XLIII Scientific Instrument Symposium - SIC 2024

Session Chair: Richard Kremer (Dartmouth College, USA)

Man, Machine or both? Reconsidering the precision of stereoscopic rangefinders
Author: Andreas Junk
The precision of rangefinders can be considered to be depending from the components of the instruments, which are used for distance measurements. This is particularly true for rangefinders as devised by Pacecco ab Ucedos (1762) or Georg Brander (1781). But those instruments are developed to be in a state, where a more or less untrained observer can easily adjust the settings and make a readout of the result. What if the operator with his unique set of experiences and training becomes a part of the instrument? Or maybe even worse: what if the operator's physiological limits also set an operational limit for the instrument?

The stereoscopic rangefinder of the Zeiss company, first presented as a measurement concept in 1899 on a model provided by the then-deceased Hector de Grousilliers, is based on Helmholtz's telestereoscopic design from 1857 and works with stereoscopic triangular distance marks. For both of these reasons, the operator's physiology plays an important role in determining a correct readout of the distance. Hence the question arises, if an instrument, which is prone to the imperfections of its human operator, can be considered a precision measurement device.

When precision is not a virtue: three forensic science objects where persuasiveness is the most important metric.
Author: Kristen Frederick-Frost
Three artifacts—a display of arsenic tests from the 1872 trial of Lydia Sherman, John Larson’s 1921 cardio-pneumo-psychogram for lie detection, and a sexual assault examination kit from the early 1980s—used precision in process, presentation, and procedure to validate investigative analyses. We can also consider how these objects were not just tools of systematic study but products of their maker’s beliefs about what was needed to make their work convincing beyond the science itself.

Professor George Frederick Barker’s shotgun approach to the presentation of arsenic tests invites us to think about how a previous poisoning case featuring warring medical experts created a perceived need to give the jury multiple types of chemical analyses for several victims. John Larson’s lie detector had to balance perceptions of two different audiences—that of the suspect and that of the fact finder. For the former, Larson needed to create an emotional response, ideally a suspect’s fear and anxiety. For the latter, Larson wanted to create an objective paper record that stood on its own outside of an interrogation. And the Vitullo sexual assault kit found acceptance because one of its creators, Marty Goddard, immersed herself in the reticence of police and medical professionals alike to investigate these crimes. The contents of this early kit, as well as those that follow, represent a negotiation between what various communities found necessary and worthy.

Each of these objects is a manifestation of a maker’s desire to be more than precise. They wanted to be persuasive.

Post-Earthquake Pioneer: The Application of the Low Altitude Remote Sensing System on Unmanned Aerial Vehicle
Author: Zhao Ke
Co-Authors: Congting Hao, Deli Chen
On May 12, 2008, a powerful earthquake at 8.0 Ms hit Wenchuan, a mountainous area in western Sichuan, China. Nearby, amounts of “quake lakes” formed by severe landslide, threatening the people living downstream. On May 13, the University of Electronic Science and Technology of China assembled a volunteer group with six institutions. They brought a low-altitude remote sensing system on Unmanned Aerial Vehicle (UAV) to Wenchuan to help. The UAV was capable of a 200-kilometer range in two hours, with wooden structure and a 38cc gasoline engine. The remote sensing instrument could take 0.2 m solution photos from 1000 meters above. They inspected the landslide dam-created Tangjiashan Lake, providing the data and rendered photo to the Prime Minister as a command. It helped the government to take measures to discharge flood from the dam bursting and evacuated people from downstream Mianyang City with a 5 million population. During 12 days, they detected over 100 rivers with the instrument, and gathered data of 34 risky lakes.

This study traces the instrument’s historical application in disaster contexts. Although the remote sensing instrument lacked groundbreaking technological innovations, its practicability surpassed other counterparts. In metrology, advancing both frontier research and translating it into engineering products is paramount. The system's deployment underscores the pivotal role of precision scientific instruments in informing decision-making during crises, emphasizing the necessity for a dual focus on theoretical advancement and practical application in scientific research.