Circular rules The advantage of these rules was that they could provide long scale lengths, and hence increased accuracy, in a small space. Their disadvantage was that it was difficult to fit in a full range of scales.
Maker	Model	Notes		Origin
Circulator	None given	Made by a little known British manufacturer
Fearns	Circular slide rule	Has an interesting spiral log log scale
Concise	28N	Carries "Time Life books" logo	Original instructions.
Concise	4028	Another promotional rule from Concise
Concise	CTCS-552	Carries "Shell" logo.
Concise	300B	A duplex circular rule
Gilson	Midget	A rule with some good ideas and some strange scales	Instruction for drill and thread scales.
Gilson	Binary	A larger version of the above
Aristo	Nr 622	A fairly basic rule.
Graphoplex	Roplex	Scales are turned by knurled knobs.	Original instructions (in French).
Eckell	Dial-O-Matic	Very full selection of scales
ALRO	200R	Box doubles as desk stand for rule
Fearns	Trigonometrical	Sepcially for trigonometrical calculations	Original instructions

Notes:
Original instructions: scanned version of maker's original instructions
Full instructions: complete instructions based on book or similar.
Instructions: instructions based on my own research.
For some rules instructions are given for special scales only.