Chapter I: THE PHILOSOPHY OF INVENTION, considered strictly in relation to

Ingenious Contrivances tending to facilitate Scientific Operations,
to extend Manufacturing Skill, or to originate New Sources of
Industry.--II. THE RIGHTS AND WRONGS OF INVENTORS, Legally and
Politically Examined.--III. EARLY INVENTORS' INVENTORIES OF SECRET
INVENTIONS, employed from the 13th to the 17th Century, in
substitution of Letters Patent.

"The author enters fully and effectually into the claims and grievances of the inventor. He discusses the arguments for and against the concession of patent right, and examines very ably leaders in the _Times_ on patent monopoly; very clearly dissipating the sophism of the opponents of patent right; also Sir William Armstrong's evidence regarding 'patent monopoly,' &c., affording an interesting and useful publication from its many excellences."--_The Scientific Review_, September 2, 1867.

"The second part of the volume discusses the right of inventors to a property in their inventions, and thus raises the question of the patent laws, and the twofold issue, whether it will be better to retain them and reform them, or to sweep them away altogether. We are bound to admit that he treats this topic in a fair spirit, and without any taint of bigotry. Mr. Dircks is a man whose opinions are entitled to a hearing."

_The London Review_, September 21.

"Mr. Dircks treats the real problem and discusses the comparative merits of the existing system, and the advantages which he, together with many others, hopes would follow on the establishment of some judicial council of inventions. The difficulties of the question are enormous, and no one will think the less of them after having gone through this volume.

"The third part, or the lists of their inventions left by many great and some ingenious persons, is interesting and curious."

_The Westminster Review_, October.

* * * * *

One Volume, post 8vo., price 3_s_ 6_d_,

A BIOGRAPHICAL MEMOIR OF
SAMUEL HARTLIB,
MILTON'S FAMILIAR FRIEND,

With Bibliographical Notices of Works published by him; and a reprint
of his Pamphlet entitled

"AN INVENTION OF ENGINES OF MOTION."

"Mr. Dircks's is the first careful attempt to make posterity his (Hartlib's) friend."--_The Examiner_, 18th February, 1865.

"A scholar-like little monograph, giving all the information that can be given about a man whose name occurs in the correspondence of almost every eminent literary or scientific person of the time of the Commonwealth."--_The Spectator_, 20th May.

* * * * *

One Volume, post 8vo., with engravings, price 2_s_,

THE GHOST!

AS PRODUCED IN THE SPECTRE DRAMA,

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)