Why did Henry Cavendish place the torsion balance in a sealed room?

Henry Cavendish placed the torsion balance in a sealed room to isolate the apparatus from external disturbances.1

He recognized that the gravitational force he intended to measure was extremely tiny, and even minor environmental factors—such as differences in air temperature—could create disturbances that would swamp the measurement. By sealing the room and observing the balance through a telescope from the outside, Cavendish ensured the accuracy of his results, allowing him to successfully determine the density of the Earth.1