Unlike all preceding theorists of cometary tail formation, Newton introduced a mechanism in which a comet's tail was produced by the convection of rarified ethereal particles which carried with them particles from the comet's upper atmosphere, which in turn became heated by reflecting of the sun's rays. The centrality of the action of the ether particles in this theory made it problematic, as a consistent theory of the ether was not then available. As a result, the theory was not wholly (...) accepted even by some of Newton's closest colleagues and disciples. This paper briefly presents Newton's theory of tail formation and examines its reception, primarily in England. I review seven accounts of cometary tail formation that were developed in a Newtonian framework and published between 1696 and 1757 by William Whiston, David Gregory, Henry Pemberton, Voltaire, Colin Maclaurin, J. T. Desaguliers, and Benjamin Martin. Newton's comet theory showed both philosophical and practical defects typical of his better known work, and I identify four major issues that early Newtonians disputed. These disagreements show that we still have much to learn about the way Newton's physics was studied in the 18th century. (shrink)