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More than 6 000 000 of porn videos sorted by categories. Wife was raped while on vacation, however she then became the mistress of the rapist and performed every sex act imaginable with him.Dating a slide rule becomes difficult if a manufacturer did not imprinting a date code or serial number on the stock. This comprehensive research will enable you to find the period of manufacture for most every Dietzgen slide rule from 1887 through 1972.The patent may only refer to a certain combination of scales used over a thirty year time on different models. 1911 James Dieterich, who has worked his way up to blueprint foreman at B. Makepeace Co., goes west and lands a job as a salesman with the K&E branch in San Francisco. In general the production rate was about 70,000 rules per year until the 1950s. The 1960s had a production rate of about 100,000 per year for several years and tapering off in the 1970s ending at about 700000.Having contact with the original owner of a slide rule that remembers the year it was purchased helps on determining the age. In general it is safe to assume a linear production rate between the rollover dates particularly for the common types rules.
1950 - Two character date codes appear (see Hemmi date codes).
1983 - The use of Zip 4 Postal Zip Codes began used by USPS Many of the founders of United States firms producing slide rules had their roots as employees in other firms, just as modern entrepenuers break off from their employers and create their own start-up companies. Gustavson, in her article Necessity is the Mother of All Invention (Modern Reprographics, June 2000) is a good example. "N" was used as a prefix many times to denote some change in a given model.