ten o'clock
`` Impossible . I can not leave the city now . '' `` Why not ? '' `` Because I have a capital operation to perform at ten o'clock . '' Nancy gazed at him in consternation . `` Why , Doctor , you have always said that when the Cause needed your services you would not fail ... '' `` Nor will I , when the Cause _ really _ needs me . But at present you are better equipped to carry these messages through the lines than I. '' Nancy fingered the table ornaments for a moment in silence ; then raised her troubled eyes to her listener 's face .