A S S I G N M E N T  11 Textbook  Assignment: “Direct  Leveling  and  Basic  Engineering  Surveys.” Pages  14-1  through 14-25. 11-1. Bench  marks  (BMs)  share  what common   characteristic? 1. They  are  permanent 2. They are marked with a known elevation 3. They are constructed only from concrete  or  brass 4. They are used only for vertical  control 11-2. To  be  used  as  elevation  references in  the  development  or  expansion  of a permanent naval station, you should establish monumented BMs in which  of  the  following  locations? 1. On  all  important  structures, such as buildings and piers 2. At  all  road  intersections 3. In a grid system 1 mile apart 4. In a grid system 1/2 mile apart 11-3. Level nets are established within a prescribed order of accuracy and are  tied  to  what  reference? 1. A BM 2. A traverse station 3. A datum 4. A horizontal control point 11-4. Mean sea level (MSL) differs from mean tide level (MTL) in what way? 1. MSL is the mean of tides observed in the open sea; MTL is the mean of inland tidewater   observations 2. MSL is the result of averaging tabulated  tide  readings;  MTL is taken from the tidal curve 3. MSL is the mean of a large number of points along a tidal curve;   MTL is the mean of only the high and low points along the  tidal  curve 4. MSL is the datum used primarily in hydrographic surveys; MTL is used as a datum in any type of survey 11-5. 11-6. 11-7. 11-8. 11-9. 11-10. The correct way to obtain the MSL value for a month’s tide tabulated record is to add all daily sums for the month and to divide this total by the sum of what specific units of time in that month? 1. Minutes 2. Days 3. Hours 4. Weeks What datum is generally used for measuring the height of a hill? 1. Mean sea level (MSL) 2. Mean high water (MHW) 3. Mean low water (MLW) 4. Mean low water springs (MLWS) Assume you are engaged in a hydrographic survey of the water approaches  to  Naval  Air  Station, Adak, Alaska. Your  soundings should refer to what datum? 1. MLLW 2. MWL 3. MTL 4. MLWS What  type  of  lubricant  is recommended  for  use  on  engineer’s levels  in  arctic  regions? 1. Watch oil 2. Powdered  graphite 3. Petroleum jelly 4. Mineral  oil The proper way to remove an engineer’s level from its carrying case is to grasp it firmly by what part(s)? 1. The  telescope 2. The  footplate 3. The leveling head 4. The wye rings When a level setup must be transferred to another point or station,    what  screws  should  be loosened  slightly? 1. Leg and level 2. Leg and clamp 3. Level  and  clamp 4. Tangent and clamp 75