Gridding and Triangulation

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Gridding T-26

In the closing days of 1989, the decision was made to leave two lines of meter markers in place, contrary to the usual practice. This double line was used to grid T-26. One line, dividing meters J-K forma the northern extenct of expected excavtiona, The other line, running 2 meters off the upper building, dividng meters B-C will be used to extend the trench northewards if necessary. North-South extensions off J-K were accomplished by standard trangulation. These measurements will be examined for accuracy on the arrival of the architect.

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Notes On Grid:

In the years previous to the 1989 excavations, miscalculations on the gridding of T-26 were made. In the 1989 excavation season, notes were placed in the day books of previous years noting this problem. Beyond a miscaculation of meter notation (i.e. meter n1 being called n2) a disorienctation N-S/E-W was also a problem, as old bauble lines were oftern used to grid out new trenches. While 1989 excavations tried to correct all these problems, there still exista a disorientation along the L-M line. As one moves east, the shift may reach int he N meter. It is expected that 1990 excations in, meters 64-71 will correct this problem for the area, but it will persist to the east anf have to be monitered.

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T-26 Trangualtion measurements

K-L(M)/65-70

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Notes on Elevations:

Picchetto marking SE corner of J/65 has has a line level attached. String attached at 24 cms. above surface.  Depths in this book will generall be recorded as n cm b.d. B.D. = below datum, i.e. the depth below the line level.* For the prupose of making find tags to accopmany finds down to the magazzino, I record levels as n cm. b.s. B.S. = below surface as determined by the nearest bank or surface. This is donw so that these tage will correlate easily with taga made by others. Interms of absolute depths that can be related accross the site, my b.d. measurements are the more accurate.

*N.B.  The architect sighted the datum point J/65 at 27.86 M above the fixed points established for the Upper Building.

* not the depth below the soil surface but the depth below the string

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Bank Cleaning T-26

Film 1990-1