In 1887 a committee reported that the coupler question was the " knottiest mechanical problem that had ever been presented to the railroad," and over 4000 attempted solutions were on record in the United States Patent Office.
Other offices are the New Record Office, the repository of State papers and other records, and the Patent Office in Chancery Lane.
Besides the Government reference libraries at the British Museum and South Kensington there are other such libraries, of a specialized character, as at the Patent Office and the Record Office.
Patents, designs and trade marks are now dealt with by the patent office under the charge of a controller-general (salary £1800), which is subordinate to the railway department, and copyright, art unions and industrial exhibitions are also among the matters dealt with by the department.
It also contains a complete set of the patent office publications.
