Pump arrangement

Model of pump arrangement, used at the building of the Stockholm lock (1744-1755). In the inventory of 1779, this model is described: "Model of a different kind of hoisting device for water, consisting of four large pumps driven by a such large treadmill that 30 men were commanded to maintain the steady running. Of these 30 men, 20 continously treaded on each side of the wheel, meanwhile 10 rested, who in order alternated with the workers on either side of the wheel. This pump arrangement transported a great quantity of water, which was necessary depending on the seabed of poppy stones, causing a lot of water leaking in". The model is numbered "N:o 95" and i labeled "Model with four pumps with treadmill, by Councilor of Commerce Polhem.".