416 
rOPULAIi SCIENCE REVIEW. 
ELECTRICITY* 
P ROFESSOR TYNDALL has here given us the notes of his Lectures on 
Electrical Phenomena and Theories, and we thank him for doing so. 
They are a very clear and remarkably concise account of the whole subject, 
from the earliest experiments to the latest period, and are yet extremely 
and remarkably clear. It would be impossible to give an abstract of a 
book which is in itself abstractive, but a reference to the chapter entitled 
tl Historic Jottings concerning the Electric Telegraph” will enable us to 
give an idea of the nature of the book. After Nicholson and Carlisle had 
discovered the decomposition of water by the galvanic current, Sommering 
and Professor Coxe about the same time proposed a system of telegraphy 
based on the discovery. In 1820 Oersted discovered the deflection of the 
magnetic needle. The relation of electricity to the magnetic needle was 
then worked at by several. It was worked at by Professor Ritchie of the 
Royal Institution, and in 1832 Baron Schilling constructed models of an 
apparatus, which were exhibited before the Emperors Alexander and 
Nicholas. The next step seems to us to have been taken by Steinheil, 
who in 1837 had established a system of wires about 40,000 feet long, con- 
necting various parts of the city of Munich ; and he discovered that the earth 
alone answers the purpose of the second wire, which need not therefore be 
employed. From this stage the progress of the invention is obvious. Cooke 
and Wheatstone entered into partnership, and from 1837 succeeded in intro- 
ducing the telegraphic system into England, from which time, of course, 
many improvements have been made. We have, however, taken sufficient 
from this little book to show its value, and we now close our notice with 
toe hope that our readers will think as we do about the matter. 
* u Notes of a Course of Seven Lectures on Electrical Phenomena and 
Theories,” delivered at the Royal Institution of Great Britain, April 28 
to June 9, 1870. By John Tyndall, F.R.S. London : Longmans, 1870. 
