are listed in order from top to bottom.
names are the labels actually on the slide rule or in Hemmi documentation.
If the scale name was not easily determinable, then the scale name is
the name in modern use-- "A," "B", "C" etc.
“front” of duplex slide rules is arbitrarily defined to be the
side with the longer stator down. This is usually, but not always,
the side carrying the brand name and model number and the head of the body
changed from time to time. In particular, on some rules all, some,
of the principal
subdivision between 1 and 2 on the C and D scales were explicitly numbered
times. It is
beyond our ability to note such variations.