J. J. Thomson\u27s Theory of Matter

J. J. Thomson\u27s theory of matter is largely the outgrowth of his own experimental researches in the nature and structure of electricity. In reading the records of his work it is often hard to discriminate in just what sense he uses the term electricity. It is certainly not well defined whether the term stands for primordial energy or matter

Nucleations According to Barus

No doubt all students of science have read more or less about Barus\u27 work on condensation phenomena as produced in a specially constructed fog chamber. As is known, his work has been done under the direction of the Carnegie Institution of Washington, founded particularly for the solution of research problems, involving much time and considerable expense. The prime purpose of his work, so far as I can interpret it, is to determine the part played by various kinds of nuclei in the atmospheric condensation of vapor. This, of course, is a very interesting problem to the student of physiography, as well as to the physicist

Mutual Induction and the Internal Resistance of a Voltaic Cell

The usual method of making a rapid determination of the internal resistance of a voltiac cell, primary or secondary, is by means of the condenser in circuit with a ballistic galvanometer. The deflection of the galvanometer due to the discharge of the condenser is first taken on open circuit with the cell and again when the cell is on a closed circuit the known resistance. The working formula is r=d—d1 over d1xR, in which d and d1 are the different deflections of the galvanometer needle and R is the external resistance of the closed circuit. The explanation of this method can be found in Carhart and Patterson\u27s Electrical Measurements

Determination of the Charge of an Electron by Wilson\u27s Method, using Radium

The following discussion of the experimental determination of the charge e of an electron may prove interesting inasmuch as the conditions of the experiment were in many respects more favorable than those of previous attempts. As is generally known, determinations of e have been made by J.J. Thomson and H.A. Wilson at the Cavendish-laboratory, England. Their methods were quite different, although both obtained their data from observations of ionized clouds produced by the rapid expansion of supersaturated air in a fog chamber

A Convenient Voltaic Cell

I wish to discuss briefly a convenient form of the Lalande class of voltaic cells for which the government has recently allowed me a patent. While the cell possesses nothing startling in its newness, it yet has those advantages which make it better, I think, than any other for the purpose for which it was devised

The Magnetic Effect of an Electric Current

From a practical point of view, the magnetic property of an electric current is of great value to man. It is this property that is utilized in the dynamo for the generation of large currents of electricity. It is also this property that enables man to utilize the driving power of the electric motor in the manufacturing industries

Mechanics of Solids

According to the traditional arrangement of subject matter in textbooks on high school physics, it is customary to introduce the treatment of mechanics of so-lids by beginning with the subject of motion, force, and Newton\u27s laws of motion. This at once leads the immature student into a labyrinth of abstract conceptions that is generally disheartening. It would show better judgment on the part of the teacher to begin the subject of mechanics with material that is more concrete to the student and which is continually before him in his environment

The Simple Machines

With reference to a pulley system, the work equation is clearly discerned in its practical operation. In presenting the pulley, the writer uses a rectangular frame about two feet high and three feet wide. A number of hooks are screwed into the top cross piece of the frame. With such a device a number of different pulley combinations can be shown at one time

Atmospheric Pressure

Having learned the meaning of pressure from the study of hydrostatics, the pupil is easily led to understand the striking phenomena of atmospheric pressure. He should readily appreciate that the term refers to the gravity pressure of the atmosphere

Hydrostatics

The classroom apparatus necessary for an effective, interesting presentation of hydrostatics includes: pressure tubes, manometer tubes, pressure syringe, Pascal\u27s vases and equilibrium tubes. All of these are listed in the apparatus catalogs found in every high school