The Cayce Etheronic Device as Developed by Dr. Paul Cold (#440). This is the device described in the 440 readings (the 'science readings') also mentions readings 442 and 443. The book contains text of readings, schematics, drawings and photocopies of photographs. The book is exceedingly rare, copied from one of two copies known to exist. One of those two originals has been in my archives since acquired by gift in 1987.