A scientist has come up with proof of something students have known for years -- chemistry lectures are boring.

In an article published in the current issue of Chemistry in Britain, a university chemistry lecturer introduced a guest lecturer to a class of 50 doctoral candidates.

Then, he and his colleagues studied variations in what he calls the HTFDR -- "head-to-floor distance ratio."

After about an hour , the average HTFDR dropped from 135cm to 121cm, said the author of the study, who preferred to remain anonymous.

The HTFDR immediately bounced back to normal when the speaker uttered the magic words: "And in conclusion . . ."