Marks & Clerk
British patent agency Marks & Clerk had offices in London, Birmingham, Manchester, and New York. The firm also acted as consulting engineers and published books.
See the title page of E.C.R. Marks's book, The Evolution of Modern Small Arms and Ammunition (link), which lists Marks & Clerk as "Consulting Engineers and Chartered Patent Agents", as well as publishers of the book!
E.C.R. Marks is the biggest apparent player in aeronautics, and there is a series of patents (c. 1911–1914) which bear his name as applicant. In these cases he seems to function as a more active proxy of petitioners "from abroad" such as Siemens-Schuckert-Werke G.m.b.H. as well as individuals.
Marks & Clerk apparently also published a work called Elements of Patent Law "(For Private Circulation only)", as well as several books on mechanical topics, many by E.C.R. Marks himself.
It is perhaps no surprise that in Patent GB-1913-22125 for a a certain type of ballonet, Marks refers to Patent GB-1897-10811, which he had secured sixteen years earlier, as an archetypal ballonet patent.
In 1897 the firm had these addresses:
- 18, Southampton Buildings, London, W.C.
- 13, Temple Street, Birmingham
In 1910 they had these addresses:
- 57 & 58 Lincoln's Inn Fields, London, W.C.
- 13 Temple Street, Birmingham
- 25 Market Street, Manchester
1912 and 1913 patents also list this address: 220 Broadway, NYC
Marks & Clerk is still active and international, with a big department for aerospace patents, in 2018. Their company history page doesn't mention E.C.R. Marks or the Broadway office.