Comparison between filtering stones, a £3.3s. a £7.7s. and Collier's machines, a 21s. upwards.
Collier (Manufacturer of Filtering Machines : Southwark, England)
[London] : Geoghegan, printer, Kent-Street,
[1800?]
"Sold at No. 47, Leadenhall Street; and at the Manufactory, No. 18, Kent Street, Southwark".
ESTC
http://galenet.galegroup.com/servlet/ECCO?c=1&locID=nlibscot&stp=Author&ste=11&af=BN&ae=T153282&tiPG=1&dd=0&dc=flc&docNum=CW105928794&vrsn=1.0&srchtp=a&d4=0.33&n=10&SU=0LRL+ OR+0LRI