ACUMATH model #4. This magnifying cursor worked very
well. The scales are finely divided.
This is a 10 inch rule but the width is the same as a pocket rule; only
28 mm.
The advertisement for the new, 1965, model #4.
It
was sold in this plastic pouch. Included was a registration
card with an unlimited
replacement guarantee of quality. Also instructions for adjusting
cursors and brackets, a price list for
replacement cursors, screws, springs and manuals as well as the
self-teaching
manual. In spite of the low model number this slide
rule was developed in 1965. It was developed to sell at $1.25
retail in order to break the price barrier. The narrow size saved
on vinyl stock. The
polyethylene pouch was intended to serve as a sheath. Packaging
was economical and not rounding the corners saved a production
step. Very few were sold because production scale-up was interrupted by
the company being sold to Sterling, making this rule hard
to find.