With regard to the deposition of an embankment, one of the chief objects to be accomplished is to make it homogeneous and prevent the formation of solid layers, which may become detached along the line of stratification from less compact strata. Careless and intermittent tipping conducted in dry and wet weather and with different kinds of earth, probably in various conditions, will cause slips and subsidences; as also any local disturbance of the soil, which is always more porous and absorbent of water than when in its natural unexcavated state, although it may be free from water-pressure which may exist in a cutting: and particularly so when fresh-tipped, as then the pressure and strain upon it is at the maximum, its tendency to unstableness gradually decreasing as it becomes consolidated. In hard granular soils this is almost certainly the case, but consequent upon percolation of water into a mass deposited in a dry state that expands; it may not be so in aluminous or other earth having particles affected by moisture, for an additional or an unequal load after a settlement may cause further movement and irregular density. In countries where the ground becomes caked or parched during the dry season, the change to a wet or saturated condition affects them much more than in variable climates, as they are then generally in a moist state. It is easy to decree that no embankment shall be made of any earth of a treacherous character, if the circumstances are known to conduce to instability, and to rigidly specify what shall be done and what shall not be done, but the exigencies of an undertaking may cause such stipulations to be impracticable. For instance, it may be found that no other earth may be available except that which is proscribed. No one with a knowledge of earthwork would desire to erect an embankment of considerable height of yellow or sandy clay, or excavate a deep cutting in such soil unless a considerable allowance be made to provide against contingencies; nevertheless, it has to be done, and will have to be done. The precisianism and delicate refinement of a specification replete with good intentions has, therefore, very frequently to be toned down in order to allow of the execution of work.