LESSONS IN GEOLOGY. 387 



square. The system is simply the application of latitude and 

 longitude to land measurement, and was first used in Ohio. 



The following sample description will show the practical work- 

 ing of the system : Five acres being the south half of the north- 

 west quarter of the northeast quarter of the southeast quarter 

 of section twelve (12), township ten (10), north of range nine (9), 

 west of the second principal meridian. From the foregoing one 

 can easily interpret the description of an ordinary deed. If you 

 wish to locate a certain tract of land, hill, stream, or ledge of 

 rock, borrow a deed of the land or of some in the immediate 

 neighborhood; make a diagram of a township and locate the 

 land described in the deed on the diagram. Sometimes the one 

 description solves the whole question of location; sometimes one 

 may have to consult several deeds, and may need to ask some one 

 to point out a few section lines and corners before a given locality 

 is fixed satisfactorily. 



After locating a few prominent points, find out by measure- 

 ment where the streams you wish to locate cross the section lines, 

 and if very crooked, where they cross the quarter-section lines 

 also, then map in the stream across the section as accurately as 

 possible. In this work a pocket compass is useful. For measur- 

 ing use the surveyor's chain or tape measure, if possible, but for 

 much of such work many people can learn to step off the distance 

 with sufficient accuracy. A little practice in walking over a meas- 

 ured distance, as 100 feet will enable one to walk with 2-foot 

 step. The field work for some of the finest geological maps I ever 

 saw was done with a pocket compass and step measurement. The 

 elevations were taken with an aneroid barometer. But the eleva- 

 tion of a moderately steep hill can be determined quite closely 

 without instruments. Measure accurately the height of the eye 

 from the ground, then practice in "standing straight" and 

 ''looking level " will soon enable one to stand at the foot of a hill 

 and note on its side a point on the level of his eye, then advanc- 

 ing to that point, note another, and so on until the summit is 

 reached, when the product of the number of stations by the 

 elevation of the eye gives the approximate elevation of the hill. 



