The roof in that N&W pic is a Climax radial, by Chicago-Cleveland (the various Viking roofs are their best-known product). The large clamps on the seam caps are characteristic of C-C's all-steel roofs.

If you're thinking of the Cambre radial roof used on the last X29s, C&O and NKP's ARA 1932 boxes, and DT&I's USRA ds rebuilds, that one dates back to at least circa 1915 or so (though the early applications had diagonal ridges in the panels).

David Thompson