In research of lighting for pedestrians, many experiments have been conducted to determine how changes in lighting affect the ability to make interpersonal evaluations. Here we consider an alternative approach, predicting performance using a model - Relative Visual Performance. The results show that face evaluation ability is affected by adaptation luminance and also by personal characteristics; observer age and skin tone of the observed person. While 2 lx is sufficient for a young observer to evaluate a Caucasian face, the typical situation in laboratory trials, higher illuminances are needed for older observers and for darker skin tones.
Sir, I have the pleasure to transmit to you the account of our observations at this place. James Hoy, our young observer, observed in the house, on the ground-floor, in the room with the house clock, with the 3.5 feet achromatic telescope with triple object glass; Lord Alemoor observed on the floor above, with the 18 inch reflector, and a watch that shewed seconds, set a few minutes before the transit began, and compared after each contact; I was in the observatory, where I used my own 2 feet achromatic telescope, a mathematical instrument maker counting seconds from the clock.
XLIV. An account of the late transit of Venus, observed at Hawkhill, near Edinburgh. In a letter to the Astronomer Royal, from James Lind, M.D. at Edinburgh. To which are added some remarks by the Astronomer Royal; and further particulars relative to the observations communicated in other letters
