He wasn't sure if it was an original drawing or an engraving, but knew his friend had financial challenges and so urged him to do something with it.

The design’s lines end abruptly on the edges of the silcrete stone, suggesting the piece was removed from a larger grindstone and that the original drawing was bigger.

One of the most ambitious, intriguing and original drawing cycles ever made, their intricacies and subtleties need to be seen at close range to be appreciated: magnifying glasses are provided.

As with other earlier reprographic processes, a translucent original drawing was placed over a sheet of the sensitized paper and exposed to light.

Finally, the architect or engineer, draftsman, checker and supervisor would sign the original drawing, making it a legal document.