Probably most people have somewhat the ideas of a worthy lady, who asked me how to begin to excavate a ruined town--should she begin to dig at the top or at the side? A cake or a raised pie was apparently in her mind, and the only question was where to best reach the inside of it. Now there are ruins and ruins: they may differ greatly in original nature, in the way they have been destroyed, and in the history of their degradation. The only rule that may be called general, is that digging must be systematic; chance trenches or holes seldom produce anything in themselves, they are but feelers. The main acquirement always needed is plenty of imagination. Imagination is the fire of discovery; the best of servants, though the worst of masters. A habit of reasoning out the most likely cause, and all other possible causes, for the condition of things as seen, is essential. If there is a slope of the ground, a ridge, a hollow--Why is it there? What can have produced it? and Which cause is the most probable for it? The mere form of the ground will often show plainly what is beneath it. Is there a smooth uniform mound of large size? Then a mass of house ruins of a town may be expected. Is there a steep edge to it around? Then there was a wall, either of the town or of some one large building which forms the whole ruin. Is there a ring of mounds with a central depression? Then there was a temple or large permanent building, with house ruins around it. Is there a gentle slope up one side, and a sharp fall on the other? Then it is a rubbish mound. Is the mass high above the general soil? Then several successive layers of habitation may be expected. So, even from afar, some ideas may be gleaned before setting foot on a ruined site. [Illustration: 112. FORMS OF RUBBISH-HEAP, AND OF RUINS OF BUILDING.]