POPULARLY ILLUSTRATING THE MARVELLOUS OPTICAL ILLUSIONS OBTAINED BY THE APPARATUS CALLED THE DIRCKSIAN PHANTASMAGORIA. "Mr. Dircks gives us the benefit of all his progressive discoveries in the matter, from the paper first read at the British Association Meeting at Leeds, in 1858, to the more recent improvements, with full explanations of the machinery, apparatus, and processes adopted in these ghost dramas, and further favours the public with a number of new adaptations. As a curious description of these spectral illustrations, the book is most interesting."--_The Technologist_, January, 1864. "A volume explanatory of the uncommonly clever and scientific "spectral illusion" which has of late fairly turned the public head." _The Dublin Builder_, January 1. "A few months ago all London was rushing off to see Professor Pepper's Ghost, as it was called, but which it now appears was the property of Mr. Dircks, and from which his good name was filched in a very unhandsome manner. Here then he tells us all about it, how the spectre was raised, and how we may ourselves at pleasure call spirits from the vasty deep."--_The Bookseller_, February 29. * * * * * Transcriber's Notes Page 36: changed "Sorbiere" to "Sorbière" (15. Samuel Sorbière visited the works at Vauxhall) Page 61: changed "Jupiper" to "Jupiter" (of cloves, &c. to Jupiter;) Page 83: changed "BD^2" to "BG^2" ({AG^2 + CB^2 + 4(OF^2)} = {AC^2 + CG^2 + BG^2 + AB^2.}) Page 83: changed "sqrt(10^2 5^2)" to "sqrt(10^2) + 5^2" ( ... = {5^2 + sqrt(10^2) + sqrt(10^2) + 5^2,}) Page 84: changed closing parenthesis to closing braces ( ... 9} = {25 + 10 + 10 + 25} = 70) Page 84: changed "tangental" to "tangential" (tangential to the circle X) Page 84: changed "Q" to "2" (making G _n_ equal to 2AG - GD) Page 84: added missing opening parenthesis in "(I have indicated this square by dotted lines.)" Page 84: changed "+ 1'25}" to "× 25" ({76'5625 + 1'5625} = {3'125 × 25}) Page 84: changed "hypothenuse" to "hypotenuse" (the area of a square on the hypotenuse) End of the Project Gutenberg EBook of Scientific Studies, by Henry Dircks