After carefully observing the results of other attempts, some successful and others not, James Simpson in 1829 installed filters at Chelsea, which are almost identical with the present day slow sand filth ers which have done such good work in the past. There were many failures for a long time, notably at Glasgow. Glasgow being then supplied by two rival companies, the Cranston Hill Ca. and the Glasgow Water Ca. The former supplied water from large impounding reservoirs on Cranston Hill which then passed through a filter. The filter was found to be a failure. After three more failures, and spending huge sums of money, the company amalgamated with its rival] in 1858. It would appear that at this time the filters were really looked on as strainers.
Where the source of supply is a tiver, and the strata is favourable, such as sand or fine gravel, the river water has been made to pass through the natural strata into a collecting culvert before entering the supply. Among other places supplied in this way are Genoa, from the river Serivia, and Toulouse, from the fiver Garonne.
Simpson's filter gradually developed into the modern slow sand
Text read from the printed page and cleaned; old type leaves the occasional error.