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A Simple Method Of Determining Horizontal Intensity Of The Earth's Magnetic Field, E. P. T. Tyndall

Proceedings of the Iowa Academy of Science

This method of determining the horizontal intensity of the earth's magnetic field depends on well-known principles, which, however, do not seem to have been applied in exactly this fashion before. A magnet is suspended in a horizontal plane and allowed to vibrate under the joint influence of the earth's field and a known controlling field in the same direction and in either the same or opposite sense. The controlling field is that of two similar circular coils placed a distance apart equal to the radius (arrangement of Gaugain and Helmholtz).

The Orientation Of Buildings On The Basis Of Sunlight, Wm. Kunerth

Proceedings of the Iowa Academy of Science

The value of sunlight to both animal and vegetable kingdom has always been recognized, but very often not fully appreciated. We know that it is beneficial to get much sunlight, but very few of us know just how much we are getting under any one set of conditions, nor do we know whether we are getting more of less than under another set of conditions. It was with this in mind, that it seemed desirable to ascertain the relative amounts of direct sunlight entering a vertical window when the window was facing in one direction in one case and in …

College Circular [Catalog] 1924, Iowa State Teachers College

UNI Programs and Courses Catalogs

Table of Contents

Calendar for 1924-25 ... 5
Officers of Administration and Instruction ... 6
General Information ... 39
Residence, Student Health, Assembly ... 39
Expenses and Fees ... 40
Free Scholarships ... 41
Extension Service ... 42
College Organizations ... 42
Faculty Organizations ... 46
Training in Actual Teaching ... 43
Public Lectures and Entertainments ... 43
Boarding and Lodging ... 44
Employment of Students ... 45
Twelve Weeks Normal Training ... 45
School Credits in Lieu of Certificate Examinations ... 46
Examinations for Teachers Certificates ... 47
Department Certificates ... 47
Bureau of Recommendations ... 47
Advisers and …

The Physical Properties Of Some Short Period Anneal Products Of White Cast Iron, Anson Hayes, W. J. Diederichs

Proceedings of the Iowa Academy of Science

Since very little study of the malleableizing process had been made and also because the properties that were considered of primary importance to the average user of malleable iron were ease of machining and ductility, no attention has been paid to the industrial possibilities of partially graphitized white iron. In annealing periods of less than 11 hours total duration it has been found possible to produce irons ranging from 70,000 strength and 5% stretch to 55,000 and 10% stretch depending on varying rates of cooling of 6°F. per minute to 3°F. per minute from the annealing temperature. The unusual properties …

Phenomena Of Cathode Sputtering, K. V. Manning

Proceedings of the Iowa Academy of Science

When metal is deposited cathodically upon a glass plate a film is found upon the side of the plate away from the cathode. In the study of this deposit both alternating and direct potentials were employed. An attempt to increase the deposit by various reflecting surfaces gave negative results. A possible explanation of the phenomenon is offered, based upon the assumption that the metallic particles receive a positive charge after leaving the cathode. An attempt to sputter non-conductors in the form of metallic oxides gave negative results.

Electrical Constants Of Dielectrics For Radio Frequency Currents, R. V. Guthrie Jr.

Proceedings of the Iowa Academy of Science

The electrical constants of dielectrics are the power factor and the dielectric constant, the power factor being that of a carefully insulated condenser using the given material as the dielectric. Losses in a condenser may be represented either as a series or a parallel resistance. If considered as in series, the losses may be determined by resistance variation, and if in parallel, the geometric capacity may be determined. From a consideration of both, the power factor ψ and dielectric constant K may be obtained from simple formulae. An investigation of several solid dielectrics over a band of frequencies ranging from …

Measurement Of The Acoustic Impedance Of A Branch Line, G. W. Stewart

Proceedings of the Iowa Academy of Science

Acoustic measurement is in its infancy and that of acoustic impedance is peculiarly difficult. A theory of a new method of the measurement of acoustic impedance is presented herewith. How useful it may become must be determined through experience.

1924 Old Gold, Iowa State Teachers College

UNI Yearbooks

The student yearbook of the Iowa State Teachers College, later known as the University of Northern Iowa.

Table Of Contents

Proceedings of the Iowa Academy of Science

No abstract provided.

Preliminary Report On The Optical Properties Of Magnesium, M. E. Graber

Proceedings of the Iowa Academy of Science

The present research on the optical properties of single magnesium crystals was carried forward in the laboratories of the University of Iowa under the direction of Prof. L. P. Sieg. Employing the crystelliptometer, plane polarized monochromatic light was reflected from the crystal surface and the resultant elliptically polarized light analyzed to determine the phase and azimuth angles of its components. The crystals were studied in two positions: parallel and perpendicular, respectively, to the principle axis of the crystal, and two sets of optical constants (index of refraction, absorption index and reflecting power) were determined. Within the range of wave lengths …

Adsorption From Salt Solutions By Colloidal Copper Ferrocyanide, Mikkel Frankert, J. A. Wilkinson

Proceedings of the Iowa Academy of Science

In order to compare the two views as to the cause of the acidity developed when a soil is treated with a neutral salt solution (selective adsorption and base exchange theories) colloidal copper ferrocyanide was treated with different salt solutions of varying strengths and the alkalinity or acidity developed was compared with the amount of copper dissolved. Potassium salts developed a whole series from a small amount of acidity to a large amount of alkalinity.

A Method Of Measuring Rates Of Corrosion Of Iron In The Presence Of Carbon Dioxide And Air And The Influence Of Electrical Potentials On Such Rates, Anson Hayes, E. Lee Henderson, C. E. Staneart, G. H. Brodie

Proceedings of the Iowa Academy of Science

The method consists in subjecting cylindrical samples of 4ft. by 1/10 ft. wrought iron to the action of water saturated with the gas mixture. The water and gas are passed through the cell at such a rate as to insure a constant and known composition. A precision of 5% is obtained in runs of 48 hours duration. 4% CO₂ mixed with air dissolves 1 gram of iron per square centimeter of exposed surface in 735 days while it required 1927 days with air alone. A fall of 25/100 millivolt per centimeter increased the rate of corrosion 28%. 25/1000 millivolt …

New Measurements In The Process Of Reading, E. O. Finkenbinder

Proceedings of the Iowa Academy of Science

The lectometer is a special form of tachistoscope which provides a connection with a chronoscope. Through an open, adjustable sector of a rotating disc is presented material for reading. Just as the view is shut off a small arm attached to the spindle of the disc dips into mercury, thus completing an electric circuit which sets the chronoscope into action. The observer reads into a voice key which stops the chronoscope and gives the time to the thousandth of a second it takes him to know and say what he had observed during the short view.

Note On The Theory Of The Optimum Angle Of A Conical Horn, G. W. Stewart

Proceedings of the Iowa Academy of Science

Hoersch has given a theoretical explanation of the optimum angle of a conical horn experimentally found by the writer. The optimum angle is the one giving the greatest amplification, the horn acting as a receiver. The theory of Hoersch states that the angle is an optimum when the dissipation at the vertex is equal to the dissipation at the open end.

Rainbow And Other Atmospheric Phenomena, F. May Tuttle

Proceedings of the Iowa Academy of Science

Perfectly well behaved rainbows are usually supposed to appear opposite the sun, following a shower; but they sometimes change their minds and appear elsewhere. During the past three years we have been jotting down a few notes and felt they might be of interest to other students of nature's wonderland.

Maxwell's Treatment Of Networks Applied To The Delta Connection Of A Three-Phase Power Source, Alfred W. Meyer

Proceedings of the Iowa Academy of Science

There are two purposes in this paper. The more subordinate one is to give the results of the particular problem. The more important reason for the paper is that it may suggest a means of solution of similar problems. The question arose as to the relation between the electromotive forces of line currents and the electromotive forces of the currents in the delta connected load lines of a three-phase service. There are four possible arrangements. The alternator coils may be in Y or delta connection and with either of these there may be a Y or delta connection between the …

Index

Proceedings of the Iowa Academy of Science

No abstract provided.

Officers, Past Presidents, And Members, Iowa Academy Of Science

Proceedings of the Iowa Academy of Science

No abstract provided.

Magnetic Properties Of Evaporated Iron Films, A. Sorenson

Proceedings of the Iowa Academy of Science

A study was made of the magnetic properties of iron films deposited on tin foil in a high vacuum by the evaporation method used by J. C. Steinberg. The magnetization curves and hysteresis loops were obtained by an induction method in which the specimen, inserted in a search coil, was placed in a magnetic field of known strength and then suddenly removed from the search coil. The resulting flux was measured by means of a galvanometer which, in order to obtain the required sensitiveness, was kept on open circuit all the time except for an instant while the current passed …

Contributions To Knowledge By Gustavus Detlef Hinrichs, M.D., Ll.D. (Paper Presented At The Thirty-Eighth Annual Meeting Of The Iowa Academy Of Science), Charles Keyes

Proceedings of the Iowa Academy of Science

As an original organizer and charter member of the Iowa Academy of Sciences, that society which is the parent of our present Academy, the latter holds with peculiar attachment the memory of the late Dr. Gustavus Hinrichs, who is, for more than a quarter of a century, also identified with the faculty of our State University as one of its most distinguished members. He further organizes and conducts for 15 years our State Weather Service, the first of the kind to be inaugurated in this country. A brief life-sketch of this gifted man appears in our Proceedings of last year, …

A Suggested Classification For Bacteriological Media, Henry W. Schoenlein Jr.

Proceedings of the Iowa Academy of Science

The compilation of the formulae and methods of preparation of the media and substrata described in the literature for the support of growth of microorganisms is a task that has seemed of sufficient practical importance to warrant its being undertaken by the bacteriological laboratories of the college. In order that these data, with reference to each medium, and an elaborate system of cross indices might be prepared, it was necessary to have some definite scheme of classification. A review of the literature shows that several types of classification for media have been suggested by different authors.

The Prairie Of The Mississippi River Bluffs, B. Shimek

Proceedings of the Iowa Academy of Science

The rugged bluffs along the upper Mississippi river, particularly those which border that part of the river flowing between Iowa and Wisconsin, display irregular treeless tracts on their slopes which are sure to attract the attention of observers who travel along the river either by water or by land.

A Method For The Production Of Longitudinal Sound Vibrations In A Rod, William D. Crozier

Proceedings of the Iowa Academy of Science

In connection with some work being done in the testing of acoustic wave filters in solid media, a method has been developed for the production of longitudinal sound vibrations in a rod. Electrical oscillations are generated in a vacuum tube oscillator, pass through two stages of power amplification, and are used as the input to a special oscillator attached to the end of the rod. This oscillator is similar in principle and construction to the Fessenden oscillator used in submarine sound signaling. Vibrations which have a fair purity of tone, and which have a considerable intensity over a wide range …

The Optical Constants Of Crystals Of Selenium Tellurium For Wave-Lengths From 3000 To 5000 A, R. F. Miller

Proceedings of the Iowa Academy of Science

The measurements were made by a photographic method, for two positions of the crystal (1) with the optic axis parallel, and (2) with the axis perpendicular, to the plane of incidence. Two sets of optical constants were found for each substance. For selenium, in the parallel position the index of refraction was found to vary from 3.4 to 4.4, and the reflecting power from 0.38 to 0.46; in the perpendicular position the index varies from 2.3 to 3.1, and the reflecting power from 0.41 to 0.34. For tellurium, in the parallel position the index varies from 1.9 to 2.9, and …

The Hall Effect And Specific Resistance In Evaporated Films Of Nickel, Cobalt, Palladium And Platinum, H. B. Peacock

Proceedings of the Iowa Academy of Science

Steinberg has shown that in the case of a thin film of metal formed by evaporation from a heated filament in a high vacuum the specific resistance and Hall coefficient are not the same as for the bulk metal. The metals investigated were silver, copper and iron, and in all of these the specific resistance was found to be about 1000% greater than in the metals in bulk. The Hall coefficients were slightly smaller for silver and copper than for the bulk metals, but for iron this coefficient was about 600% greater than the value generally accepted for iron. Also, …

The Intrinsic Intensity And Percent Of Polarization Of Light Transmitted Through Deep Slits, L. P. Sieg

Proceedings of the Iowa Academy of Science

It is assumed that the light incident upon the first opening of a slit between various metals is diffracted in the usual manner, and finally emerges from the far end of the slit after repeated reflections. The reflecting coefficients of the various metals considered are calculated for the proper angles of incidence from a knowledge of the index of refraction of the metal, and from its coefficient of absorption. In view of the fact that the coefficients of reflections for light possessing an electric vector perpendicular are much larger than for light with the electric vector parallel to the plane …

The Effect Of The Material Composing The Sides Of Deep Slits On The Intrinsic Intensity Of Light Transmitted Through The Slits, Clarence R. Smith

Proceedings of the Iowa Academy of Science

It is shown that differences in intensity of the light transmitted by a narrow, deep slit are produced by changing the material of the sides though other conditions are kept constant. With a pair of optically plane surfaces of each of the metals, steel, nickel, gold, silver and copper, a slit was prepared which could be varied in width while the depth remained constant. For each of these metals a curve was prepared showing the variation of transmitted light intensity with change in width of slit. Comparison of the curves for the various metals shows a fairly close agreement for …

The Action Of A Helmolts Resonator In A Branch Line, G. W. Stewart

Proceedings of the Iowa Academy of Science

The general impression of a Helmholtz resonator is that, since its dissipation is small, its tuning is fairly sharp. It is noted with some surprise, therefore, that when used as a side branch in an acoustic transmission line it affects the transmission over a wide range of frequencies. The theory, derived from the general case in the preceding abstract has been checked by experiment with resonators of varying dimensions and the theory verified to a very satisfactory degree.

Theory Of Megaphones And Receiving Horns, G. W. Stewart, G. R. Butz

Proceedings of the Iowa Academy of Science

In 1919, A. G. Webster published a theory of the action of horns used as receivers. Recent development has given an increased interest in the megaphone. Webster's theory may be modified to cover the case of the megaphone, assuming the constancy of the acoustic point impedance of the horn at the source. The result obtained is that the emitted energies at different frequencies are related as are the values of [(ad-bc)/(a-cz₂)]² wherein a, b, c and d, have the values specified in Webster's theory and z2=δa²k² (ki/2π-1/c₀), k being 2π …

The M Absorption Limits Of The Tungsten X-Ray Spectrum, R. V. Zumstein

Proceedings of the Iowa Academy of Science

The x-ray spectrum of tungsten has been investigated from 7 to 3 Angstrom Units, using a metal x-ray tube and a vacuum spectrometer.