With a slightly chilled breeze ushering away the night sky, an estimated 300 people were at the Washington Monument to open the fifth annual Prayer Vigil for the Earth. Thirty hours of prayer amid the nation's monuments end today at noon. Begun in 1993 by two groups called The Circle and the Wittenberg Center for Alternative Resources, the vigil prays to make the Earth well again--to cure disease, clean the rivers, make the air breathable. Until this year, the ceremony used only American Indian traditions. But this time, organizers expanded the vigil to other cultures and religions.