You can find the book here or here.
I think I would advise not reading this book. You can get a better idea of George's philosophy here. If you look at the list of notable Georgists at that link, you'll see why I was tempted to read the book. I hope that the people listed were attracted to the general idea of a single-tax on land (a fine, defensible position that I think may be a decent idea and is certainly an idea worth giving a shot somewhere) but not attracted to all of George's conclusions in this book.
The book goes through a lot of discussion to define rent, wages and interest. It then goes on to suggest that it has demonstrated that "the speculative advance in land values cuts down the earnings of labor and capital and checks production" and further that "this is the main cause of those periodical industrial depressions to which every civilised country, and all civilised countries together, seem increasingly liable." It's a bit frusterating to have spend so much time reading a book up to that point that this sentence was written and then read this sentence and realize that "speculative" was not defined and the author has not shown any data to indicate that land values have increased (it's my understanding that they haven't increased much for very long periods of time).
We get more strange statements like, "Free trade has enormously increased the wealth of Great Britain, without lessening pauperism. It has simply increased rent." I don't think that's true (increases in rent could not possibly have captured 100% of the benefits from free trade), but it's certainly an empirical claim yet it has no empirical support – it also defies common sense, so support would be nice. Or later, George asks "how can there by over-production" when "the great masses of men want more wealth than they can get" – well, what if we build 100 million houses in Cheyenne, Wyoming? Still not possible to have over-produced? George seems unable to grasp the idea that all production is not necessarily wealth creating or that a good today is worth more than the same good a year from now.
If want good economic theory, reasoned-out from the ground up, read Professor Rothbard, not this book.
Still, it's possible George has unwittingly backed his way into a good idea without have good means. Rothbard deals with George here and in doing so, does a good job setting out the main tenet of the Georgist proposal:
Single taxers [Georgists] do not deny that land is improved by man; forests are cleared, soil is tilled, houses and factories are built. But they would separate the economic value of the improvements from the basic, or “site,” value of the original land. The former would continue to be owned by private owners; the latter would accrue to “society”—that is, to society’s representative, the government. Rather than nationalize land outright, the single taxers would levy a 100 percent tax on the annual land rent—the annual income from the site—which amounts to the same thing as outright nationalization.
[. . .]
Almost everyone would agree that the abolition of all the other taxes would lift a great blight from the energies of the people. But Georgists generally go beyond this to contend that their single tax would not harm production—since the tax is only levied on the basic site and not on the man-made improvements. In fact, they assert the
single tax will spur production; it will penalize idle land and force landowners to develop their property in order to lower their tax burden.
I think Rothbard does a very good job showing why this idea won't work. But, if we have to have some form of tax, Goerge's suggestion that the "original value" of land be taxed (what exactly that value is is unclear) is a decent idea in theory. I suppose I can see why it has so much support among those who want a smaller state, but still want a state. I think Rothbard's objections would need to be answered before I would jump on the Georgist bandwagon (with all three other people onboard).