Procure a fresh bullock’s eye from the butcher, and carefully thin the
outer coat of it behind: take care not to cut it, for if this should
be done the vitreous humor will escape, and the experiment cannot be
performed. Having so prepared the eye, if the pupil of it be directed
to any bright objects, they will appear distinctly delineated on the
back part precisely as objects appear in the instrument we are about to
describe. The effect will be heightened if the eye is viewed in a dark
room with a small hole in the shutter, but in every case the appearance
will be very striking.