The speed
with which the paper passes through these cylinders is remarkable, from
one hundred to five hundred feet running through and over the machine in
a minute; and in some of the most recent mills the web is as wide as one
hundred and fifty-six inches (thirteen feet); this is very nearly double
the average machine width of a very few years ago, while the speed has
increased in proportionate ratio; only a few years ago the maximum speed
was from two hundred and fifty to three hundred feet per minute; at this
writing (1900) there are machines in operation which run as high as five
hundred feet per minute. But great as has been the increase in the
production of paper, the demand has kept pace steadily. The wonderful
product of the rag-bag holds an invincible position in the world's
economy.
For machine-finished book and print papers, as well as for other cheaper
grades, the process ends with the calenders, after which the paper is
slit into required widths by disc-knives which are revolving, and so cut
continuously.
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