STATIONARY ENGINES.

233

placed in front of the openings to the pump well. Such substancesare lifted from the face of the grating by an endless chain withbuckets or scrapers and combs attached, working vertically in frontof and close to the grating, the teeth of the combs passing betweenthe bars. On the descent of the chain the buckets are overturnedand discharge their contents into a trough, from which they areremoved by manual labour.

The sewage, after being delivered from the pumps into thewrought-iron trough, is discharged through brick culverts into thereservoir, or, in case of need, provision is made for its dischargethrough other culverts directly into the river. After remaining inthe reservoir until the time of high water, it is discharged by a lower

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_

Fig. 148.—Boilers for Pumping Engines at Crossness. End Elevation.

set of culverts into the river. There are two tiers of eight openingsin each compartment of the reservoir, the upper eight for the admis-