Those marks are quite often seen on Biograph films. I believe they might have been caused by grippers pulling the frames down, but this question would best be answered by someone (Rossell, Mannoni?) who understands how the Biograph/Mutoscope projectors and viewers worked.

Stephen B

Louis

As Stephen says, these marks are common on Biograph films - virtually universal as far as I can tell. The cause seems to have been the Biograph mechanism. In order to try to get around the Edison camera patent, they designed a system that did not require sprocket wheels and perforated films. Instead, they created intermittence by having a pair of rollers, with a part cut away that pulled the film down when they met and released when the cutaways came around. It was led through quite a complex film path. I attach a clipping from Deac Rossell's "Living Pictures" where he explains this.

The trouble is, it seems this friction did rub off some of the emulsion. My guess is this was an issue for prints that repeatedly ran through the projector. I would expect that if the damage happened in the camera, this would appear as dark, rather than light areas. But someone who has worked with the materials in an archive  would know more.

For more background, here's a very interesting account from Billy Bitzer of working with the Biograph camera and D W Griffith:

https://web.archive.org/web/20041101083922/http://www.soc.org/opcam/06_sp95/mg06_biocam.html

Hope that helps

Peter Domankiewicz

@peter-domankiewicz Many thanks Peter for the clear explanation. It would indeed make sense for these spots to have been gradually created while the films were being screened, as I imagine Dickson et al. would have more proactively sought a solution if these "defects" had been present on camera negatives and prints fresh off the lab.