a hamster in a hamster-ball.

Well, maybe not exactly, but you get the idea.

These spheres overlap. In fact, we want 3 or 4 satellite spheres to overlap. If you’re looking at your GPS device, satellites are telling it when you’re within their spheres.

So if you’re in the overlap of 2 spheres, you have a general idea where you are.

A third sphere makes that overlap even smaller, right? The smaller the overlap, the more accurately you know your position.

Then there’s a fourth sphere: Earth. You’re inside that overlap, and on the surface of the Earth.


trilateration noun

: the measurement of the lengths of the three sides of a series of touching or overlapping triangles on the earth’s surface for the determination of the relative position of points by geometrical means (as in geodesy, map making, and surveying)

triangulation noun

1 : the measurement of the elements necessary to determine the network of triangles into which any part of the earth’s surface is divided in surveying broadly : any similar trigonometric operation for finding a position or location by means of bearings from two fixed points a known distance apart

While the satellites are telling your GPS device where they are, they’re also zipping along at hundreds of miles an hour. Their positions change from second to second. All 3, 4 or 5 satellites need to tell you their positions at the exact same moment or it doesn’t work. They need a clock that’s even more accurate than Harrison’s chronometer.

https://thesciencegeek.org/2017/01/29/gps/                                                               mmmmmmmm


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Robert Fulton was a portrait artist who had the good sense to get out of the art business and into something that made money.

American portrait artist and inventor Robert Fulton was fascinated with the possibilities of steam power. He had acquired some political and financial backing—and an exclusive license to run steamboats on the Hudson River. After designing a steam-driven submarine, he came up with a steamboat design.

“Fulton had immense success with his steamboat Clermont in traveling the 150 miles of the Hudson River from New York City to Albany in just over 30 hours. Fulton recognized the economic potential of using steamboats to move people and goods up and down the Mississippi and in 1811 the New Orleans became the first steamboat on the mighty river thus ushering in a new era of river transportation and a romantic period defined by sidewheelers and sternwheelers.”

Just as we saw with the opening of the Erie Canal, farmers and small businesses suddenly had an affordable way to get their goods to a big market like New Orleans—or from there to the rest of the world.

They built ’em even bigger than this.

If you want the real flavor of steamboating in its heyday, you can read Mark Twain’s Life on the Mississippi here: https://www.gutenberg.org/files/245/245-h/245-h.htm
What a book! Young Sam Clemens is taught to pilot a riverboat by the master, Mr Bixby. He encounters all the characters of that time and place, because literally every class of people rode the riverboat.

You can still take a cruise aboard a steamship today: https://www.steamboatnatchez.com/
or build a scale model of the Clermont: https://www.youtube.com/watch?v=et3ZgVyi968
whose gear train really works: https://www.youtube.com/watch?v=bAVLH23qZcA

History of Steamboats on the Mississippi River


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Swimming upstream

By now I’m sure you’ve spotted the pattern: there’s a situation where people struggle to get from Point A to Point B, and some tinkerer comes along and says, “I bet I could make those people’s lives easier.” We saw how Watt’s steam engine turned a wheel to pump water out of a mine. Trevithick developed that idea into a steam locomotive to haul carts of coal. Stephenson improved the locomotive to move cars full of people along rails made of Bessemer steel.

In Great Britain and the United States, inventors worked on the problem of moving a vessel in water. Just like a locomotive, a steam engine would pump a piston to turn a wheel. This time the wheel had paddles and was mounted on either the stern or the sides of a boat.

John Fitch proposed a design with banks of oars, like an Indian war canoe.

John Fitch and James Rumsey designed steam-powered boats that operated on the Delaware River between Philadelphia and New Jersey. In Scotland, William Symington designed a boat for towing on the Forth and Clyde Canal. In 1801 his steamboat the Charlotte Dundas ran successfully upstream on the Carron River. The Mississippi is a big river with a powerful current. It would take a powerful engine to move a boat against it.


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Mister Midshipman Hornblower

C.S. Forester’s character, the 19th-century British Royal Navy officer Horatio Hornblower excelled at navigation because he was a math whiz. This got him in trouble as a young midshipman when he showed up a big dumb bully who couldn’t figure out how to work a sextant. https://hornblower.fandom.com/wiki/Sextant
A must-read—https://www.goodreads.com/book/show/84748.Mr_Midshipman_Hornblower

The sextant

The sextant is an instrument used to determine latitude and longitude. It was invented by Edmond Halley or John Hadley or Thomas Godfrey based on Isaac Newton’s ideas. You use a sextant to measure how far above the horizon the Sun is at noon (or how high Polaris is at night).

I’ve talked about finding your latitude or longitude by measuring the angle between a line from you to the moon and a line from you to a star. How do you do that?

Sailors have been using a sextant for centuries. Isaac Newton dreamed up the idea, then Edmond Halley built one in 1692. Several refinements were made around 1730, until we finally got the good old sextant you see people using in the movies with wooden ships and guys wearing wigs. A sextant is like an astrolabe—you sight something familiar in the sky, like a star, by lining it up along a sighter or pointer or alidade. Then you mark the alidade’s position on the frame and use that information to find your location.

Instead of an alidade the sextant has a telescope you look through. Then you find both the object (usually the Sun) and its reflection in the mirror. There are 2 mirrors facing each other and smoked lenses so you don’t fry your eyeballs. One mirror is half mirror/half glass so you can see both images at the same time. You bring the image of the Sun down to the horizon by moving the arm on the sextant and—oh, who am I kidding? Do you think I know what I’m talking about? What I need is a video to show how it’s done. Luckily, there are a bunch of them on the ol’ internet. Listen to these guys.

Here’s an in-depth 4-part tutorial covering everything you ever wanted to know about how to use a sextant.: https://www.youtube.com/watch?v=00ZEIZsl5xk

And a guy who doesn’t own a comb but knows what he’s talking about: https://www.youtube.com/watch?v=DrAkrgZRb9Y

The thing you have to know is: the sextant will give you a precise angle between 2 objects that you can transfer to a chart or map to get your position on Earth.


Look! Look! Here’s a cardboard sextant you can build yourself! https://www.landfallnavigation.com/cardboard-sextant-kit.html?gclid=CjwKCAjwq832BRA5EiwACvCWsWqv38smCfmUdVE5SqxRVkVJI_R0B9aN9jSb-3oaweER7b4KTm4iJhoCUbMQAvD_BwE

Here’s a plastic sextant—https://www.google.com/shopping/product/15301038968540324177?q=navigation+sextant&prds=epd:1143652539522712674,prmr:3,tpim:CKyp-dn168W22QEQ1N-msv7m0OotGMCbhR4iA1VTRCjg3sL8BTCNyIhA,pdprs:6&utm_medium=tu_image&utm_content=eid-lsjeuxoeqt&utm_campaign=134358029&gclid=CjwKCAjwztL2BRATEiwAvnALcqb-eUHLE4Y_XEM7QpPWFcXOcl2YbghLFCIcLIG1ItYYMc__vQ3_jBoCA14QAvD_BwE

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So long, and thanks for all the longitude

After 19 years of tinkering John Harrison finally worked all the bugs out of his time-piece, the marine chronometer. To prove its reliability, he took it on a voyage from England to Jamaica.

“Harrison conducted a round-trip test at sea from Britain to Jamaica through the Caribbean via the Atlantic from 1761 to 1762. The watch lost only 5.1 seconds in 81 days, reaching the level of accuracy required to receive a £20,000 reward.

But just then a rival named Nevil Maskelyne, the head of the Greenwich Observatory and a member of the Commissioners for the Discovery of the Longitude, was vying to receive the same award for his astronomical theory. Maskelyne refused to recognize Harrison’s success. To Harrison’s chagrin, he was granted only a few thousand pounds.”

Well, how do you like that? This is why Maskelyne is always cast as the villain in this story. Seems like a conflict of interest to be on the Longitude Board if you’re also a competitor for the prize. It would be quite a while before Harrison finally got his reward—and that was only because King George III* stepped in to make the Board pay up.

My pal Kathryn Lasky wrote an award-winning book about John Harrison’s story, The Man Who Made Time Travel:

Kathryn and I worked on Two Bad Pilgrims together. https://www.kathrynlasky.com/books/book/two-bad-pilgrims

* George III ruled Great Britain during the American Revolution. He was an enthusiastic friend to the Royal Navy. It was George who decreed that his sailors could toast the king’s health sitting down, because the deck-beams in the wardroom (officers’ dining room) were so low you’d likely crack your head if you stood.

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It’s 2 metals in 1!

This next part is crazy. I don’t know how Harrison dreamed up this idea. I don’t know how it’s even possible. Maybe a reader with experience in welding can help me out.*

Because metal springs are susceptible to temperature changes, which make them less reliable and accurate, Harrison invented the bimetallic strip. It is 2 metals, like steel and brass, welded together.

Did you get that? It’s possible to weld, or fuse, or something, steel and brass now. The watch’s mainspring needs always to be springy. When it’s cold, the spring becomes too stiff. When it’s hot, the spring becomes too loose. Harrison fused two metals together—steel and brass—in a spring. If the steel were too tight, the brass would keep it loose. If the brass were too loose, the steel would tighten it up. This way the spring would keep the same springiness no matter the temperature.

* This weekend I had the pleasure of consulting 2 engineers, my sister’s boyfriend Dave and my nephew Andrew. They tell me with enough heat, two different metals can be fused together. The two metals would be hammered together many times under heat until they were one. Andrew added that it’s only air molecules that keep metals from fusing together in the first place.





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