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Articles 13441 - 13470 of 14064
Full-Text Articles in Entire DC Network
The Theory Of The Two-Way Quincke Tube, G. W. Stewart
The Theory Of The Two-Way Quincke Tube, G. W. Stewart
Proceedings of the Iowa Academy of Science
The long known Quincke two-way tube has been assumed to eliminate transmission by interference only at a frequency corresponding to a difference of path of one-half wave length. The author has derived the theory of the action and finds that the ratio of transmitted to incident energy.
A New Analysis Of The Action Of Amsler's Polar Planimeter, George E. Davis
A New Analysis Of The Action Of Amsler's Polar Planimeter, George E. Davis
Proceedings of the Iowa Academy of Science
The theory of Amsler's polar planimeter, as commonly given, leads to the expression A= L h, where A is the area circumscribed, L is the length of the tracer arm, and h is the net distance of translation of the tracer arm in a direction perpendicular to its length. However, it can be shown that the area may also be given by A = L 2 ∅, where ∅ is the net angle through which the tracer arm has rotated about either of its ends. But as the tracer point passes around the area A, the tracer arm does …
The Dielectric Properties Of Some Crystals At Radio Frequencies, A. A. Aardal
The Dielectric Properties Of Some Crystals At Radio Frequencies, A. A. Aardal
Proceedings of the Iowa Academy of Science
An attempt has been made to study the dielectric properties of a few crystals at radio frequencies ranging between 50 and 3000 kilo-cycles per second. The properties studied are phase difference, dielectric constant, capacity, resistance, and power factor. It is found that the dielectric constant, the electrical capacity and resistance decreases with the increase in frequencies of electrical oscillation, and that the phase difference and power factor increase with increase in frequencies.
The Phosphorescence Of Fused Quartz, A. C. Bailey
The Phosphorescence Of Fused Quartz, A. C. Bailey
Proceedings of the Iowa Academy of Science
Experiments performed here corroborate the report of Drummond and Webster that fused quartz can be activated to phosphorescence by being irradiated with ultra violet light from a quartz mercury vapor lamp. It is also found that the fused quartz is thermoluminescent. The radiations emitted from the phosphorescent and thermoluminescent quartz appear to be confined largely, if not completely, to the visible region. These radiations, however, at ordinary room temperatures, are of such low intensity as to be invisible to the eye.
Fifty Years At The Teachers College, David Sands Wright
Fifty Years At The Teachers College, David Sands Wright
Iowa Book Gallery
A history of the Iowa State Teachers College, later known as the University of Northern Iowa.
In Memoriam: Philip Sprong; Walter Scott Hendrixson; Clyde Leslie Winter
In Memoriam: Philip Sprong; Walter Scott Hendrixson; Clyde Leslie Winter
Proceedings of the Iowa Academy of Science
No abstract provided.
The Address Of The President - The Ministry Of Science, R. I. Cratty
The Address Of The President - The Ministry Of Science, R. I. Cratty
Proceedings of the Iowa Academy of Science
We are living in a very progressive age - one which when compared with that of our forebears, is filled with advantages for our welfare and enjoyment that challenges the attention of every thoughtful person. That knowledge is power was never a more self-evident truth than it is today, and science, which is simply classified knowledge, is every day coming more closely in touch with human lives, and ministers to us in innumerable ways undreamed of a century ago. Just how great our debt is for all this it is difficult to say. Captain Roald Amundson, that modern Viking whom …
The Transference Numbers And The Degree Of Solvation Of The Ions Of Lithium Chloride In Certain Alcohols, J. N. Pearce, W. G. Eversole
The Transference Numbers And The Degree Of Solvation Of The Ions Of Lithium Chloride In Certain Alcohols, J. N. Pearce, W. G. Eversole
Proceedings of the Iowa Academy of Science
The low migration velocities of some of the ions of the elements of low atomic weight, as well as the many other phenomena that are not explained by simple electrolytic dissociation, have led to the belief that the ion does not lead an independent existence in the solution, but is solvated, or combined chemically with one or more molecules of the solvent.
Relativistic Reflections, Edward S. Allen
Relativistic Reflections, Edward S. Allen
Proceedings of the Iowa Academy of Science
An important result of the great interest in the theory of relativity has been that mathematicians and physicists on the one hand, philosophers on the other, have given increasing attention to each other's work. It may not, then, be out of place for one whose interest in the subject has been mainly on the mathematical side to examine some philosophical inferences which have been drawn from it.
Further Evidence Of The Effect Of Valence And Chemical Combination On The K Limit Of Sulphur, R. A. Rogers
Further Evidence Of The Effect Of Valence And Chemical Combination On The K Limit Of Sulphur, R. A. Rogers
Proceedings of the Iowa Academy of Science
A number of spectrograms have been obtained showing the K absorption limit of sulphur. The absorption was due to sulphur in the gypsum (Ca SO4. 2H2O) crystal used in the analysis of the M series absorption spectra of the platinum group.
A New Type Of Photoelectric Colorimeter, D. H. Palmer, Jay W. Woodrow
A New Type Of Photoelectric Colorimeter, D. H. Palmer, Jay W. Woodrow
Proceedings of the Iowa Academy of Science
A photoelectric colorimeter has been constructed which is capable of detecting small changes in the color of meat. With this apparatus it was possible to measure the variation in the color of meat as a function of the time of exposure to the air. The effects of temperature upon the color variation were also measured; and some data has been obtained showing the relation between the color and the grade of the meat.
The Moulding Action Of Surface Tension On A Free Sheet Of Water, L. B. Spinney
The Moulding Action Of Surface Tension On A Free Sheet Of Water, L. B. Spinney
Proceedings of the Iowa Academy of Science
A smooth stream of water falling vertically is allowed to strike the center of a small circular plate placed horizontally. The water under these circumstances spreads laterally over the edge of the plate in a thin stream. Under the action of gravity and surface tension this thin bubble-like stream assumes various forms determined by the velocity of the stream impinging upon the plate and the dimensions of the various parts of the apparatus. The bubble may be made to assume a more or less nearly spherical form or, by joining a free water surface below, to shape itself into the …
The Toxic Effect Of Ultra Violet Radiations Upon Yeast And Yeast-Growing Media, A. C. Bailey
The Toxic Effect Of Ultra Violet Radiations Upon Yeast And Yeast-Growing Media, A. C. Bailey
Proceedings of the Iowa Academy of Science
We have not found in our work any region of ultra violet energy which will produce a stimulation of yeast growth in any synthetic medium used. In every case the action of the ultra violet radiations has produced a toxicity in the media in proportion to the amount of ultra violet received. Even fifteen minutes of ultra violet light at 16 cm. from the lamp produced such a toxicity in the medium that the yeast count twenty-four hours afterwards was ten per cent below the control count.
A Vacuum Tube Tester For Routine Work Using Alternating Current, P. S. Helmick
A Vacuum Tube Tester For Routine Work Using Alternating Current, P. S. Helmick
Proceedings of the Iowa Academy of Science
Some form of vacuum tube tester is a necessity in every radio laboratory. The vacuum tube tester herewith described is the result of an effort to design a simple instrument suitable for routine work, and which could be left permanently connected to the lighting circuit thus being always ready for use.
Magnetic Properties Of Thin Films Of Iron, Electrolytically Deposited, E. P. T. Tyndall
Magnetic Properties Of Thin Films Of Iron, Electrolytically Deposited, E. P. T. Tyndall
Proceedings of the Iowa Academy of Science
Films of iron from 100 to 200 millimicrons thick deposited electrolytically from neutral and acid solutions of iron ammonium sulphate show a surprising magnetic hardness. At a field of 40 gauss the intensity of magnetization is from 200 to 300 c.g.s. units. No sudden increase in magnetization is found up to fields of 150 gauss. Films deposited on the initial film, using much smaller current densities than that required for the initial deposit, show the usual properties of electrolytic iron. An intensity of magnetization of 1000 is reached at 40 gauss field. The cause of the hardness of the initia1 …
Potentials Of Spark Lines Of Mercury Vapor, J. A. Eldridge
Potentials Of Spark Lines Of Mercury Vapor, J. A. Eldridge
Proceedings of the Iowa Academy of Science
It has been shown by a series of photometric readings on thirty spark lines of mercury falling in the range 2000-5000 angstroms, that these lines fall into three groups. (1) Excitation potential at about 20 volts, (2) excitation potential about 28 volts and (3) excitation potential about 55 volts. The exact values of these potentials are uncertain since they depend upon pressure and current conditions. If we accept the results of Smythe that double ionization occurs first at 20 volts and triple ionization certainly not under 100 volts we may suppose the first class of lines as due to the …
A Comparison Of Power Output Conical, Hyperbolic And Exponential Trumpets, G. W. Stewart
A Comparison Of Power Output Conical, Hyperbolic And Exponential Trumpets, G. W. Stewart
Proceedings of the Iowa Academy of Science
These measurements are presented as illustrative of the advances that have been made in the measurement of acoustic power. They refer of course to single cases, but they are of interest in showing the actual fluctuations of both components of impedance and of the power output in the three types of trumpets stated in the title.
Variation Of The Intensity Of The Spectral Lines Of Mercury With The Velocity Of The Exciting Electrons, W. D. Crozier
Variation Of The Intensity Of The Spectral Lines Of Mercury With The Velocity Of The Exciting Electrons, W. D. Crozier
Proceedings of the Iowa Academy of Science
A study has been made of the variation of the intensity of the spectral lines of mercury when excited by impact of electrons of controlled velocity. In accordance with some earlier observations by Dr. J. A. Eldridge, it is found that the lines divide into two classes. In one class the intensity of the line increases uniformly from zero to a certain limit as the velocity of the electrons increases above the minimum exciting velocity. In the other class the intensity rises rapidly to a maximum at a velocity not far above the minimum exciting velocity, and then decreases to …
Electricity And Mechanics, John A. Eldridge
Electricity And Mechanics, John A. Eldridge
Proceedings of the Iowa Academy of Science
When electric charges are in motion the forces between them differ from the electrostatic forces. The magnetic concept is used to take account of these non-electrostatic forces. The magnetic effect of a moving charge is relative to the electrostatic extremely small except when the velocity approaches that of light. However due to the circumstance that the electrostatic effects often, as in a wire carrying a current, practically cancel, the magnetic forces are very important. According to our present beliefs any field of force changes in an analogous manner if it be moved. There is theoretically the same excuse for speaking …
The Scattering Of X-Rays By Camphor, Roger M. Morrow
The Scattering Of X-Rays By Camphor, Roger M. Morrow
Proceedings of the Iowa Academy of Science
The ionization chamber method of analysis was used. A Soller slit placed between the scattering material and the x-ray tube, gives a wide beam of nearly parallel rays; one placed between the scattering material and the ionization chamber limits the angle of divergence of the rays and yet permits a wide beam to enter the ionization chamber. Thus a large sample of material could be used thereby increasing the intensity without any sacrifice of resolving power.
Fourier Analysis Of The Flow Of Electricity In Flat Plates, C. Leonard Albright
Fourier Analysis Of The Flow Of Electricity In Flat Plates, C. Leonard Albright
Proceedings of the Iowa Academy of Science
A Fourier analysis of the flow of electricity in a two-dimensional plate depends upon the solution of Laplace's equation in two dimensions. The problem considered in this paper is that of a rectangular plate, the potential being applied at two adjacent sides. The results of the experiment depended upon the finding of the equipotential lines. This was done by means of a dish forty centimeters wide and fifty centimeters long. Copper strips were placed on two adjacent sides. An ordinary storage battery was used as a source. The lines were then found by exploring the dish with the terminals of …
The Alumni News Letter, V9n4, October 1, 1925, Iowa State Teachers College
The Alumni News Letter, V9n4, October 1, 1925, Iowa State Teachers College
The Alumni News Letter
Contains news of the College and its alumni.
Summer Term Commencement [Program], August 20, 1925, Iowa State Teachers College
Summer Term Commencement [Program], August 20, 1925, Iowa State Teachers College
UNI Commencement Programs
The program of the commencement ceremonies, including a list of institutional leadership, a list of the departments by college, awards given at the ceremonies, and a list of undergraduate and graduate degree candidates.
The Alumni News Letter, V9n3, July 1, 1925, Iowa State Teachers College
The Alumni News Letter, V9n3, July 1, 1925, Iowa State Teachers College
The Alumni News Letter
Contains news of the College and its alumni.
Spring Term Commencement [Program], June 2, 1925, Iowa State Teachers College
Spring Term Commencement [Program], June 2, 1925, Iowa State Teachers College
UNI Commencement Programs
The program of the commencement ceremonies, including a list of institutional leadership, a list of the departments by college, awards given at the ceremonies, and a list of undergraduate and graduate degree candidates.
Thirty-Ninth Annual Meeting Of The Iowa Academy Of Science, May 1 And 2, 1925, Iowa Academy Of Science
Thirty-Ninth Annual Meeting Of The Iowa Academy Of Science, May 1 And 2, 1925, Iowa Academy Of Science
Iowa Academy of Science Documents
No abstract provided.
The Alumni News Letter, V9n2, April 1, 1925, Iowa State Teachers College
The Alumni News Letter, V9n2, April 1, 1925, Iowa State Teachers College
The Alumni News Letter
Contains news of the College and its alumni.
The Alumni News Letter, V9n1, January 1, 1925, Iowa State Teachers College
The Alumni News Letter, V9n1, January 1, 1925, Iowa State Teachers College
The Alumni News Letter
Contains news of the College and its alumni.