{"product_id":"1930s-fowler-s-long-scale-calculator-in-original-leather-case-vintage-english-circular-slide-rule","title":"1930s Fowler’s Long Scale Calculator in Original Leather Case | Vintage English Circular Slide Rule","description":"\u003cp\u003eFor the man of numbers … a fine Fowler’s Long Scale Calculator, c. 1925-1945, made by Fowler \u0026amp; Co. of Manchester, England and complete with its original leather carrying case. Measuring 2-11\/16 inches across, this double-sided circular slide rule provides a long logarithmic scale for multiplication and division on one dial, while the reverse includes scales for reciprocals, logarithms, square roots, and trigonometric calculations.  In excellent vintage condition and fully functional, it would make a distinctive gift for an engineer, teacher, or collector of vintage scientific instruments.\u003c\/p\u003e\n\u003cp\u003eWilliam Henry Fowler established the Scientific Publishing Company in Manchester in 1898, and his son Harold began manufacturing circular calculators around 1908. The family firm produced these instruments by hand, developing a range of models for engineers, draftsmen, and science students. By rotating the scales beneath the glass, users could perform multiplication, division, and more advanced calculations, gaining approximately 30 inches of calculating scale in a pocket-sized instrument.\u003c\/p\u003e\n\u003cp\u003eIn 1920, the Fowlers moved production to larger premises at Station Works in Sale, near Manchester. Four years later, William Henry and Harold Fowler patented an improved mechanism that allowed the dials on opposite faces to be operated independently using two side-mounted controls. This arrangement became a defining feature of their pocket calculators, including the Long Scale. \u003c\/p\u003e\n\u003cp\u003eCircular slide rules offered several practical advantages over conventional straight rules. Their scales were protected beneath glass, and the continuous circular arrangement avoided the need to reverse a slide when a calculation ran beyond its end. Fowler’s instruments were also unusually costly to manufacture: early models required numerous precision-made parts and hand assembly, and were priced at approximately four times the cost of comparable straight slide rules.\u003c\/p\u003e\n\u003cp\u003eDimensions: (Rule, not including suspension ring) 2-11\/16” D x 7\/16”; (Case, Closed) 3-1\/2” x 3-13\/16” x 5\/8”\u003cbr\u003eWeight: (Combined) 6.4 oz.\u003c\/p\u003e\n\u003cp\u003eCondition notes: Calculator in excellent antique condition overall, with light surface wear to outer metal rim consistent with age and handling. No significant dents or damage noted. Glass on both faces is clean and clear, with no visible scratches or chips. Both dials remain clean, evenly toned, and easy to read, with crisp, legible scale markings. Both knurled control wheels operate as intended, and instrument remains fully functional, although not tested for accuracy.\u003c\/p\u003e\n\u003cp\u003eFront face is marked “FOWLER’S LONG SCALE CALCULATOR PATENT FOWLER \u0026amp; Co MANCHESTER” and includes a six-turn long logarithmic scale and shorter outer scale for multiplication and division. Reverse is marked “FOWLER’S CALCULATOR PATENT FOWLER \u0026amp; Co MANCHESTER” and includes scales for multiplication and division, reciprocals, common logarithms, square roots, logarithmic sines, logarithmic tangents, and small-angle sine calculations. All printed scales and markings remain clear and legible.\u003c\/p\u003e\n\u003cp\u003eOriginal brown leather carrying case shows scratches, rubbing, marks, and areas of discoloration consistent with age and use, retaining an attractive age-worn patina. Leather remains sound, with all stitching intact and flap and retaining-band closure functioning as intended. Front band is embossed “Fowler’s CALCULATOR.” Case has been lightly cleaned and polished.  Other objects in photos not included.\u003c\/p\u003e\n\u003cp\u003eAll items are hand-wrapped and packed with care for secure delivery. We offer flat rate shipping via USPS Ground Advantage for $10, or USPS Priority Mail for $15. Orders over $100 (not including taxes) ship free via USPS Priority Mail — any shipping charges for orders over $100 will be refunded after checkout. We pack with safety and care using recycled and recyclable materials whenever possible.\u003c\/p\u003e\n\u003cp\u003eSorry, no returns or cancellations.  Please view all photos for more detail and feel free to contact the shop with any questions prior to purchase.\u003c\/p\u003e\n\u003cp\u003eFor more unique gift ideas, visit our shop at: https:\/\/pickessandparr.etsy.com\u003cbr\u003eFind us on Instagram at: https:\/\/www.instagram.com\/pickessandparr \u003cbr\u003eFind us on Facebook at: https:\/\/www.facebook.com\/pickessandparr\u003c\/p\u003e\n\u003cp\u003e#mensgifts #sliderules #fowlerssliderules #scientificinstruments #vintagesliderule\u003cbr\u003e\u003c\/p\u003e","brand":"Pickess \u0026 Parr","offers":[{"title":"Default Title","offer_id":44269441843287,"sku":null,"price":259.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0598\/9302\/2807\/files\/PSX_20260907_105358.jpg?v=1789154096","url":"https:\/\/www.pickessandparr.com\/products\/1930s-fowler-s-long-scale-calculator-in-original-leather-case-vintage-english-circular-slide-rule","provider":"Pickess \u0026 Parr | Vintage Objects for Gentlemen","version":"1.0","type":"link"}