I've just finished Mary Roach's entertaining book, Spook: Science Tackles the Afterlife.

I haven't read Roach's previous book, Stiff, which explores some of the odd things that happen to cadavers after people die. Being an anthropologist, I guess I know about as much about that topic as any reasonable person could want.

But I recently saw a really interesting documentary about Harry Houdini, focusing on his other career: debunking mediums, and flipping through Spook in the bookstore, it looked like a good chance to follow up. The book didn't disappoint, and broadened beyond the spiritualism movement to describe other loopy ideas about the afterlife.

For instance, did you ever wonder why they say the soul weighs 21 grams? Roach describes the 1901 experiment, in which physician Duncan MacDougall arranged to have dying tuberculosis patients placed on a giant scale -- reasoning that if their soul belonged to the material world, the weight of the patient would drop at the moment of death. And it did by three-quarters of an ounce.

Roach follows up with a long line of other people who tried to weigh dying animals (whose souls invariably weighed less than humans, and -- unsurprisingly -- generally less than the rated accuracy of their scales). She contacts the historical archives of the Fairbanks scale company, to see if the instrument used by MacDougall was really accurate to a fifth of an ounce (it was, although the necessary modifications to hold a deathbed together with a doctor and stethoscope may have compromised its accuracy).

Early twentieth-century séances were the low-tech equivalent of today's light-and-sound shows. The medium darkened the lights (because naturally, light interferes with messages from the spirit world). Then a variety of hijinks would ensue. Often the table would mysteriously rise -- mysteriously because the medium's hands were being held by other people. A bell might ring to signal the presence of a spirit. The

The most dramatic highlight of a séance was the sudden, unexplained appearance of a mysterious substance called ectoplasm, draped over the medium. Now, if you -- like me -- are a member of the Ghostbusters generation, you probably imagine ectoplasm as a goopy, mucous-like substance that mainly plops onto people whose bodies run through a ghost.

But 1920's-era mediums didn't have Industrial Light and Magic to design their special effects. So real ectoplasm didn't generally look like mucus. It looked a lot more like damp cloth.

Because, well, generally it was damp cloth. Damp because the medium often pulled it out of her vagina. Cloth because sheep mesenchyme and other more exotic organic materials were harder to get a hold of, and were probably much less pleasant to swallow and regurgitate on demand.

Oh, yeah

Today, this sounds like the sort of stuff that wouldn't fool the Scooby Doo gang.

The first chapter struck a

Roach has what I would call a "bloggy" writing style, full of non sequiturs, set-ups for later jokes, and wonky footnotes. This may put you off -- even I found that the style sometimes wore thin. The style works best for the lighter subjects of séances, ghost hunting, and soul weighing. It seemed too glib in the sections dealing with more current research, including psychologists studying near-death experiences in cardiac patients and

Still, it helps to remind us that modern-day scientists are as almost as strange to their local cab drivers and other ordinary people as 1920's spiritualists must have seemed. And frankly, some of the modern "scientists" really are batty In my opinion, there's nothing disreputable about end-of-life research, or research into the effects of infrasound on conscious perceptions. But when people descend to talk about quantum effects on the brain and microtubules, it doesn't matter what they say, they are making it up.

In fact, I would say that quantum effects are the new ectoplasm -- try