disturbed). Last is the STRENGTH OF INTER- SECTION, which generally means that the angle between two tie lines should be as close to 90° as possible.  The  more  acute  or  obtuse  the  angle  is between tie lines, the less accurate the location of the  point  defined  by  their  intersection. IDENTIFYING  PARTY  PERSONNEL A  typical  transit-tape  survey  party  contains two   chainmen,   a   transitman,   a   recorder (sometimes the transitman or party chief doubles as recorder), a party chief (who may serve as either instrumentman or recorder, or both), and axmen, if  needed.  The  transitman  carries,  sets  up,  and operates  the  transit;  the  chainmen  do  the  same with the tapes and the marking equipment. When the transitman turns an angle, he calls out  the  identity  and  size  of  the  angle  to  the recorder, as “Deflection angle AB to BC, 75°16´, right.” The recorder repeats this, then makes the entry. Similarly, the head chainman calls out the identity and size of a linear distance, as “B to C, 265.72 ft,” then the recorder repeats this back and makes the entry at that time. If the transitman closes  the  horizon  around  a  point,  he  calls  out, “Closing  angle,  such  and  such.”  The  recorder repeats this and then adds the closing angle to the original  angle.  If  the  sum  of  the  angles  doesn’t come   close   to   360°,   the   recorder   notifies   the party  chief. The  party  chief  is  in  complete  charge  of  the party and makes all the significant decisions, such as the stations to be marked on the traverse. ATTAINING  THE  PRESCRIBED ORDER OF PRECISION The  important  distinction  between  accuracy and  precision  in  surveying  is  explained  as  follows: l Accuracy denotes the degree of conformity with a standard. It relates to the quality of a result and  is  distinguished  from  precision,  which  relates to  the  quality  of  the  operation  by  which  the  result is  obtained. The accuracy attained by field surveys is the product of the instructions or specifications to be followed in doing the work and the precision in following  those  instructions. For  example,  the  “accuracy  of  a  surveyor’s tape”  means  the  degree  to  which  an  interval  of 100 ft, as measured on the tape, actually agrees with the exact interval of a standard 100-ft tape. If  a  tape  indicates  100  ft  when  the  interval  it measures  is  only  99.97  ft,  the  tape  contains  an inaccuracy of 0.03 ft for every 100 ft measured. The accuracy of this particular tape, expressed as a fraction, is 0.03/100, or approximately 1/3,300. l  Precision denotes degree of refinement in the performance of an operation or in the state- ment  of  a  result.  It  relates  to  the  quality  of execution  and  is  distinguished  from  accuracy  that relates  to  the  quality  of  the  result.  The  term precision  not  only  applies  to  the  fidelity  of performing  the  necessary  operations  but,  by custom, has been applied to methods and instru- ments  used  in  obtaining  results  of  a  high  order of  accuracy.  Precision  is  exemplified  by  the number of decimal places to which a computation is carried and a result stated. In a general way, the  accuracy  of  a  result  should  determine  the precision  of  its  expression.  Precision  will  not  have significance  unless  accuracy  is  also  obtained. If you measure a linear distance with a tape graduated  in  feet  that  are  subdivided  into  tenths, you  can  read  (without  estimation)  only  to  the nearest  tenth  (0.1)  of  a  foot.  But  with  a  tape graduated  to  hundredths  of  a  foot,  you  can directly read distances measured to the nearest hundredth  (0.01)  of  a  foot.  The  apparent  nearness of  the  second  tape  will  be  greater;  that  is,  the second  tape  will  have  a  higher  precision. Completely  precise  measurement  is  impossible in the nature of things. There is always a built-in or  inherent  error,  amounting  to  the  size  of  the smallest  graduation.  Precision  for  the  first  tape above,   expressed   as   a   fraction,   is   0.1/100   or 1/1,000  and  for  the  second  tape,  1/10,000. Precision in measurements is usually expressed in a fractional form with unity as the numerator, indicating the allowable error within a certain limit as indicated by the denominator, such as 1/500. In  this  case,  you  are  allowed  a  maximum  error of 1 unit per 500 units measured. If your unit of measure is in feet, you are allowed 1 ft for every 500 ft. In general, any survey has to be carried out accurately, meaning that errors and mistakes have to be avoided. The precision of a survey, however, depends upon the order of precision that is either specified  or  is  implied  from  the  nature  of  the survey. The various orders of precision are absolute, not relative, in meaning. Federal agencies control surveys.  They  are  generally  classified  into  four orders  of  precision;  namely,  FIRST  ORDER, SECOND   ORDER,   THIRD   ORDER,   and 13-21