LAND SURVEYS 99 



in danger of being destroyed should be replaced by permanent 

 monuments while the old ones are still visible. A monu- 

 ment should be permanent and easily found. It should be 

 so constructed that it will not be destroyed by road machin- 

 ery. The following materials and methods have been used 

 for replacing monuments: (1) Wooden posts set deep in the 

 ground may be used. Rotten wood and the point can be 

 found for many years if the soil has not been disturbed. 

 (2) A large bowlder with a cross cut on its top can be used, 

 but it is subject to removal by road machinery or may be 

 destroyed by blasting. (3) A cut stone post is easily identi- 

 fied, but may be torn out by a road-grader. (4) Four- or 

 six-inch sewer pipe 30 inches long, filled with concrete, makes 

 a permanent corner easily identified, but it may be torn out 

 with road machinery. (5) A special cast-iron post is easily 

 identified, but may be pulled out in road work. (6) A 

 brick pier 8 inches square and set deep in the ground is 

 easily identified and hard to destroy, since the top may 

 be broken or taken off without disturbance of the lower 

 part. (7) Burnt charcoal, brick, lime, or glass placed under 

 the corner makes it possible to identify the corner location 

 in case the monument itself is destroyed. (8) In excava- 

 tion work the location of the corner may be preserved by 

 means of boring with a two-inch auger to a depth below the 

 point of excavation and filling the hole with material such 

 as lime, cement, plaster of Paris, or sand which can be 

 easily identified after the excavation work is completed 

 and a permanent corner can be set. (9) Old gas pipe, 

 from $i to \% inches in diameter cut 30 inches long, makes 

 a good corner. It can be driven with a sledge in soft ground 

 and placed with an auger in hard ground. After the pipe 

 has rusted out, large scales will be left by which the point 

 can be located. (10) Old boiler flues or pipe 2 or 3 inches 

 in diameter, set in the ground 3 feet deep and filled with 

 concrete, make an excellent corner. When the metal rusts 

 away, the concrete core remains in place. 



