Created 14 June, 2017 

Marjorie Lee (Knibbs) PRATT, Archaelogical Consultant

The PRATT-MITCHELL Photo Turret

Marjorie Lee Knibbs was born in Chicago, Illinois. She and her husband Dr. Peter Paul PRATT were both Archaeological Consultants, operating a business called Pratt & Pratt Archaeological Consultants, Inc. between 1977 and 2012.

Recognising the difficulties of trying to accurately plot a single excavation unit such as a 5 foot or 2 meter square, various techniques to avoid distortion in mapping through the use of vertical photography including cameras mounted by way of balloons, kites, ladders held together by planks, bipods, tripods and tetra pods as well as other methods ranging from "cherry pickers" to one light-weight student armed with camera and precariously standing on the shoulders of a "mesomorph".
Marjorie's husband, working with a man named Grayson Mitchell, developed a new tetrapod turret, providing far greater flexibility than the Mayes turret which preceded it for photographing small excavation units.
The Pratt-Mitchell turret had telescoping legs, can be carried by two people and, because of the nature of its camera mount, the entire tetrapod need not be positioned plumb center over the excavation unit. Additional basics about the rig are that it extends to a maximum height of 17 ft. and is fitted with a unipod to which a camera may be attached. Ascending one side of the structure by means of a ladder (such as an aluminum 8 ft. extension ladder which extends to c. 16 ft.), the photographer can shoot directly above the excavation unit. Using a 35 mm. single lens reflex camera fitted with a 35 mm. wide angle lens or, using Polaroid Models 101, 102 or equivalent, the photographer can shoot from directly above a 5 ft. square and have no photographic distortion of the square at a height of 11 ft. At 17 ft. altitude it is somewhat easier to adjust the camera to avoid distortion. Furthermore, one can shoot a 2 meter square nicely at this elevation.

Peter acknowledge Marjorie's painstaking efforts of many days in the field and laboratory in helping us see to it that this piece of equipment proves itself a worthwhile scientific instrument.


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