ERRATA.

The reader is requested to make the following corrections:

Page 89, 8th line from the bottom, strike out reference letter p.

Page 137, Fig. 36, transpose the reference letters f1 and ƒ2, the former to the latter and the latter to the former place.

Page 158, 12th line from top, for Dullough read Bullough.

IN COURSE OF PUBLICATION:

A SERIES OF

TECHNOLOGICAL HAND-BOOKS.

I

UNDER THE GENERAL EDITORSHIP OF

H. TRUEMAN WOOD, B. A.,

SECRETARY TO THE SOCIETY OF ARTS.

N 1873 the Society of Arts instituted Technological Examinations-Examinations, that is, in the theory of certain specified trades. In 1879 these Examinations were transferred to the City and Guilds Institute for the advancement of Technical Training, and considerable alterations were made in the system. Immediately on the foundation of these Examinations it became evident that the good they could effect was but partial. They supplied a test for the artisan's theoretical knowledge, but they supplied no means by which such knowledge could be acquired.

Funds subscribed by the Cloth workers' Company enabled the Society of Arts to establish, or promote the establishment of, a few classes, on the model of the South Kensington Science classes. The system thus commenced was extended by the City Institute, and there are now about 120 classes at which instruction is given to students in preparation for the Examinations.

2

TECHNOLOGICAL HAND-BOOKS.

Thus the want of teaching has been, at all events partially, supplied.

But the establishment of the Technological Examinations rendered manifest another want besides that of instructors, and that was the want of books in which a workman belonging to any particular trade could obtain the information he required about the theory of that trade. Whether he wished to study for the Examinations by himself and there are many who are not in a position to attend classes-or whether he wished merely to gain the knowledge which would be, of all knowledge, most serviceable to him, or whether even he was attending a class and required a text-book to guide his studies in it, no such book was, in most cases, available for him. Many technical books are too costly, many more are of necessity written in a style unsuited for men who have had little or no scientific training, while, in many cases, no book at all exists which deals with the technology of the particular industry with which the student is connected.

So long as the number of candidates for the Technological Examinations was small, it seemed as if textbooks, intended mainly for their use, would hardly have secured a sufficient number of readers to justify their production; but the rapidly increasing number of candidates,1 is good evidence that a demand for such works exists and is growing.

These are the circumstances which have led to the preparation of the present series. It is intended eventually The total number in 1879 was 202; this grew to 803 in 1880, and there were reported in April last to be 2,500 candidates preparing for examination in May.

1