Lillian Gish and Bette Davis as sisters. `The Whales of August' stars them in delicate and humane drama

``The Whales of August,'' starring Lillian Gish and Bette Davis, prompted a broad array of observations when it had its first American showings at the recent Telluride Film Festival. William K. Everson, a festival founder and noted film scholar, suggested to one audience that the drama provides Miss Gish with her most important role since ``The Night of the Hunter'' way back in 1955. He also speculated that no matter how many more roles she plays, this performance will be remembered as the greatest of her mature years.

At a seminar on international cinema, meanwhile, film professor Annette Insdorf noted how much ``The Whales of August'' differs from past movies by director Lindsay Anderson, such as the ferocious ``If ...'' and ``Britannia Hospital.'' Introducing his own film, Mr. Anderson stressed its unashamed simplicity and the joy he took in directing such legendary stars.

All these observations are to the point, and I would take most of them a step further yet. Rarely have any actresses in the Gish-Davis age group been provided with movie roles as serious and sustained as those in ``The Whales of August,'' and Anderson was right in seizing the opportunity to work with two of the most radiant stars in film history - not to mention their distinguished supporting cast, led by Vincent Price and Ann Sothern.

It's also true that ``The Whales of August'' marks a departure from Anderson's usual brand of social commentary and satire. This may not please his admirers, however. The sardonic sting that has marked most Anderson films since ``This Sporting Life'' is nowhere to be found in this gentle tale. But the ``simplicity'' that attracted him to the project seems more enervated than elegant at times.

The heroines of ``The Whales of August'' are two elderly sisters who share a quiet home on the Maine coast. Libby, played by Miss Davis, is blind and irascible; Sarah, played by Gish, is physically able, and does her best to be understanding with her difficult sibling.

Their days seem uneventful, but strains beset them from within and without. Their personalities clash in some respects, and this is aggravated by Libby's unhappiness with her blindness. Additional challenges arise when friends barge into their lives - a Russian 'emigr'e (played by Mr. Price) whose once-dignified life is growing shabbier by the day, and an old crony (played by Miss Sothern) who's nosy and noisy.

The drama of the tale arises partly from the relationships between the sisters and their neighbors. It also grows, more deeply and subtly, from the sisters' own suspicion that living together may not be the best arrangement for the rest of their lives. In small but telling ways they test each others' limits of temper and patience, often using their friends as sounding boards or surrogate targets. In the end, they tacitly recognize the unyielding strength of their affection - which, even they must admit, is strong enough to weather any storms they may churn up for each other.

The movie's charm comes largely from its lead performances. Gish is simply luminous as Sarah, the long-suffering member of the family. It's harder to assess Davis, who has been giving odd rhythms to her dialogue ever since she entered the mature phase of her career some 25 years ago. Her portrayal of Libby is eccentric but suited to the character's own oddities and can be called a firm if offbeat success.

Price is at his most insightful as the aging Russian neighbor, a fallen aristocrat who is poignantly realizing, after a lifetime of ``visiting friends,'' how unproductive his years have been. Sothern bursts with energy as the sisters' pushy chum, and Harry Carey Jr. rounds out the cast as a handyman with a sly sense of humor.

With these assets, ``The Whales of August'' might have been a glowing entertainment. And sometimes it is. What makes it seem pale and slim at other times is director Anderson's too-modest approach to David Berry's screenplay. Mr. Berry wrote the story of Sarah and Libby as a play before he wrote it as a movie, and the film is often stagy. Characters enter and exit with the calculated timing of figures in a one-set melodrama. The camera plods unimaginatively through the rooms and yards where the drama unfolds. Much of the dialogue is as stilted as Carey's ersatz New England accent.

Anderson tries to make the action ``cinematic'' by throwing in a multitude of gorgeous scenery-shots, dazzlingly photographed by Mike Fash, but these don't contribute enough variety and energy to bring the film more vigorously alive. ``The Whales of August'' is a delicate and humane drama, and its performances will go down in the history books. I'm sorry to report that it's not correspondingly original or stirring.

The film will begin its American theatrical run next week.