Resistance of the external circuit.  R_{o}
Intensity in the armature.  C_{a}
Intensity in the coils of the magnet.  C_{m}
Intensity in the external circuit.  C_{e}
Coefficient of self-induction.  L_{s}
Coefficient of mutual induction.  L_{m}

A primary battery would be represented as in Fig. 1, and a battery of accumulators as in Fig. 2.

[Illustration:  FIG. 1.]

[Illustration:  FIG. 2.]

In order to designate incandescent lamps, circles would be used, and stars for arc lamps.  A system of incandescent lamps arranged in multiple arc would be represented as in Fig. 3.

[Illustration:  FIG. 3.]

Fig. 4 and the formula

R = B + Gs/(G + s) + r

would serve for the total resistance, R, of an electric circuit, upon giving the letters the significations adopted.

[Illustration:  FIG. 4.]

Such is, in brief, the present state of the question.  The scientific bodies that have taken hold of it have not as yet furnished a fully co-ordinated work on the subject.  Let us hope, however, that we shall not have to wait long.  The question is of as much interest to scientific men as to practical ones.

A collection of identical symbols would have the advantage of permitting us to abridge explanations in regard to the signification of terms used in mathematical formulas.  A simple examination of a formula would suffice to teach us its contents without the aid of tiresome explanatory matter.

But in order that the language shall be precise, it will be necessary for the words always to represent precise ideas that are universally accepted, and for their sense not to depend upon the manner of understanding the idea according to their arrangement in the phrase.

Nothing can be more desirable than that the societies of electricians of all countries shall continue the study of these questions with the desire of coming to a common understanding through a mutual sacrifice of certain preferences and habitudes.—­E.  Dieudonne, in La Lumiere Electrique.

* * * * *

IMPROVED MICROSCOPICAL SETTLING TUBE.

By F. VANDERPOEL, of Newark, New Jersey.

In the February number of this Journal the writer described a new settling tube for urinary deposits which possessed several advantages over the old method with conical test-glass and pipette.  For several reasons, however, the article was not illustrated, and it is for the purpose of elucidation by means of illustration, as well as to bring before the readers of the Journal two new and improved forms of the tube, that space in these columns is again sought.  The first two of the figures, 1 and 2, represent the tube as originally devised; 1 denoting the tube with