The call for "Author, Author!" can yield a complicated response: How do you define the writer of a book or poem or other piece of literature? Is writing truly a solo activity? What about outside influence, and editors? What about writing in tandem?

A new book by a University of Rochester associate professor of English challenges our ideas of authorship by exploring the works of pairs of women writers and of mediums who transcribed for otherworldly sources in the 19th and early 20th centuries.

In Writing Double (Cornell University Press, $40 hardcover, $18.95 paperback), the first full-length treatment of women's literary partnerships, English department chair Bette London shows how collaborative undertakings and alternative writing practices enabled women to become professional authors in an era when a literary career was often an elusive objective for them.

In some cases, women writing as a pair would adopt the name of a man. Katherine Bradley and her niece Edith Cooper, for example, published their poetry as "Michael Field," feeling they had to use a male pseudonym to gain legitimacy for their work. In their case, however, Michael Field's popularity declined once the identity of the actual writers was discovered.

In other instances, the authors' identity would only be mildly masked. Cousins Edith Somerville and Violet Martin established themselves in Irish fiction under the names "E. Œ. Somerville and Martin Ross." They published 16 books between 1889 and 1915, and even after Ross's death in 1915, another 14 books appeared under their dual name.

Whether using a single or dual identity, all the authors insisted on the seamlessness of their writing. Somerville and Ross, who talked out all their books together, emphatically maintained that it simply didn't matter "which hand held the pen"; every sentence, indeed every word, was a co-production. Bradley and Cooper, who retired to separate rooms to write after discussing their work with each other, claimed they were unable to distinguish their individual passages when they read the final product. Even the handwriting of collaborators often came to resemble each other's.

"Women didn't want to divide or parcel out their work according to who wrote what," London explains.

Automatic writing-in which a medium in a trance writes down words coming from a dead literary or historical figure-further complicates notions of authorship, according to London. Sometimes, two mediums would work together. Sometimes, a medium would use a ouija board and an assistant would write the words, adding additional layers of transcription. Among the practitioners of alternative writing was Georgie Yeats, wife of poet W.B. Yeats.

"To what degree do you have the right to claim authorship if you're the medium getting the message?" London notes. "In what precise act do you locate authorship? If you write the words on the page, does that make you the author?"

London also examines the Brontë juvenilia, the works that the Brontë sisters-Anne, Charlotte, and Emily-and their brother Branwell wrote among themselves not for publication, but for their own entertainment. The siblings created miniature books, put together magazines with book reviews, illustrations, and criticism, and composed fantasy serial stories well into their adulthood.

"The model of the solitary author is largely an invention of the romantic era and was institutionalized in the 19th century," says London. "But we're beginning to acknowledge other influences, such as how an editor affects what actually gets published, or the influence of friends and family on an author's writing. Especially now, with the boon in electronic publication on the Internet, we are much more aware of the possibilities of multiple authorship."