Just to add my 2 cents to this column, hand cranked movies needed to be done at a remarkably consistent speed in order to assure consistent exposure of the film. However, skilled cameramen of the day would often change speeds during a shot, compensating for the speed change by adjusting the iris on the lens. From The Parade’s Gone By by Kevin Brownlow:
In today’s cinematography this technique is referred to as ramping, and was all the rage from about 1995 to 2005. The funny thing is, the technique pretty much disappeared with the advent of sound, not resurfacing until the film Raging Bull in 1981.