The manuals next said:

Acu-Rule Mfg. Co. (successor to Festus Mfg. Co.)                      
New York address 15 East 26th St.
Factory & General Offices, Festus, Mo.

This pattern is supported by tax records.  A search of the Festus, Missouri city tax records did not find a record for the Festus Manufacturing Company but a search of the Jefferson County, Missouri Assessment records for 1939 did find a record in the Merchant's Assessment Book on page 198. It is believed the taxes were paid by the Waggener lumber yard while it was under their control and the county tax record is the result of Paul Jones registering the new company that remained for a short time in Jefferson County at the Festus location. Leaving Waggener's ownership seems to have been a friendly separation. 

At the New York address of 15 East 26th St., NY is a very large office building called the Madison Square Building. Mr. Jones hired a person with the interesting name of Magnus M. Manheim as Sales Manager. Using an Acu-Rule Mfg. Co. letterhead,  Mr. Manheim  circulated a sales letter and price sheet with four models of slide rules.  This letter, dated August 14, 1939, 
was directed to wholesale vendors.  This was done prior to the Acu-Rule Mfg. Co. being incorporated in Missouri  and while still located in Festus.   It took very little time for Acu-Rule to be noticed by K & E.  By 12/20/1938 samples and price information was already in the competitors cabinet.

At the same time a catalog from Laboratory Specialties, Inc., a science equipment supply house located at 144 South Wabash St., Wabash, Indiana was offering these slide rules at retail at about 100% markup with quantity discounts.  The same model numbers were used.  It seems the Acu-Rule Mfg. Co. was now in business.

The St. Louis Period

After the 1940 incorporation the company left Festus and was operating in rented quarters at 623 Del Monte Way, St. Louis.  Mr. Paul  Jones  was the President and the Secretary & Treasurer was Mr. Schnure.  From this time on  there was no longer any association with Festus.

In addition to the Acu-Rule product line, custom production of slide rules was done.  One was the Dietzgen Company and the standard Paul Jones type manual that was used made identification easy. A different box was specified by Dietzgen for this wood slide rule. The D. Van Nostrand book company bought slide rules and used a specially designed box.  The rules were a point of sales item placed by their slide rule instruction books. Another company was the Frederick Post Company of Chicago.  These were wood rules with printing directly on the unpainted body. Positive identification was possible because the familiar Paul Jones manual was used with an overprint for the Post Company that included Post’s 1944 oval logo.

In 1944, the company was still operating under the Acu-Rule name with Mr. Jones as president, Russell S. Queen as vice president and General manager.  Katherine Drew Jones, Paul’s wife, was secretary & Treasurer.

In 1945 the company produced a Trig slide rule.  Although Mr. Jones wrote the original Mannhiem type manual he decided to hire Professor Ross Middlemiss to write a new Trig - Mannheim manual.  This was the first major departure from the original style Acu-Rule manual.  The copyright was Paul Jones,  June, 1945.   Mr. Jones died that same month at the age of 49. The company continued and in 1946 Wilfred J. R. Boos became President and Treasure of the company. Mrs. Jones stayed as Vice President and Secretary until 1947 and there was no further association with the Jones family.

Mr. Boos was ready to try new innovations and the company experienced a productive period. By 1946 the metal core slide rules were being sold under the brand name of Acu-Math  and referred to as the "Never Stick Metal Core" slide rule.  In St. Louis considerable effort was expended to developing a wood and plastic laminated rule.  Invariably the wood shrunk more than the plastic and the plastic was left extending beyond the wood.  This problem was never solved and wood and plastic laminates were finally abandon.
A big risk was taken by the company when it used a Vinyl material made by Bakelite. This was not an extruded plastic but a laminate made from eight plies of a special Vinyl film. No one knew if the laminate might separate. We now know it worked very well. Development of Vinyl slide rules may have started as early as 1948. In 1949 Wilfred J. Boos applied for a patent that was granted on April 29, 1952. Patent No. 2,594,857 was for a cursor design and method of assembly.  Eventually the Vinyl film replaced the nitrocellulose lacquer on the magnesium core rules.  In April of 1950 the Acu-rule Mfg. Co. filed to establish a company name of AcuMath Co., but this name was never used. The company moved to Mt. Olive, Illinois in 1954.   Redesigned manuals, No. 44 and No. 13 gave the company location as both St. Louis and Mt. Olive, Illinois. A new, oval shaped logo was designed by Nick Muschong.  Vinyl became the primary material for slide rules produced in the late St. Louis period and in Mt. Olive.