When did National Geographic Magazine first publish a photograph on their cover and what was the photo ?

Well I know the first photograph was either 1889 ir 1890 and it was a photo of Herald Island. I don't know it it was the cover shot or not.

In 1959, the magazine started publishing photographs on its covers. - Wikipedia

September 1959 -- Color photographs begin to appear regularly on magazine cover. NATIONAL GEOGRAPHIC MILESTONES, National Geographic Press Release (This doesn't exactly prove that the first photograph on the cover appeared in 1959, though. However, my family subscribed to the magazine in the 1950s, and I remember that the covers had the table of contents on them.)
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AHA!

INSIDE STORY: Judge us by our covers? Yes!
Independent, The (London), Aug 1, 2005 by Chris Johns

Though I've been in the editor's chair only a few months, I've been taking photographs for the magazine for 20 years " including a few covers of my own. Here are some of my favourites.

CHRIS JOHNS, EDITOR-IN-CHIEF

AMERICAN FLAG

JULY 1959

Photography by B Anthony Stewart

For the first 70 years or so of National Geographic, choosing cover photographs was simple: there weren't any. Covers carried article titles and bylines. But in 1959, then editor Melville Bell Grosvenor had the radical notion to start running colour photos, the better to distinguish one issue from another on coffee tables around the world. His first choice, the new 49- star American flag, appeared in July of that year. Grosvenor's idea was initially opposed by tradition-bound staff " as well as by some National Geographic Society members, one of whom wrote: 'If the Lord had meant the Geographic to have a picture on the cover, He would have put one there in the first place.' The wisdom of the decision soon became obvious, however, and with or without divine guidance, images have graced the cover ever since. - FindArticles.com