I found this ad (below) and I thought it was quite interesting that is sates:
"... by a turn of the handle, is adjusted for either a light or close shave."
I realize this now: if you put one of the really old blades in an old type razor, you will find that the blade is so thick that you have to really crack the handle and head to make the blade flush. Gillette had the idea that if you loosen these old razors, you can change the blade angle. You can't do this with modern thin blades though, but there you have it: adjustable razors go back as far as 1907.
"... by a turn of the handle, is adjusted for either a light or close shave."
I realize this now: if you put one of the really old blades in an old type razor, you will find that the blade is so thick that you have to really crack the handle and head to make the blade flush. Gillette had the idea that if you loosen these old razors, you can change the blade angle. You can't do this with modern thin blades though, but there you have it: adjustable razors go back as far as 1907.