Builders at the Sheshan Observatory

Sorting photos in preparation for exhibitions, I came across these two snapshots. One is taken 2004 and shows workers doing maintenance work at the Sheshan Observatory. When they saw me climbing around the roof with a camera, they posed for a photo, as if they knew (they didn't) there is a similar photo dated 1899 which is hanging in the Observatory Museum, literally below their feet.

 Builders at the Sheshan Observatory, as seen in 2004.

Builders at the Sheshan Observatory, as seen in 2004.

 A picture of builders of the Sheshan Observatory from 1899, as seen in the Observatory museum in 2004.

A picture of builders of the Sheshan Observatory from 1899, as seen in the Observatory museum in 2004.