xiv PREFACE. 
written by Prof. Edward S. Dana, with the collaboration, in electrotechnics, of Prof. Thomas C. 
Mendenhall, and in many special points, particularly those touching upon mathematical theory, of 
Prof. Charles S. Peirce. Professor Dana has also contributed the definitions of mineralogical terms, 
including the names of all distinct species and also of all important varieties. He has been assisted in 
denning the names of gems and the special terms employed in lapidary work by Mr. George F. Kunz. 
The lithological definitions, as also all those relating to geology, mining, metallurgy, and physical geog- 
raphy, have been contributed by Prof. J. D. Whitney. Professor Peirce has written the definitions of 
terms in mechanics, mathematics, astronomy, and astrology, of weights and measures, and of the various 
names of colors. In the mathematical work the aim has been to define all the older English terms, and 
all the modern ones that can be considered to be in general use, or are really used by a number of 
English mathematical writers, but not all the numerous terms that may be found only in special 
memoirs. All English names of weights and measures, as well as many foreign names, have been 
entered, but, as a rule, those of the latter that are at once obsolete and not of considerable importance 
have been omitted. As regards chemistry, it has of course been impossible to include names of com- 
pounds other than those that have a special technical and practical importance. The chemical definitions 
have been written by Dr. Edward H. Jenkins, with assistance from Dr. Isaac W. Drummond in defining 
the coal-tar colors, the various pigments, dyes, etc., and the mechanical processes of painting and dyeing. 
The definitions comprehended under the head of general technology (including all branches of the 
mechanical arts) have been contributed by Prof. Robert H. Thurston, with the collaboration, in defining 
the names of many tools and machines, of Mr. Charles Barnard, and, in various mechanical matters which 
are closely related to the special sciences, of the gentlemen who have been named 
The mechanical above as of Prof. Mendenhall in describing electrical machines and appliances, of 
arts and trades. 
Prof. Dana and Prof. Peirce in describing physical and mathematical apparatus, of 
Prof. J. D. Whitney in describing mining-tools and processes, etc. The terms used in printing and 
proof-reading have been explained by Mr. F. A. Teall, with the aid of valuable contributions of material 
from Mr. Theodore L. De Vinne. Special assistance in collecting technological material has been received 
from Mr. F. T. Thurston, and, at particular points, from many others. 
The terms of the philosophical sciences have been exhibited very completely, with special reference 
to their history from the time of Plato and Aristotle, through the period of scholasticism, to the present 
day, though it has not been possible to state all the conflicting definitions of different philosophers 
and schools. The philosophical wealth of the English language has, it is believed, never 
The philosophical been so f ully presented in any dictionary. Both the oldest philosophical uses of English 
words and the most recent additions to the vocabulary of psychology, psycho-physics, 
sociology, etc., have been given. The definitions of many common words, also, have been prepared 
with a distinct reference to their possible philosophical or theological applications. The logical and 
metaphysical, and many psychological definitions have been written by Prof. Peirce. The same method 
of treatment has also been applied to ethical terms, and to those peculiar to the various sociological 
sciences. In political economy special assistance has been received from Prof. Albert S. Bolles, Mr. 
Austin Abbott, and others. Prof. Bolles has also contributed material relating to financial and com- 
mercial matters. 
In the department of doctiinal theology considerable difficulty has naturally been experienced in 
giving definitions of the opinions held by the various denominations which shall be free from partisan- 
ship. The aim of the dictionary has been to present all the special doctrines of the different divisions 
of the Church in such a manner as to convey to the reader the actual intent of those 
Theological and ec- who accep t them. To this end the Rev. Dr. Lyman Abbott, to whom this branch 
clesiastical terms. 
of the work has been intrusted, has consulted at critical points learned divines of 
the various churches ; though, of course, the ultimate responsibility for the statements made in the 
dictionary on these and other theological matters rests with him and with the editor-in-chief. Aid 
has been obtained in this manner from the Right Rev. Thomas S. Preston, the Rev. Dr. William 
R. Huntiugton, the Rev. Dr. Daniel Curry, the Rev. Dr. Frederick W. Conrad, and others. Besides the 
