Lacaille, who made more observations than all his contemporaries put
together, and whose researches will have the highest value as long as
astronomy is cultivated, had an observatory at the Collège Mazarin,
part of which is now the Palace of the Institute, at Paris.
For a long time it had been without observer or instruments;
under Napoleon’s reign it was demolished. Lacaille never used
to illuminate the wires of his instruments. The inner part of
his observatory was painted black; he admitted only the faintest
light, to enable him to see his pendulum and his paper: his left
eye was devoted to the service of looking to the pendulum, whilst
his right eye was kept shut. The latter was only employed to look
to the telescope, and during the time of observation never opened
but for this purpose. Thus the faintest light made him distinguish
the wires, and he very seldom felt the necessity of illuminating
them. Part of these blackened walls were visible long after the
demolition of the observatory, which took place somewhat about
1811.--_Professor Mohl._