Specification of William Frost Sweetland and John Merfield
Subtitle: purifying sewage
Contributors: Merfield, John
Publisher: Great Seal Patent Office
Published: 1871
Place of publication: London
Language: eng
Subjects: Sewage; Sewage disposal plants; Filters and filtration
Notes: Cover title.

At head of title: A.D. 1870, 27th October. No. 2832.

"William Frost Sweetland and John Merfield, of no.216, Goswell Road, Islington, both in the county of Middlesex".