CHAPTER XI. NOTES UPON THE FAILURE OF DOCK AND OTHER WALLS FROM A FORWARD MOVEMENT OF THE EARTH FILLING OR BACKING—CONSIDERATION OF THE CAUSES OF SUCH ACTION AND SOME PREVENTIVE AND REMEDIAL MEASURES 198–215 CHAPTER XII. NOTES UPON SLIPS OF EARTH, SUBSIDENCES, AND MOVEMENT IN FOUNDATIONS CAUSED BY “BOILS,” OR AN UPWARD RUSH OF WATER IN LOOSE EARTHS—CONSIDERATION OF SOME PRECAUTIONARY AND REMEDIAL OPERATIONS 216–225 EARTHWORK SLIPS AND SUBSIDENCES UPON PUBLIC WORKS. CHAPTER I. INTRODUCTION—GENERAL CONSIDERATIONS—ENUMERATION OF THE PRIMARY CAUSES OF SLIPS AND SUBSIDENCES IN CUTTINGS AND EMBANKMENTS, AND EARTHWORKS CONSTRUCTED TO CONTAIN OR EXCLUDE WATER—SOME DOMINANT PRINCIPLES TO BE REMEMBERED IN DETERMINING THE LOCATION OF EARTHWORKS. Earthslips and subsidences may be caused by the terrible power of an earthquake or other dreaded subterranean destroying force, upheaving, cracking, and shattering the earth’s crust and dealing death and havoc in its awe-inspiring course. They may also originate from the untiring efforts of the meanest rodents or the most minute crustaceous animals burrowing passages for aqueous action, the chief agent of the instability of the surface soils of the earth. The ceaseless mutability of the created elements has been thus magnificently described:— “For know, whatever was created needs To be sustain’d and fed; of elements The grosser feeds the purer, earth the sea, Earth and the sea feed air, the air those fires Ethereal, and as lowest first the Moon; Whence in her visage round those spots, unpurg’d Vapours not yet into her substance turn’d. Nor doth the Moon no nourishment exhale From her moist continent to higher orbs. The Sun, that light imparts to all, receives From all his alimental recompense In humid exhalations, and at even Sups with the ocean.”