Fowler & Co was an important Manchester firm of calculator manufacturers, established in 1908 by William Henry Fowler and his son Harold. William Henry Fowler studied engineering at Owens College, Manchester, and in 1891 became the editor of The Practical Engineer, a weekly journal published in Manchester. In 1898, he set up the Scientific Publishing Company on Corporation Street, Manchester, which began publishing annual pocket books for a variety of trades. The first in the series was Fowler's Mechanical Engineer's Pocket Book. The Scientific Publishing Company also began selling circular calculators produced by other manufacturers in 1898. Harold Fowler joined the company in 1905 and began designing circular calculators. Around 1908, he started manufacturing calculators from his designs in a workshop set up at his home in Sale. This marked the start of Fowler & Co as a manufacturer of calculators. The double-sided Long Scale or Pocket calculator was to be the mainstay of production for the next 30 years. However, the business was not very profitable. Circular calculators had a large number of different parts, compared with straight slide rules, and had to be assembled by hand. Production costs were therefore high and the calculator cost four times as much as straight slide rules. In 1920, the Fowlers moved the business to larger, separate premises at the Station Works, Chapel Road, Sale. Over the next decade, the company introduced the Universal calculator and the Magnum Long Scale calculator which had a maximum scale length of 50in (127cm). By 1929, Fowler & Co employed four machine operators and a works manager. The business was still not very successful, however, and took in various engineering jobs to support the calculator making side. William Henry Fowler died in April 1932 and Harold became owner of the firm. By 1936, the company had introduced another model, the 12-10 calculator, designed for architects, builders, surveyors and timber merchants who often had calculations to make with decimal and duodecimal (12ths) notation. All the company's products were still marketed through the pages of the Fowler’s Pocket Books. The business moved again in 1938 to Hampson Street, Sale, when the Chapel Street works was demolished to make way for the Town Hall extension. It continued to be a general engineering workshop as well as making circular calculators. During the Second World War, Jim Cookson joined the business as the new manager and the company's name was changed soon after to Fowlers (Calculators) Ltd. In 1948, the company introduced the Jubilee Magnum extra long scale calculator which enabled calculations to five or six figures and had a total scale length of 76in (193cm). Later, it produced several new models including the Type B or Textile calculator. The company marketed its full range through Joseph Casartelli & Sons Ltd, scientific instrument makers of Salford, as well as through the Fowler's Pocket Books. Jim Cookson ran the business after Harold Fowler's retirement. In the early 1960s, the company took over as proprietors of the Scientific Publishing Company. Fowlers (Calculators) Ltd carried on trading until it went into liquidation in around 1988 following Jim Cookson's retirement.

Leadbeater & Scott Ltd was incorporated in 1908, following the dissolving of an existing partnership between Edwin Leadbeater, Francis Liddle Scott and James Wing. The new company was a partnership between Edwin Leadbeater and Francis Liddle Scott. Leadbeater & Scott Ltd continued producing cast and bar steel from St Mary's Works, Sheffield, the site that the previous company occupied from 1846. The company continued trading until the 1960s.