If 1/8-inch! Is the paper too thick enough to roll along platen?

The letter which Sholes penciled "Is this paper thick enough?" hears a cardboard of an eighth of an inch thick.

Sholes typed a letter to Densmore. Oct. 28 is not be accurate, and might be 18, 1869, on cardboard an eighth of an inch thick, and added a penciled note in which he triumphantly asked, " Is this paper thick enough?

eight inch thick cardboard Sholes Densmore - Google book search

APKY(Associate Professor Koichi Yasuoka) might think in a book(cf. Koichi Yasuoka and Motoko Yasuoka: Myth of QWERTY Keyboard, NTT Publishing, Tokyo (2008)):

• the letter on Oct. 18th 1870 was typed on a similar model of machine of the patent No.118491 by Sholes,
  1. with the paper attached roll-up around on the platen, .
  2. (or the cardboard put as flat and weighed by the roller
     but this is funny cause the roller could run around only in one way..

I guess another alternative possibility:
Sholes might just only change the setting way of ink-ribbon rolled-downward, on old-type-machine, for testing..
and set the ink-ribbon under the surface of cardboard that Sholes typed at.