The CRC Press, LLC is an American publishing group that specializes in producing technical books. Many of their books relate to engineering and mathematics, their scope includes books on business and information technology. CRC Press is now a division of Francis, itself a subsidiary of Informa; the CRC Press was founded as the Chemical Rubber Company in 1903 by brothers Arthur and Emanuel Friedman in Cleveland, based on an earlier enterprise by Arthur, who had begun selling rubber laboratory aprons in 1900. The company expanded to include sales of laboratory equipment to chemists. In 1913 the CRC offered a short manual called the Rubber Handbook as an incentive for any purchase of a dozen aprons. Since the Rubber Handbook has evolved into the CRC's flagship book, the CRC Handbook of Chemistry and Physics. In 1964, Chemical Rubber decided to focus on its publishing ventures, in 1973 the company changed its name to CRC Press and exited the manufacturing business, spinning off that line as the Lab Apparatus Company.
In 1986 CRC Press was bought by the Times Mirror Company. Times Mirror began exploring the possibility of a sale of CRC Press in 1996, in December announced the sale of CRC to Information Ventures. In 2003, CRC became part of Francis, which in 2004 became part of the UK publisher Informa. Chapman & Hall MathWorld CRC Press website
A thousandth of an inch is a derived unit of length in a system of units using inches. Equal to 1⁄1000 of an inch, it is referred to as a thou, a thousandth, or a mil; the plural of thou is thou, while the plural of mil is mils. Thou is pronounced like; the words are shortened forms of the English and Latin words for "thousand". The US customary mil can be confused with the millimetre, the standard meaning for "mil" or "mils" in British English and European engineering circles; this can cause problems with spoken dimensions or with those who are not familiar with alternative uses of the term. One US mil is 1⁄40 millimetre at 0.0254 mm, or 25.4 micrometres. The thou, or mil, is most used in engineering and manufacturing. For example in specifying: The thickness of items such as paper, foil, paint coatings, latex gloves, plastic sheeting, fibers For example, most plastic ID cards are about 30 thou in thickness. Card stock thickness in the US is measured in points or mils that gives the thickness of the sheet in thousandths of an inch.
Manufacturing dimensions and tolerances, such as: In the manufacture of older automobile engines In the servicing of older automobile engines The manufacture of printed circuit boards Tolerance specifications on hydraulic cylindersThere are compound units such as "mils per year" used to express corrosion rates. A related measurement for area known as the circular mil, is based on a circle having a diameter of one mil. In machining, where the thou is treated as a basic unit, 0.0001 inches can be referred to as "one tenth", meaning "one tenth of a thou" or "one ten thousandth". Machining "to within a few tenths" is considered accurate, at or near the extreme limit of tolerance capability in most contexts. Greater accuracy apply in only a few contexts: in plug gauge and gauge block manufacturing or calibration, they are expressed in millionths of an inch or, alternatively, in micrometres. In the United States, mil was once the more common term, but as use of the metric system has become more common, thou has replaced mil among most technical users to avoid confusion with millimetres.
Today both terms are used. 1 thou is equal to: 0.001 international inches 0.0254 mm, or 25.4 μm For machinists who need to maintain a continual "horse sense" of relative size, it is useful to have a gut feeling for the following. 1 thou is about 0.025 mm. 10 thou is about 0.25 mm. 1 tenth is about 2.5 μm. 1 μm can be thought of as half a tenth. 1 mm is about 40 thou. The introduction of the thousandth of an inch as a sensible base unit in engineering and machining is attributed to Joseph Whitworth who wrote in 1857:...instead of our engineers and machinists thinking in eighths and thirty-seconds of an inch, it is desirable that they should think and speak in tenths and thousandths... Whitworth's main point was to advocate decimalization in place of fractions based on successive halving. Up until this era, workers such as millwrights and machinists measured only in traditional fractions of an inch, divided via successive halving only as far as 64ths; each 64th is about 16 thou. Communication about sizes smaller than a 64th of an inch was subjective and hampered by a degree of ineffability—while phrases such as "scant 64th" or "heavy 64th" were used, their communicative ability was limited by subjectivity.
Dimensions and geometry could be controlled to high accuracy, but this was done by comparative methods: comparison against templates or other gauges, feeling the degree of drag of calipers, or repeatably cutting, relying on the positioning consistency of jigs and machine slides. Such work could only be done in craft fashion: on-site, by feel, rather than at a distance working from drawings and written notes. Although measurement was a part of the daily routine, the highest-precision aspects of the work were achieved by feel or by gauge, not by measuring; this in turn limited the kinds of process designs that could work, because they limited the degree of separation of concerns that could occur. The introduction of thou as a base unit for machining work required the dissemination of vernier calipers and screw micrometers throughout the trade, as the unit is too small to be measured with practical repeatability using rules alone. (Most rule markings were far too wide to mark a single mil, if such dividing is accomplished, it is illegible to the naked eye, being discernible but not useful for me
Helen's Babies is a humorous novel by American journalist and author John Habberton, first published in 1876. The book's full title is: Helen's Babies: With Some Account of Their Ways Innocent, Angelic, Impish and Repulsive, Also, a Partial Record of Their Actions During Ten Days of Their Existence. In its early editions the author was noted anonymously as "By Their Latest Victim". G. K. Chesterton included an essay on Helen's Babies in his collection Generally Speaking; the book is cited in George Orwell's 1945 essay "Good Bad Books" as an example of "the kind of book that has no literary pretensions but which remains readable when more serious productions have perished." It is discussed by Orwell in his 1946 essay "Riding Down from Bangor". The book was adapted for the stage, played at the Broadway Theatre in New York in 1878, elsewhere. Helen's Babies was adapted into a film of the same name in 1924, directed by William A. Seiter. Works by John Habberton at Project Gutenberg Helen's Babies public domain audiobook at LibriVox