Below is a high resolution version of the famous Tricorder image seen in the 1968 book “The Making of Star Trek” by Stephen Whitfield and Gene Roddenberry; followed by some rare additional photos of this same piece and a screenshot testifying to its use in the highly acclaimed TOS episode “The City on the Edge of Forever”.
Next, a modern photo of the TOS Tricorder seen in “Day of the Dove”; and a screenshot from that episode.
When the modern day image of the Day of the Dove (DD) Tricorder is rotated; it appears in a very similar orientation spatially as The Making of Star Trek (TMOST) Tricorder; which facilitates measurement analysis. In the following composite photo, both pieces are presented in the same scale – so that a single common reference distance known to be identical on the 2 props is set to be equal. CAD software is then used to generate measures on a series of other comparable geometries to provide insight into the normal size variations to be expected when encountering authentic TOS Tricorder hand props.
Note: The units listed on the photo below are not precise reflections of the actual prop dimensions in either British or Metric units; they were derived by taking an exact measure in Inches and applying a scaling factor – however, the distances listed are sufficiently close to Inches that a discussion of variation in the next paragraph which makes reference to Inches is still accurate.
It can be seen that several measured distances, such as the thickness of the aluminum plates used to construct the side frames and large cross member on the two pieces; as well as the diameters of the indicator light bezels and control knobs – are identical on both Tricorders. However, significant variation is observed in the cutouts for the microphone and viewscreen on the main control panel faceplate; and the height and width measurements of the main bodies for these two screen-used pieces are seen to vary by as much as a quarter of an inch. Unlike communicators, whose main body consisted of a single vacuuformed shell; Tricorders were much more complex assemblies subject to the cumulative length differences in hand-cut cross members, screwed in shell attachments, and differently aligned vertically mounted hood assemblies, etc. Even layers of leatherette covering present on some pieces but excluded on others would generate a measurable difference in component thickness.
The following image shows two other authentic TOS Tricorders photographed in the home of Star Trek Set Decorator John Dwyer; which are now part of the Allen and Gurian collections. In the composite photo afterwards, the Gurian Tricorder has been positioned to replicate the orientation of the Allen piece shown above it to facilitate another measurement study. (Note: My dog insisted in being a part of the second photo.)
Interestingly, the overall measured height and width differences between these two pieces are only approximately one-tenth of an inch or less apart; which is significantly less than that observed between the TMOST and Day of the Dove pieces.