Fig. 9 shows a globe filled with water, to be used at night to concentrate
the light on to the work. The light of the lamp is directly behind the
globe. A bull’s-eye lens can be used as a substitute and is equally good.
It is well to shield away by brown paper fixed to the top of the globe, or
other means, all light that does not fall on the block. It is most
unrestful to look up from work into the direct glare of a lamp; to work
without a globe or bull’s-eye with artificial light produces great
eye-strain and bad work. Good light is essential at all times.
[Fig. 10]