LAST WEEK in London there was a ceremony to launch the reconstruction of Shakespeare's Globe Theater on its ancient site beside the Thames. Prince Philip and other dignitaries attended, and an actor read the prologue to "Henry V," in which Shakespeare voices his doubts about the adequacy of his rough, circular theater -- "this wooden O" -- for presenting such a spectacle. He begs the audience to

pardon, gentles all,

The flat unraised spirits that have dared

On this unworthy scaffold to bring forth

So great an object

Sam Wanamaker, the moving spirit behind the new Globe, has been hampered by no such doubts. The 68-year-old American actor and director has spent much of his adult life pursuing his dream of resurrecting Shakespeare's theater on its old site in what is now a dreary warehouse district.

Over the years he has raised money from people all over the world (and must raise a great deal more to achieve the hoped-for opening of the Globe by 1992), has battled the local borough government (a zoning dispute enlivened by Labor Party complaints that the project was "elitist") and has countered complaints from some Britons that he was trying to create a sort of Shakespearean Disneyland (the project calls for a museum as well as the theater accommodating 1,500 people.)

Now, at the moment of his triumph, he has run into yet another dispute. A debate has erupted in British newspapers about the authenticity of the 24-sided design of the new Globe. One historian, making the case for a hexagonal design, calls the 24-sided one "a figment, a modern artifact based on a misunderstanding of Elizabethan timber construction methods." Those who have worked with Mr. Wanamaker and his organization, the Shakespeare Globe Trust, say more than 200 scholars were consulted before the present design was settled on.

This is the kind of debate that could render one's spirits pretty flat and unraised. Fortunately, it seems not to have affected either Mr. Wanamaker's determination to proceed or his mystical devotion to Shakespeare and to that spot of land beside the Thames, a place of which he said last week, "It encompasses the spirit of the theater. . . . You have an epic feeling here." The audiences that will fill the Globe will likely share that feeling, and if some day further research into Elizabethan timber construction methods proves its design to be wrong, it can be remedied by posting a warning at the entrance -- one that might also preface the better part of Shakespeare's so-called historical dramas:

"Not too authentic, but a lot of fun."