REVIEWS 
ELECTRICITY.* 
N O branch of experimental science has passed more decidedly from its 
first or inductive stage into its second or computative, during 
the last thirteen years, than that of Electricity. Many who studied it 
lovingly and with appreciation at the former period will admit with willing- 
ness their obligations to the original Text-book of Dr. Noad, as well as to the 
bulkier Manual by the same author which preceded it. It was at the time 
singularly complete and exhaustive. In the preface, dated from the School 
of St. George’s Hospital, in September 1868, its precise position in the 
chronology of physics is accurately dated, by the cordial acknowledgment 
accorded to that “ beautiful electrical instrument invented by Professor 
William Thomson, E.R.S., namely, his Portable Electrometer,” and by the 
prefatory note on the recovery of the first, and the successful laying of the 
second, Atlantic Cable. The preface reappears in Mr. Preece’s revised edition 
in contrast with the editor’s Introduction. In this he evidently, to a certain 
extent, grasps the progress since then. “ All sciences,” he says, u in their 
earlier stages excite the imaginary powers of the mind ” (a phrase which is 
probably intended to mean the imagination), a but in their later stages the 
calculating powers. The study of Electricity has been a fine sphere for 
hypothesis ; but it has now become a cultivated field for the exercise of the 
quantitative tendency of the mind ; ” — an obscure sentence which probably 
shadows forth the idea that from hypothetical, Electricity has, by increased 
mental cultivation, become computational. In the same rather hazy, jaunty, 
and unsatisfactory prologue, which occupies very little more than four pages, 
we are told that recent discoveries “ have rendered it an exact science,” 
and that, notwithstanding this fact , 11 theory has been as much as possible 
excluded ; first, because there really exists no theory of Electricity properly 
so called ; and secondly, because what theory there is is used more for illus- 
tration than for explanation ; ” statements which appear to be somewhat self- 
contradictory. 
A feeling of disappointment thus instinctively produced at the outset does 
* “ The Student’s Text-book of Electricity.” By Henry M. Noad, F.R.S., 
&c. A new edition, carefully revised, with an Introduction and additional 
chapters, by W. H. Preece, M.I.C.E., &c. Crown 8vo. pp. 615. London: 
Crosby Lockwood & Co., 1879. 
