26 Survey of Oyster Bars, Somerset County, Md. 



They then gradually proceed from general descriptions of the surroundings of a land- 

 mark to the specific details of the character of the center and reference markings. An 

 examination of the descriptions themselves will best indicate the method followed. 



The heading of each description is the name by which the landmark or triangulation 

 station is known and designated in all work and records of the Government and State. 



Under the heading of "Locality" the first paragraph gives a description of the 

 general locality of the landmark and the serial number of the published "Chart of 

 Oyster Bars" of Maryland which best shows its location. The published charts are on 

 the large scale of i part in 20,000, and show the location of the triangulation stations 

 so clearly that in many cases the written descriptions will not be required to find them. 



Under the same heading of "Locality" the second paragraph furnishes the descrip- 

 tion of the immediate locality of the landmark and refers to the bearing and distance 

 of standard cement monument marking the reference station, as it is the first object 

 that is likely to catch the eye when the immediate vicinity of the desired station is 

 reached. 



Under the heading of "Marks" a description is given of the character of the mark- 

 ings of the "observed station" and the reference station. It will be noted that, although 

 the "observed station" is the one "occupied" and "observed on" for horizontal angles, 

 and also the one whose geographic position is computed, frequently it is not marked 

 as well as the reference station, and in many instances has only a pine stub to indicate 

 its position. This is the case for the reason that the necessity of intervisibility of land- 

 marks usually made it compulsory to locate these stations on edges of banks and ends 

 of points of land, which in Chesapeake Bay and tributaries generally means that they 

 will be washed away in a short period of years. The past experience of the Coast and 

 Geodetic Survey in this region has shown the necessity of reference marks, if the frequent 

 reestablishment of a new framework of triangulation is to be avoided. 



All the marks designated in the descriptions as "the center point of triangle on 

 standard cement monument " are exactly alike. These monuments are made of cement, 

 sand, and gravel, and are 2 feet long and 8 inches square at top and bottom. Their 

 tops are all marked with the same brass mold and show a center hole surrounded by a 

 triangle, with the letters "M. S. F. C." arranged around the vertex and the letters 

 "U. S. C. S." underneath the base of the triangle. The center hole is always in the 

 center of the top of the monument by construction, and if this is found to have been 

 broken off without disturbing the bottom, the center of its square section can be used 

 as the location of the station. 



All the "standard cement monuments," whether used for marking the "observed 

 station" or "reference station," have been planted upright in exactly the same manner, 

 with their tops projecting 3 or 4 inches above the surface of the ground. 



Therefore, as the above facts in reference to the "standard cement monuments" 

 are a constant element in all cases, the repetition of these facts in the description of 

 stations is made needless by this one statement. 



It is the expectation that the reference stations," the character of which is explained 

 above, will be used in many cases in the near future in the place of the "observed sta- 



To obtain the geographic positions of any of the "observed stations" or of the "reference sta- 

 tions," application should be made to the Superintendent of the Coast and Geodetic Survey at Wash- 

 ington, D. C. 



