“You know, that rays of light reflected from different bodies form pictures, paint the image reflected on all polished surfaces, for example, on the retina of the eye, on water, and on glass...coat a piece of canvas with this matter, and place it in front of the object to be taken. The first effect of this cloth is similar to that of a mirror, but by means of its viscous nature the prepared canvas...retains a facsimile of the image...The canvas is then removed and deposited in a dark place. An hour later the impression is dry, and you have a picture”