{{Use dmy dates|date=April 2022}} thumb|Fowler "Magnum" calculator and handbook '''Fowler Calculators Ltd''' was a manufacturer of slide rules and other scientific and mathematical instruments, based in Manchester, England and founded by William Henry Fowler (ca. 1854–1932).<ref name=hopp>{{cite book|title=Slide Rules: Their History, Models, and Makers|first=Peter|last=Hopp|page=108|publisher=Astragal Press|year=1999|isbn=978-1-879-33586-8}}</ref><ref>{{cite journal|url=https://books.google.com/books?id=gidVAAAAYAAJ&q=%22fowler+calculators%22|title=Bulletin of the John Rylands University Library of Manchester|volume=62|publisher=John Rylands University Library of Manchester|page=535|year=1979}}</ref><ref name=":1">{{Cite journal|last=Wetton|first=Jenny|date=June 1997|title=III: Flatters and Garner Limited, and Fowler & Company|url=https://static1.squarespace.com/static/54ec9b40e4b02904f4e09b74/t/567fdf6657eb8dca48f9c78b/1451220838611/SIS_Bulletin_053.pdf|journal=Scientific Instrument Society|volume=53|pages=15–18}}</ref>
==Life of William Henry Fowler== William Henry Fowler, born in Oldham, England, began his interest in engineering and manufacturing around age 14 when he began training in textiles and machinery at the Oldham firm of Platt Brothers.<ref name=":1" /> He then went on to study mathematics at Owens College in Manchester in the 1870s. Following his time at Owens College, he became an assistant engineer for the Manchester Steam Users' Association (ca. 1877–1888) and worked as the general manager at the Chadderton Iron Works Co.<ref name=":1" />
Fowler became editor for the weekly journal ''The Practical Engineer'' in 1891, which led to him starting the Scientific Publishing Company in 1898. That year, ''The Mechanical Engineer''—his weekly journal under the Scientific Publishing Company—published a design for a circular calculator operated by moving fixed pointers over a revolving dial.<ref name=":2">{{Cite journal|date=February 19, 1898|editor-last=Fowler|editor-first=William|title=The Slide Rule|url=https://dds.crl.edu/item/261463|journal=The Mechanical Engineer|publisher=The Scientific Publishing Company|volume=1|pages=113–115|via=Center for Research Libraries}}</ref> It is unknown whose design it was that was originally published in the journal.<ref name=":1" /> Fowler's son, Harold (1879-unknown), also graduated from Owen's College and worked as an electrical engineer before becoming an editor for ''The Mechanical Engineer'' alongside his father in 1905.<ref name=":1" /> Three years later—in 1908—Harold began commercial production of circular calculators in a spare room of the Fowler house in Sale which was converted into a shop. It is uncertain whether W. H. Fowler financed this original setup.<ref name=":1" /> Production included the same design with the calculator's appearance and control resembling that of a pocket watch.<ref name="hopp" />
W. H. Fowler became owner of Fowler & Co. and filed for several patents between the years of 1910 and 1924.<ref name=":1" /> Among these patents were the designs for the company's cornerstone "Pocket" calculators, which the company would continue to manufacture throughout its existence. W. H. Fowler died on April 4, 1932, and Harold took ownership of the company.<ref name=":1" /> Harold continued expanding production, aiming to be used in surveying work, construction, and textile manufacturing.<ref name=":1" /><ref>{{Cite web|title=Pocket Watch Style Logarithmic Circular Slide Rule Calculators|url=https://www.sliderulemuseum.com/PocketWatch.htm|website=International Slide Rule Museum}}</ref> In 1942, Jim Cookson became the new head manager and the company's name was changed to Fowler's (Calculators) Ltd.<ref name=":1" />
Cookson became owner after Harold retired and would carry on production of Fowler's calculators until the company was liquidized following his own retirement in 1988.<ref name=":1" />
== Types of Fowler Calculator == thumb|Harold Fowler's long scale calculator with case. One of the first Fowler calculators with two knobs.
=== Long Scale and "Magnum" Calculators === Following the patent and release of Harold's Long Scale calculator featuring two knobs on the outside rim in 1914, he designed the Magnum Long Scale calculator in 1927.<ref name=":0">Fowler, H. (1927). The Fowler "Magnum" Long Scale Calculator: Instructions With numerous Examples. Sale, Manchester: Fowler's (Calculators) Ltd. Retrieved from https://sliderulemuseum.com/Manuals/ISRM_M420_Fowler_Magnum_LongScaleCalculator_Instructions_GiftOfPhilipRodleyNZ.pdf</ref><ref>{{Cite web|title=Fowler's Long Scale Calculator Circular Slide Rule|url=https://americanhistory.si.edu/collections/search/object/nmah_1215043|access-date=March 14, 2021|website=National Museum of American History|publisher=Smithsonian Institution}}</ref> As the name "Magnum" implies, it was a fairly large device at 4.5 inches in diameter—about 1.5 inches more than Fowler's average non-Magnum-series calculators.<ref>{{Cite web|title=Fowler Calculators: The Scientific Publishing Company|url=http://www.mathsinstruments.me.uk/page17.html|access-date=March 14, 2021|website=Mathematical Instruments: A Private Collection}}</ref> The large design meant that much larger calculations could be performed on it, "to four, and sometimes five, significant figures," according to the instruction manual.<ref name=":0" /> Another added benefit of the Magnum's size was its readability. The instruction manual claimed the calculator's size "permits of the use of larger figures and easier reading...Another important feature is that the scales are longer and admit finer graduation."<ref name=":0" />
==References== {{reflist}}
== External links == * [http://www.mathsinstruments.me.uk/page17.html Collection of Fowler Calculators] *[https://www.gracesguide.co.uk/William_Henry_Fowler W. H. Fowler's Obituary at Grace's Guide] *[https://www.sliderulemuseum.com/SR_Dates.htm#Fowler International Slide Rule Museum]
Category:Defunct manufacturing companies of the United Kingdom Category:Manufacturing companies based in Manchester Category:Defunct companies based in Manchester