From How To Do – A Consulting Library For Every Want by L.W Yaggy. (First edition – Circa 1901)
In the early part of the year, if the grass assumes a brighter color in one particular part of a field than in the remainder, or, when the latter is ploughed, if a part be darker than the rest, it may be suspected that water will be found beneath it.
In summer the gnats hover in a column, and remain always at a certain height above the ground, over the spots where springs are concealed.
In all seasons of the year, more dense vapors arise from those portions of the surface from which, owing to the existence of subterranean springs, a greater degree of humidity gives rise to more copious exhalations, espectally in the morning or the evening. It is for this reason that the well—sinkers of northern Italy go in the morning to the places near which is desired to sink a well; they lie down upon the ground and look toward the sun to endeavor to discover the places in the neighborhood from which denser vapors may arise than from the rest of the field.
The springs to which these rules apply are such only as are near the surface; when the source is lower they are rarely sufficient, and the only safe guide is boring; but to execute such operations with any chance of success, a certain knowledge of elementary geology is absolutely necessary. Provided the sources do not descend to any very great depth, that subterranean waters follow precisely similar laws to those upon the surface holds good; but when they are deep—seated; many disturbing causes, to be noticed hereafter, modify their action. If, in a valley formed in a diluvial or alluvial deposit lying upon a more retentive stratum, the two sides are of the same height, the water must be sought in the middle; and if, on the contrary, one side be steeper than the other, the stream would pass nearer the steeper side; in both cases supposing that the materials of the upper stratum are equally permeable throughout, and that the depression of thy lower stratum presents a tolerably regular basin-like depression. Springs are often not to be met with at the head of valleys, but they are much more frequently found to be at the intersection of the secondary valleys with the principal one; and the most favorable point for finding water is usually that which is farthest from the intersection of these valleys, and in the lower parts of the plain succeeding them, at precisely those positions where there is the least water upon the surface.
When the transverse valleys giving forth streams to a river in the bottom of a longitudinal valley are nearly at right angles to the direction of the latter, the quantity of water they yield is less than when they form an acute angle with it. This law holds equally good with subterranean as with surface waters and it may therefore be laid down as a maxim that the most favorable point for seeking a supply by a well would be at the mouth of long transverse valleys inclined to theprincipal one.
If the structure of the earth consists of stone with many veins, such as red shale, water is found almost any where except on the tops or near the tops of hills. Boring, of course, is a perfect test, and where there is great doubt and wells may be dug very deep (judging by others in the neighborhood), this ought to be resorted to. Much can be guessed at in this way. In a neighborhood lying between a tolerably regular series of elevations, the subterranean water will probably be at a regular level. If there are any wells already in existence with a steady supply of water, you have only to ascertain how much higher or lower the surface at the selected spot is than atthe well already, made. If you are ten feet higher, your well must be ten feet deeper than the one made, and vice versa. This difference in level can be ascertained with a leveling instrument, or with a shrewd man by guess.
Everything in this world depends upon will.