Ada Goodrich-Freer, writing as "Miss X," published several good essays on scrying, some of which were reprinted in her Essays in Psychical Research (1899). See especially chapters III and V there. One can download that book of hers at http://iapsop.com/ssoc/1899__goodrich-freer___essays_in_psychical_research.pdf
She also contributed (anonymously) a paper, "Recent Experiments in Crystal Vision," to volume V (1889) of the Proceedings of the Society for Psychical Research, as well as several shorter pieces to the four volumes of the short-lived periodical, Borderland.
Re: study recomendations
https://archive.org/details/besterman-1924-crystal-gazing
Ada Goodrich-Freer, writing as "Miss X," published several good essays on scrying, some of which were reprinted in her Essays in Psychical Research (1899). See especially chapters III and V there. One can download that book of hers at
http://iapsop.com/ssoc/1899__goodrich-freer___essays_in_psychical_research.pdf
She also contributed (anonymously) a paper, "Recent Experiments in Crystal Vision," to volume V (1889) of the Proceedings of the Society for Psychical Research, as well as several shorter pieces to the four volumes of the short-lived periodical, Borderland.
You can find volume V of the Proceedings at
https://archive.org/details/proceedingsofsoc05soci/page/n4/mode/1up
and all the volumes of Borderland at
http://iapsop.com/archive/materials/borderland/