Where a cesspit is unavoidable, perhaps the best and least offensive system for emptying it is the pneumatic system.  This is applicable to the water closet refuse alone.  The pneumatic system acts as follows:  A large air-tight cylinder on wheels, or, what answers equally, a series of air-tight barrels connected together by tubes about 3 in. diameter, placed on a cart, brought as near to the cesspit as is convenient; a tube of about the same diameter is led from them to the cesspit; the air is then exhausted in the barrels or cylinder either by means of an air pump or by means of steam injected into it, which, on condensation, forms a vacuum; and the contents of the cesspit are drawn through the tube by the atmospheric pressure into the cylinder or barrels.  A plan which is practically an extension of this system has been introduced by Captain Liernur in Holland.  He removes the faecal matter from water closets and the sedimentary production of kitchen sinks by pneumatic agency.  He places large air-tight tanks in a suitable part of the town, to which he leads pipes from all houses.  He creates a vacuum in the tanks, and thus sucks into one center the faecal matter from all the houses.  Various substitutes have been tried for the cesspit, which retain the principle of the hand removal of excreta.  The first was the combination of the privy with an ashpit above the surface of the ground, the ashes and excreta being mixed together, and both being removed periodically.  The next improvement was the provision of a movable receptacle.  Of this type the simplest arrangement is a box placed under the seat, which is taken out, the contents emptied into the scavenger’s cart, and the box replaced.  The difficulty of cleansing the angles of the boxes led to the adoption of oval or round pails.  The pail is placed under the seat, and removed at stated intervals, or when full, and replaced by a clean pail.  In Marseilles and Nice a somewhat similar system is in use.  They employ cylindrical metal vessels furnished with a lid which closes hermetically, each capable of holding 11 gallons.  The household is furnished with three or four of these vessels, and when one is full the lid is closed hermetically, the vessel thus remaining in a harmless condition in the house till taken away by the authorities and replaced by a clean one.  The contents are converted into manure.  In consequence of the offensiveness of the open pail, the next improvement was to throw in some form of deodorizing material daily.  In the north of England the arrangement generally is that the ashes shall be passed through a shoot, on which they are sifted—­the finer fall into the pail to deodorize it, the coarser pass into a box, whence they can be taken to be again burned—­while a separate shoot is provided for kitchen refuse, which falls into another pail adjacent.