Category Archives: Uncategorized

Amazon Unofficial Errata, Kindle Thoughts

Amazon makes an attempt to be a one-stop shop for information about products. This increases the value of their site to consumers, making it one of the first places many think to go when they are looking to make a purchase.


OK, how about this, then. Under any book they could have an

Unofficial Errata

link that takes you to something like a forum, where people give an edition number, a page number, the existing text, and what they think is wrong with it. Maybe a fixed-in-edition field. People could respond to that post saying “no, you got it wrong” or whatever. And Like/Dislike buttons.

The publisher would probably still have their own *official* errata page. But I think Amazon could easily take over *unofficial* errata. Surely the errata forum software would not be that hard to write, given that they already have other forums.

Or heck, maybe publishers would rather Amazon take care of the official errata as well. The publisher/author could log in and “approve” errata.

So now imagine that such forums exist. If you own a Kindle, perhaps you could say that you want errata to be shown inline. The old text would be crossed out, and the errata version would be shown. Perhaps the user could select “show errata those with Likes > Dislikes” or “show only approved errata.”

Kindle Sidekick Mode?

Speaking of Kindles, Amazon’s big Kindle is way more expensive than the little one — probably a reflection of two things: lower volume, and a higher failure rate in larger display sizes. The failure rate is bound to come down, but in the meantime, how about making it possible to use a *pair* of little Kindles together in interesting ways? For example, let’s say I’m reading text that refers to a diagram; can I bring the diagram up in the other Kindle and keep reading? Or it could be a reference to a table, or a picture, or a concept in a previous chapter, or a URL, or errata, or a note I wrote, or a link *I* made to a page in another book, or whatever? Or I could be in the index or table of contents in one Kindle and whatever I selected would show up in the other Kindle? Or maybe I simply want to turn them sideways and show two synchronized pages at once, one above the other. Or maybe I want to zoom into two different spots on the same map. You could imagine a holder that looks like a book, with a Kindle on each side.

The second Kindle could be the cheaper one, at $139, or I might just be using one I borrowed from a spouse or a friend, temporarily displaying text from my book without storing it there. So for significantly less ($139 + $189 = $328) than the cost of the larger Kindle ($379) I could have a *pair* of Kindles which I could use together or separately. And when I used them together, I could do some interesting things with them, with one Kindle driving the other. If one of them broke or the battery died, well, I’d still have the other. And either separately or together they would be more portable than the big one.

I wonder whether they have thought about doing something like that…

The Kindle I Would Like

While we’re on the topic, I haven’t yet bought a Kindle. One of the main reasons for this is that I’ve heard that its support for PDF files isn’t great (as of the Kindle 3), and apparently its conversion PDF-to-Kindle conversion facility only works well with simple documents.  So since much of what I would like the Kindle for is to read PDFs, I’m holding off for now. I’d really want the following for PDF support:

  • accurate rendering
  • good page-turn performance
  • usable navigation on the page
  • the ability to recognize two-column text and flow through it naturally
  • a usable zoom facility
  • search capability
  • the choice between portrait and landscape modes
  • the ability to add annotations (highlights and text notes).

Beyond that, I’d really prefer a Kindle with a slightly larger screen. Seven inches is common for LCD readers, and for technical books with code listings and diagrams that seems like a big advantage.

In fact, one such reader, the Ematic EB101, has no network interface at all; you add books via a memory card or USB, and for that reduced functionality the price drops to $80. For me, that’s a great trade-off: I am on computers a lot, so plugging in a reader once in a while to pick up a new document is no problem.  In fact, for some work documents, I am not allowed to upload them to Amazon, as I would be required to do to read them on the Kindle; direct transfer to the device is essentially the only option.

The reason I haven’t bought that reader is that it lacks the Kindle’s highly readable screen and its battery life.  I’m hoping that the next Kindle will get closer to providing the best of both worlds.


I just discovered the enTourage Pocket eDGe — that’s the idea!

“Angels’ Wings” — a poem about death and beyond

Many years ago when a woman I knew died, I wrote this poem. I didn’t really mean to write it — it just sort of weaseled its way into my head, and I fiddled with it and decided to write it down and share it with others who knew her. Her pastor, a friend of mine, read the poem to her congregation the following Sunday.

She died fairly young, this woman, in her 30s. Nobody saw it coming. She was a sweet person, the kind of woman that everyone likes even if they aren’t particularly close to her.

Anyway, I ran across the poem while looking for something in my files, and decided to share it in the hope that it will provide comfort to someone.


Angels’ Wings


She woke one day with angels’ wings,
and cried.

“So much of life I did not live!”
she sighed.


Her broken mortal body
lay there, cold.

She held the hand,
a hand not yet grown old.


“Why have you come so soon for me,
my Lord?

I know not why you struck me
with your sword.”


She heard a voice within her head,

“You think my fetching you to me
was mean?”


“Your life on Earth was but a launch
of sorts,

on a voyage that will show you
many ports.”


“I loosed you from your moorings,
set you free,

that you could come
and sail the deeper sea.”


“It but remains
to let your body go,

and open sails
to catch the winds I blow.”


With that the voice grew silent
in her mind.

She gazed upon the body
for a time.


An understanding found her,
by and by.

She spread her wings and raised up
toward the sky.

What goes up…

I ran across this interesting graph showing the altitude, outside temperature, and inside temperature of a flight box as a balloon carried it up to about 32,000 feet and then popped. This is part of the Icarus Project, an adventurous experiment by a fellow named Robert Harrison. The graph is a treasure trove of artifacts to explain, and it is good practice for anyone interested in the sciences to try to interpret it. The comments under the graph show the thoughts of others intrigued by the graph, particularly by the rapid fall in temperature at 13:15.

Let’s start with the altitude graph, though — even that is interesting. You can clearly see where Robert turned on the instruments and then released the package a few minutes later, allowing the balloon to rise. Its ascent is very close to linear until the balloon pops and the flight box starts to fall. Notice its descent, though — at first glance it looks a little odd, convex instead of concave. Usually we expect things falling in a gravitational field to pick up speed as they fall, leading to a concave graph, but the flight box and deflated balloon quickly reach their maximum velocity and then slow down, leading to a convex graph, as the density of the air increases at lower altitudes. It looks like the flight box might have landed in a tree, from which Robert retrieved the package and turned it off.

Now let’s look at the internal and external temperatures. First take a look at the first graph on this page, which beautifully depicts the effect of altitude on temperature in earth’s atmosphere. In fact, from this graph you can clearly see why atmospheric scientists divide the atmosphere into layers. For the first 10 kilometers — about the height reached by Robert’s flight box — there is a remarkably linear drop in temperature on this graph as we get further and further away from the objects on the surface, which soak up and radiate/convect back the sun’s energy.

Back to the Icarus graph, temperature falls as the balloon rises, as expected. Not surprisingly, the exterior temperature drops faster. Then the exterior temperature mysteriously “bounces” off of 20 degrees — what could explain that? Could it be that the heater is controlled by a thermostat and came on at 12:03? If so, it looks like it is mounted close to the exterior sensor — the effect is much more dramatic on that sensor’s readings.

Then at 12:45, the temperature starts rising again in earnest, even though the air temperature is presumably still falling as the balloon continues to rise. This is likely the result of the fact that at higher altitudes the density of the air decreases — fewer collisions between air molecules and the flight box means less heat transfer out of the box, which is heated, so the exterior temperature gets closer to the interior temperature. Or again, if the heater is running close to that exterior sensor…

Then POP! — the flight box and deflated balloon begin to fall rapidly. This rapid descent means that many cold air molecules are colliding with the surface of the box, each taking heat from it. The internal temperature falls as well, but of course more slowly, as the increasingly cold exterior surface cools the air inside the box.

But as the flight box descends, the temperature of the air increases, so eventually the onslaught of air molecules becomes warmer than the exterior and the exterior starts heating up again, and for the first time the exterior sensor registers a higher temperature than the sensor in the heated interior. On the way up the exterior temperature bounced again — is that the heater turning off at 13:26?

Once the descent stopped, close to the ground, the temperatures came to match that of the surrounding air. It appears that at that point the heater was off, because the interior and exterior temperatures are about the same.

What an interesting graph! I wonder if this is how scientists feel when poring over data from probes crashing into comets…

The heat is on

On somebody asked

“Where does the heat from a burning candle originate?”

The answer talks about “the energy stored in the bonds” being released. So far so good. But what does that mean, really?

I remember being slightly dissatisfied with that answer when I took chemistry. It was a while before the answer occurred to me; when it did, I wondered why my chemistry teachers hadn’t explained it to me. (Or maybe they had, and I was asleep…)

Remember potential energy from physics? The classic example involves a weight held above the ground; it has potential energy because of its distance from the earth, the energy that was required to lift it there. When released, it falls to the ground, and part of that potential energy is converted to kinetic energy.

A more general way of thinking about that example is that two objects (in this case the earth and the weight) are attracted to each other (in this case by gravity). The farther apart they are, the more potential energy they have as a system. Bring them closer together, and some of that energy is released, converted into another form of energy.

OK now, think about molecules, say hydrogen and oxygen — two atoms in each molecule.  Look a little closer and you see protons and electrons attracting each other. What happens when the hydrogen burns, producing water, is that the atoms are rearranged in a way that reduces the average distance between proton and electron. That difference in distance corresponds to an energy difference — the energy it would take to pull the electrons out to that greater distance.

Two hydrogen atoms sharing their electrons share them equally — the average distance between proton and electron is the same. Same for the two oxygen atoms in an oxygen molecule. But when oxygen atoms and hydrogen atoms share electrons, as they do in water, the eight protons in the oxygen nucleus are able to pull the hydrogen atoms’ electrons in closer. That difference in distance between protons and electrons is a difference in potential energy, which is released as light and heat.

OK, that’s a simplification. For starters, the nuclei of atoms repel each other, and so do the electrons. But it’s at least part of the story, and it seems like a useful intuition about chemistry, about why some reactions release heat and others require that energy be added. At least my son thought so!