"Q.E.D.," in the new, limited-run CBS series of the same name, stands for Quentin E. Deverill, the lead character, as well as the traditional Latin "quod erat demonstrandum," paraphrased in the premiere as, "quite easily done" or, "as any fool can plainly see."

The one-hour comic adventure series, at 8 tonight on Channel 9, was produced in England by John Hawkesworth, who helped shepherd "Upstairs, Downstairs" and "The Duchess of Duke Street" onto television. But this new program, produced--condescendingly, perhaps--for American Tee-Hee, comes off as a too-cute cross between "The Avengers" and "Wild Wild West."

Set in the England of 1912, "Q.E.D." offers Sam Waterston as Deverill, a pompous and abrasive quack of all trades whose life is a series of madcap scrapes. In the premiere, he falls in with a young woman whose brother has disappeared at sea and with a pack of Germans who corroborate with the evil Dr. Kilkiss, a Moriarty to Deverill's Holmes. Kilkiss takes credit for, among other calamities, the sinking of the Titanic.

There are chases and tumbles and gadgets, and an escape in a pretty balloon, but the script by Robert Schlitt, under Don Sharp's direction, is so facetiously precious that there is nothing in the program to warm up to. The trappings are all quite handsome, and anything in prime time not produced on a tacky Hollywood back lot is to be appreciated, but once you get past the trappings, you may feel just plain trapped. Few things are more leaden than failed larks.