Bradley Fiske defends his book

Lieut. Fiske's Defense of His Book on Electricity.

To the Editor of The Electrical World:

SIR: Referring to the review of my book by Mr. Theo. F. Jewell, it occurs to me that, in view of the evident ability of its author and the soundness of most of his views on abstract points in electrical science, a few comments upon some of his strictures may not be out of order. The fact that his review is, on the whole, so highly complimentary gives additional force to his adverse criticisms upon special points; yet some of these seem hardly pertinent.

In the first place, I think Mr. Jewell has failed to appreciate the fact that most of the men interested in electricity have not an advanced education in physics. In my book I have endeavored to show to practical men the practical bearings of a very abstruse and intangible science. It was essential, therefore, to sacrifice occasionally mathematical nicety of definition. In mathematics, we frequently adopt an approximation, simply because it may be for our practical purpose; just as useful as a more complicated, though more exact, expression, and much more manageable.

In trying to show what "potential" is and what " electrical units" are, I tried to avoid words not ordinarily used in practice. Being compelled to explain the meaning of "dyne" and "erg," I purposely avoided talking of "force" and "acceleration." How many men know what force is? The great physicists of Europe are perpetually wrangling over it. Everybody, however, has a clear idea of weight. We express the force upon a piston in pounds, and we call a pound a weight. Was it not better, then, in a practical book to call a dyne a weight than to go into a long explanation about "acceleration," "mass," ''force," etc., which would have confounded nine in ten of my readers? The editor of this paper has suggested that it would be better, however, to say a dyne is equivalent to 1/981 gramme, than to say it is 1/981 gramme. This suggestion is good and will be followed in the next (third) edition.

Mr. Jewell disapproves also of my explaining the idea of "work" by beginning with an illustration of lifting a weight against gravity. Can an illustration giving a better idea to practical men be devised ? Moreover, I show distinctly in the context that work is done similarly against other forces as well. I also show that a dyne measures other forces than that of gravity.

Have I mixed up potential and potential energy, as Mr. Jewell says ? I think that most men would understand from my book that potential is measured in terms of the work done on a unit. Mr. Jewell explains his meaning by a reference to the units of mass, gravity and height (m. g. h). This he is at liberty to do; but I was clearly restricted from the use of those quantities. While they form the basis of measurement in all the physical sciences, they would have hopelessly mystified the practical men whom I desired to reach. Being under the necessity of explaining abstract things to practical minds, I sometimes had to use several sentences when one sentence with the usual scientific terms would have been enough for scientific minds. I think Mr. Jewell has occasionally got a wrong idea of the meaning of a sentence by separating it from the context.

Mr. Jewell says: " Electromotive force is not force at all." Does he know this? Does anybody know this? Suppose even that electricity is not matter. Electromotive force may not then be a mechanical force; but can Mr. Jewell, or any one else, assert that there is no force except mechanical force? He seems to argue that conductors oppose resistance to the passage of electricity. What, then, tends to send electricity through conductors if it be not force of some kind? Does not the idea of electrical resistance necessitate the idea of electromotive force?

I have endeavored to find a place in my book in which I say that it '"requires a greater E. M. F. to overcome a great resistance than a small one," but cannot find it; but I find a place in which I say that in any simple circuit a greater proportion of the whole E. M. F. of the generator is expended in overcoming the great resistances than the small ones.

Mr. Jewell's objection to my explanation of strength of current, seems curious as there can be no doubt that, if we add cells in series to the one cell originally in a circuit, the current will be increased, unless, indeed the resistance of the conductor be zero — an impossibility. This fear that my explanation would convey the idea that current will always be increased by adding cells in series would not seem very well based after reading the arithmetical examples that followed my statement.

A description of Dolbear's telephone and the induction balance would doubtless have been most interesting; but the purpose of the book forbade the description of apparatus not in extensive practical use.

BRADLEY A. FISKE,

WASHINGTON, Dec. 10, 1888.