418 
POPULAR SCIENCE REVIEW. 
TELEGRAPHY. * 
T HIS is essentially a working book, and its value in this capacity may be 
appreciated from the fact that it is now in its seventh edition. 
The telegraphs in Great Britain and Ireland having now passed into the 
hands of the State, a sketch of the history of the system is given by way of 
introduction. 
This notes the joint patents of Cooke and Wheatstone in 1837, which first 
demonstrated the practicability of the plan on an experimental circuit between 
Euston and Camden Town, followed in the next year by an actual working 
telegraph between Paddington and West Drayton. These patents were 
purchased by the Electric and International Company, incorporated by Act 
of Parliament in 1846, but for several years proved to be pecuniarily un- 
profitable. 
At first the double needle was used for the more important circuits, the 
single for the less important. 
The former was superseded by Bain’s chemical recorder, and this in turn 
gave way to Morse’s ink-writer, the single needle holding its place in con- 
sequence of the ease with which it is kept in order. 
The magnetic instrument was found to be laborious in manipulation. 
Bright’s bell instrument leaves the hands free for writing the message. The - 
United Kingdom Company used the Morse and Hughes’s systems only. 
The first six chapters, occupying 113 pages, are devoted to the laws of 
electricity generally; the seventh and eighth, amounting to 132 pages, 
explain construction and modes of testing. Part IX. is concerned with 
apparatus, relays, duplex working and Hughes’s instrument ; Part. X. with 
submarine telegraphy; Part XI. with automatic telegraphs which record 
their signals ; the twelfth and last section with recent inventions, the tele- 
phone and the quadruplex system. 
Valuable tables of logarithms, measures, constants, guages and coefficients 
conclude a very practical work. The text is illustrated with abundant 
figures and diagrams ; and simple numerical examples are introduced freely 
wherever they are needed. 
NYTIIING Captain Abney may publish on the subject of Photography 
is sure to be of value. The present work is stated to be supplemented 
by that on “ Instruction in Photography,” by the same author ; it having 
been found impossible to compress the necessary matter into a single volume. 
* “A Handbook of Practical Telegraphy,” by R. S. Culley. Seventh 
Edition, revised and enlarged. London : 8vo. pp. 468. Longmans, 1878. 
f “ A Treatise on Photography,” by W. De Wiveleslie Abney, Captain 
R.E., F.R.S., &c. : sm. 8vo. pp. 326, London : Longmans, 1878. Text-books 
of Science. 
W. H. Stone. 
PIIOTOGRAPIIY.t 
