"Come Sit by Me" and "Homer," the two original one-act plays at Source's Main Stage, make for a curiously schizoid evening. The first is a flighty one-woman show in which Alice Roosevelt Longworth chats about this, that and everything else on her 90th birthday. The second (and better) recounts a grim encounter between Civil War photographer Mathew Brady and a distraught captain of the Union forces before and after an especially bloody battle. From tea and gossip in Longworth's house near Dupont Circle to gore and angst in the Pennsylvania cornfields -- make of the pairing what you will.

"Come Sit by Me" is a rambling, inconsequential confession by the quirky and decidedly independent daughter of president Theodore Roosevelt; its defects are only emphasized by actress Lucy Brightman, who doesn't project any particular insight into the original character of Longworth, possibly because she hasn't yet mastered all her lines. I suspect the garrulous script by Gillian Lindsay wants to paint an outrageous eccentric, but the portrait that comes through is that of a silly, self-centered old woman who prides herself on never having grown up.

Longworth takes the requisite number of potshots (at Eleanor Roosevelt, the Kennedy Center and journalists, among other targets); passes on bits and pieces of family history; and credits the assassination of President William McKinley (and her father's subsequent escalation to the presidency) to her own indulgence in black magic. There may well be a viable one-woman show in Longworth's life and idiosyncrasies; by 1980, when she died at 96, she was a Washington institution. But Brightman's stumbling performance and lines like "I was a fag hag at 11" tend to suggest this is not it.

Thomas Gibbons is on to something more substantial with "Homer," which derives its title from Brady's belief that the Civil War "is the Iliad of our nation and I am its Homer." For him, the camera is a "new eye of history," destined to change the old ways of looking at the reality and prefiguring a day when "the world will be wholly and completely visible." Captain Sutcliff (Nick Fillah) sees him otherwise -- as a cowardly profiteer, capitalizing on the war with images that may depict a dead body but cannot reveal a man's soul or his idealism.

There are two distinct temperaments here, which is how drama begins. Brady's cool, scientific faith in the new medium clashes with the anguish of the captain, who is too caught up in carnage of the moment to appreciate or even comprehend the photographer's mission. The captain will, in fact, try to sabotage Brady's efforts to photograph a gruesome corpse on the battlefield. But it seems to be Gibbons' point that there's no turning back this particular tide: The modern-day media are already in the making.

"Homer" is effective as far as it goes. Louis Dickey has directed it soberly on a spare set that uses Brady's photographs as a prelude to the action. And Andrew White's tidy performance makes Brady a properly self-absorbed and strangely elfin herald of the global village. But "Homer" remains an episode in search of a larger context. A full-length play about Brady, perhaps?

The double bill runs through March 16. Come Sit by Me and Homer, one-act plays by Gillian Lindsay and Thomas Gibbons. Directed by James S. Blythe and Louis Dickey. With Lucy Brightman, Andrew White, Nick Fillah. At the Source Theatre Main Stage through March 16.