How to operate a microtome?
The imnstrument is shown here upside down. If it is turned around, it looks like this:



The glass disc are placed around the middle tube. The operation principle can be seen in this image:



The specimen is placed in the tube in the middle and pushed out by turning the knob at the bottom. The minimal increment for this kind of microtome is 10 micrometers. The razor knife is used to cut the slices of the specimen.
An operation manual can be found here.