July 1888: One year before the Paris World Fair for which it was created, Alexandre Gustave Eiffel's Tower stands one third complete. At 1,000 feet, it was eventually to become the tallest building in the world.
The original colour of the Eiffel Tower during its construction in 1888 was called 'Venetian Red' as shown in the photograph, applied in the workshop before being assembled on site. The tower has been repainted over a dozen times since in different shades ranging from a reddish brown to bronze.
Due to the increased blue sensitivity of the photographic emulsion used in the image, the sky appears much lighter and washed out, but the lack of cast shadows in the photograph suggest an overcast day.
Several paintings and picture postcards of the Exposition site were used as a reference for the background buildings, and the stonework of Port de la Bourdonnais on the Seine riverbank being constructed in the middle of the photograph are sampled from contemporary photographs.
1921: A pair of horn amplifiers at Bolling Air Field, Washington, USA. Such detectors, developed in response to the rise of military aircraft, were rendered obsolete by the arrival of radar.
The 99th Aero Squadron of the United States Army Air Service first served in World War 1 on the Western Front, and was re-designated as the 99th Corps Observation Squadron in 1921, coinciding with the unit's relocation to Bolling Air Force Base in Washington D.C.
The neo-classical building of the National War College at Fort McNair completed in 1907 in the background of this photograph still exists today.
1935: Officials ride in one of the penstock pipes of the soon-to-be-completed Hoover Dam. In the same year, the pouring of the project's concrete had concluded - a total of 3.25million cubic yards.
112 people died building the Hoover Dam.
Conveying the officials in the photograph is a section of 30ft diameter steel penstock pipe nearly three inches thick. Contemporary photographs of the Hoover Dam concrete, made with locally sourced aggregate were used as colour references, and adjusted to reflect what would have been newly poured concrete. Arizona's geology in the background remains the same as it did back in 1935.
1908: A trapper boy, one mile inside Turkey Knob Mine in Macdonald, West Virginia, photographed by Lewis Hine. The mining town of Turkey Knob had grown up 15 years before - its name derived from the wild turkeys hunted in the area. Lewis Hine, a New York City schoolteacher and sociologist, traversed America on behalf of the National Child Labor Committee - often taking pictures of child workers without the permission of their employers.
Despite the darkness, the brief explosion of colour seen in the camera flash are sourced from contemporary examples of other mines within the region.
TUTANKHAMUN BURIAL MASKS
November 1925: Tutankhamun's burial mask. Three years before, Howard Carter made his momentous discovery of the boy pharoah's lost tomb. It was to be five further years before the tomb was finally emptied.
The funerary mask of Tutankhamun was placed directly over the mummified remains of the pharaoh. The 24 pound mask is made of solid gold inlaid with blue glass and other semi-precious stones; such as carnelian, obsidian and quartz, dulled by over 3000 years of dust.
For the colour references, Carter's original inventory notes were cross referenced with the restored artefact in the Museum of Egypt, with specific details checked and provided by Egyptologists.
The black resinous material seen is a result of post-mummification combustion, whereas in other areas the linen bandages are remarkably intact.