Joseph Casartelli & Son Ltd was established in 1896 when Joseph Casartelli brought his son Joseph Henry into partnership in his existing business. Casartelli was born Giuseppe Luigi Casartelli in 1823 in Tavarnerio, Northern Italy. When he was eleven his family emigrated to Liverpool where they joined other members of the family, who were already producing barometers and thermometers. He Anglicised his first names to Joseph Louis. In 1851, Casartelli moved to Manchester and purchased the instrument making business of Joshua Ronchetti. Casartelli ran the business under his own name, expanding his operation to make additional optical, surveying and engineering instruments. He improved on the design of various instruments and eventually made applications for a total of seven patents for improvements to steam engines, boilers and surveying equipment. In 1877, Casartelli acquired a small workshop in Robert Street, Cheetham Hill but, as business increased, more space to manufacture the instruments and other equipment was required and the company moved to larger premises in Clarence Street. Casartelli's son, Joseph Henry, born in 1862, joined his father’s business and eventually Joseph brought Joseph Henry into partnership with him in 1896, after which the business became known as J Casartelli & Son. Casartelli died in 1900 and the business was carried on by Joseph Henry. In 1905, the works were moved to Hayes Yard, Garrett Street, Manchester. The company continued to expand as a result of the demand for its instruments both nationally and internationally. In 1922 all departments of the company were moved to new premises at 18 Brown Street, off Market Street. In 1929, the company took over the running of the Casartelli business in Liverpool. However, due to the Depression, the Liverpool business went into liquidation in 1933. The Manchester company continued to make and sell surveying and textile testing equipment under the Casartelli name until 1966, when it moved once more to premises on Liverpool Street, Salford.

The observatory was completed in 1769, in time for King George III's observation of the transit of Venus that occurred on 3 June in that year. By 1842, the building had become disused, and was taken on by the British Association for the Advancement of Science and became widely known as the Kew Observatory. Responsibility for the facility was transferred to the Royal Society in 1871. The National Physical Laboratory was established there in 1900 and from 1910 it housed the Meteorological Office. The Met Office closed the observatory in 1980.