You can make 272 anagrams from letters in zenithal (aehilntz).
First recorded in 1855-60; zenith + -al1
All round the horizon is built a black cloud-wall, but the zenithal heaven is clear.
Of the above 25 projections, 23 are conical or quasi-conical, if zenithal and perspective projections be included.
It is clear that perspective and zenithal projections are particular groups of conical projections.
It is obvious that all perspective projections are zenithal.