A  History of the Festus Manufacturing Company
and its successor the Acu-Rule Mfg. Co.
Makers of the Acu-Rule and ACUMATH Slide Rule

Copyright George E.  Keane November 30,  2004 Festus, Missouri.

This is a revised and updated version November, 2006

copyright November 24, 2006



Events in Mt. Olive, Illinois must be considered when reporting Acu-Rule’s future.  The Mount Olive Herald reported on October 5, 1945 that the Slide Rule and Scale Engineering Co., headed by G. L. Lockhart, was making plans to move into the new industrial park. Their previous locations were La Porte and New Carlisle, Indiana.  Mr. Lockhart's company had a leading position since 1930 in improving the ease of reading slide rule scales.  They designed 127 different rules for industrial use.  In 1940 the company took steps to start doing its own production and on July 25, 1946 was incorporated to make slide rules in Mt. Olive.

On February 14, 1947 the biggest fire in Mt. Olive history destroyed part of the factory. Production resumed in remaining buildings.  However, things did not go well for Mr. Lockhart and on  April 14, 1950 the company was declared bankrupt. I have always thought it was more than coincidence that this is the same day Mr. Muschong filled to established the “Acu-Math Co.” name.    An action for dissolution was filed in June, 1950.  On September 13, 1950 the creditor's negotiations began.  Nicholas Muschong and his father were friends of Lockhart and I have wondered if Muschong was a  purchaser of some equipment and patent rights in the liquidation.  


On  March 29, 1954 the Acu-Rule Mfg. Co. requested and was granted certification to operate in the State of Illinois and the registered office was to be in Mt. Olive.  The company officers were President W. J. Boos; Vice President Nicholas Muschong; Secretary Paul Lazare; with the same persons being the company Directors.  Acu-Rule moved into the factory formerly used by G. L. Lockhart's company.  The factory address is listed as Box 142,  Mt. Olive, Illinois.  By 1956 Nick Muschong became the owner of Acu-Rule and brought the brand to a higher level of quality.  Manuals were standardized now with three styles:  No. 13 for Trig/Log Log but the number was never placed on the manual;  No. 44 for Mannheim 10 inch rules;  No. 44P for Mannheim pocket rules in a 4 inch X 6 inch format.


In 1958 there were 25 employees working for the Acu-Rule company.  They made 24 varieties of ACUMATH slide rules ranging in price from $1.00 to $15.00.  The base was still the laminated, eight layers of a special vinyl film that was produced by Bakelite.  Their magnesium core slide rules were made in a similar way by adhering the film to both sides of the magnesium core to produce a stable body.

According to the last plant manager, the Mt. Olive plant did produce slide rules for other companies. Three models of slide rules were made for the Dietzgen Company and marked as Dietzgen 1757, 1767 and 1772. One was a copy of the model 400 and black plastic brackets were applied. Acurule could make the rules at a lower cost than Dietzgen could.  The lower cost labor available in a small town gave Acurule an advantage and considering that the Lockhart opration left a trained labor pool the move to Mt. Olive from St. Louis was a good business decision.  The Fullerton Acu-400 and Acu-1311 were produced by the Acu-Rule Mfg. Co.    A Concrete Volume Calculator slide rule was also produced in very large numbers.  A special slide rule was made for C. V. Ore in Harvey, Illinois.  Some special slide rules were made for private companies. By 1966 the officers and the Board of Directors are all named Muschong.  Nicholas is President and Treasurer, Peter  is vice-president and Maria is Secretary.  

After seeing the Texas Instruments electronic hand held calculators, Nicholas  Muschong understood the impact that  hand held electronic calculators would have on the slide rule as soon as their  price came down.  Sterling Plastics in Mountainside N.J. was trying to expand their slide rule line and in 1966 had been talking to Acurule about buying the company. This time Muschong promptly sold the company to George and Mary Staab of Mountainside N.J. on June 25, 1968.  Development work had been planned  for a circular slide rule and a 20 inch slide rule but the work never started because of the sale. Production scale up of the recently developed model #4 was cancelled. Sterling Plastics operated the Mt. Olive plant for about a year with the Acu-Rule production staff  producing slide rules under the Acumath brand but did not use their SP logo. After moving to N.J. the Acumath slide rules were marked with the Sterling Plastics trademark  symbol.  Note that Sterling had been making slide rules prior to buying Acu-Rule and an example is the Sterling 594 with a copyright date of 1965 and using the SP logo.

After a short time, a filing was made by the Staabs on April 18, 1969 to dissolve the Acu-Rule Mfg. Co. and it was  officially liquidated on September 24, 1969 as a Missouri Corporation by the Missouri Secretary of State.  Six months later a filing was made in New Jersey to withdraw the Acu-Rule Mfg. Co. and this was approved in March, 1970. 

At some point Sterling Plastics was bought and operated as a division of the Borden Chemical Company, however the Sterling Plastics name was retained.  Large numbers of low cost plastic slide rules were produced by Sterling Plastics.


The life span of the Festus Mfg. Co. was about two years having started in Festus, Missouri in 1938 and into 1940.  Mr. Jones took the company to Saint Louis as the Acu-Rule Mfg. Co. and operated it for five more years until his death.  There were then a number of management changes and relocations until it was dissolved in 1969. 

The Festus Mfg. Co. and the Acu-Rule Mfg. Co. filled an important need during the Depression years of 1938 to 1940 and during WWII as a supplier of a low cost, student grade, wood slide rule as well as providing  production capacity for
other brand names.  If Paul Jones had  lived to see the development of the metal core rules, the low cost vinyl rules and the manufacturing of the high end 1311 types he would have been very pleased with the company he started with just a few scraps of wood and paper.

 The company name of Acu-Rule Mfg. Co. was used from 1940 to 1969.  The company Mr. Jones started lasted 31 years before being sold to Sterling Plastics.