DICAS (John). Directions for Using the Patent Saccharometer, for brewing ale and beer, at all times to the same strength, also shewing the comparative value of malt, &c. Invented by the late John Dicas, and for upwards of sixteen years, made only by his daughter and successor, Mary Arstall, late Mary Dicas, mathematical instrument maker, Liverpool: the only proprietor of the patent, who, for some time previous to the decease of her father, assisted in making the above instruments. The manufactory of the patent saccharometers, hydrometers, and lacto-meters, was for some time carried on by M. Arstall, under the firm of Dicas & Co.1814

Liverpool: Printed by M. Galway & Co. First (only?) edition, 12, [1, list of instruments with prices], [1, blank]pp., recent paper wrappers. John Dicas was a scientific instrument maker, active in Liverpool, between 1774 and 1797. He was succeeded by his daughters Mary and Ann, who continued to operate the business until some time after 1837 when it was then taken over by Joseph Long. In 1780 John Dicas was awarded UK patent 1,259 for "constructing hydrometers with sliding-rules to ascertain spirit strength". (Hopp, 'Slide Rules. Their History, Models, and Makers'. 1999). A printed thirteen-line "Caution" on verso of the title-page warns against instruments on sale in London and Dublin stamped "Dicas" which are not of of her [Mary Arstall] manufacture. Not traced in Copac or OCLC.