In September 2009, the Lehigh University Library loaned me a Kindle 1 for evaluation purposes. I used it for both light reading and experimented with it in reading a mathematics text. The mathematics text I chose was my book Galois Theory, so this was a book whose contents I was intimately familiar with, and hence I was well able to judge Kindle's performance in rendering it.

Light Reading

For light reading, the overall reading experience on a Kindle is roughly comparable to that of a book, with some pluses and some minuses.

Pluses:   The Kindle font is attractive and print is crisp and easily readable, even in bright sunlight. The font size is adjustable. (I read it on level 5 of 6.) I think the readability is the strongest point of Kindle, and I think it is potentially a godsend for elder people or people with vision problems (although perhaps even larger fonts would be desirable). The most important Kindle controls--book selection and font size selection--have dedicated buttons. Kindle remembers the last page you have read when you shut it off and opens to it when turn it on again. Kindle lays flat, while books usually do not. It is lightweight and handy, and, so is particularly good for travelers. I tend to travel heavy, with lots of reading matter, and books take up lots of space and weight, and a Kindle would obviate this problem.

I thought the frequency of page changes with a large font would bother me, but that was only a small annoyance. Still, if I were to use an electronic book reader, I would prefer one with a larger screen, and there is a new Kindle DX, which has one. If I were to buy a Kindle, it would be the DX, although that is considerably more expensive. (On the other hand, I often like to walk around with a book stuck into my pocket, and a criterion for buying jackets is that they have large square pockets that are big enough to hold books. A Kindle 1 would fit in such a jacket pocket but a Kindle DX would certainly not.)

Minuses:   It is impossible to do anything like browsing through a book. Amazon realized that page numbers are meaningless for Kindle, as you can resize the font, so instead they have "locations". But most aspects of this are poorly thought out. It's almost impossible to tell how long a book is. The dots at the bottom of a table of contents entry are not very informative. You can bring up a "go to location" screen which will tell you the total length, but that's a frustrating extra step to have to go through. In a book that consists of a series of short stories, say, the table of contents gives the name of each, and a link to jump to the start of each, but no location numbers, so you can't tell how long each is, without jumping to the start of each and noting the location, something much too frustrating to do. (And then you'd have to remember it.) It would be much better if this information were listed in the table of contents. For a novel, say, there is no easy way to find out the lengths of the individual chapters, something you can easily do by flipping the pages of a book. (Often, when reading, I like to know how long a chapter is or how near the end of one I am, to establish convenient break points for my reading.) Also, there is no way to toggle between two pages. These drawbacks are really serious ones for me. As a minor point, it would be nice to have a lock button for the controls. It's too easy to hit "next page" when you're putting the Kindle down, picking it up, etc.

Serious reading

Reading mathematics

Kindle simply cannot get mathematics to display properly. This completely disqualifies it for use in reading mathematical texts.

Let me list (some of) Kindle's shortcomings in ascending order of severity, ranging from annoying through disconcerting through making the device impossible to use.

1. As I noted in my previous comments, there is no reasonable way to jump between pages (or "locations"). Thus if you're reading the proof of Theorem 4.3.5, and the proof says "By Theorem 2.3.7 we know that ...", there is no reasonable way of looking up Theorem 2.3.7 and then returning to Theorem 4.3.5.
2. Mathematics is carefully typeset, with lots of attention paid to line breaks, margins, display of formulas, line and page breaks, etc.
1. Kindle attempts to have even right margins, inserting spaces between words as necessary. But it inserts spaces in the middle of mathematical expressions, too. For example, a common construction in mathematics is f(x). Kindle will sometimes set this as f(x) (correct) but also sometimes as f(x ) (bad) or f    (x) (worse).
2. Kindle breaks lines in the middle of mathematical formulas when that is logically incorrect. For example, f(x) can never logically be broken up, but Kindle will sometimes end a line with f and begin the next line with (x), or end a line with f( and begin the next line with x), or end a line with f(x and begin the next line with ).
3. Kindle knows that it doesn't know how to break up certain very long displayed formulas. In order to get them to fit on a single line, it displays them in a very small font. When you resize the text on Kindle to a larger font, these equations stay in a small font.
4. Subscripts and superscripts are often difficult to read, even at larger font sizes.
3. Kindle doesn't know how to handle many kinds of mathematical expressions properly. It simply gets them wrong, making the text nonsense. Here are some examples:
   1. At one point in the text, I consider two related but distinct things. As is common practice, I denote them by similar symbols. One is denoted d, and the other is denoted d-tilde (with the tilde over the d). Kindle can't handle this, and drops the tilde, denoting them both by d.
   2. The cube root of 2 is denoted by a small 3 to the left of the root sign, then the root sign, which extends over the 2. Kindle sometimes can't handle this, and instead puts the 3 somewhere to the right of the root sign, or does not display the 2.
   3. Often one uses summations in mathematics, which involve a construction i=1 as a subscript. Kindle can't handle this, instead writing i- (not i-1, just i-).
   4. There are other instances where Kindle can't properly handle subscripts and superscripts, and moves them to locations on the screen that have no connection to where they should be and are in the printed text.
   5. There are times when Kindle can't handle a symbol, and deals with this problem by simply deleting it.
   6. Sometimes Kindle gets so confused by mathematics that it garbles several lines, making them unintelligible.

Summary

The drawbacks for using a Kindle to read mathematics are far more serious. Certainly it is already possible to display mathematics properly on a screen. In fact it is not only possible, it is also routinely done. All of us are quite familiar with reading pdf files on computer monitors, and they render mathematics perfectly.

Of course, technology is in a rapid state of development. I dated my report September 2009, and undoubtedly by September 2029, probably by September 2019, and possibly even by September 2014, the deficiencies in a Kindle will be remedied. (I should point out that by now there are a number of different competing ebook readers on the market, and I have not tried the others. But I rather doubt the others are so much better in this regard.) Thus at some point in the future, ebook readers will be up to the job of properly rendering mathematics, and will be able to be used for, and indeed will be routinely used for, reading mathematics. But that day is not here yet.