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A Comparison Of Intensities Required Under Direct And Under Indirect Lighting Systems, Wm. Kunerth

Proceedings of the Iowa Academy of Science

Although artificial indirect lighting dates back twenty-five years or more, it was not very extensively patronized until after 1906 when the advent of the more efficient Mazda B lamp made its commercial use possible. At once comparisons were made between the direct and the indirect systems on various points.

A Chemical Classification Of The Activities Of Soil Microorganisms, Paul Emerson

Proceedings of the Iowa Academy of Science

At the present time it may be said that the process of decomposition with its resultant complex chemical changes taking place in the soil is controlled primarily by the activities of micro-organisms and that Soil Fertility is mainly dependent upon these microscopic forms.

The Alumni News Letter, V5n4, October 1, 1921, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

The Alumni News Letter, V5n3, July 1, 1921, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

Spring Term Commencement [Program], May 31, 1921, 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, V5n2, April 1, 1921, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

Winter Term Commencement [Program], March 8, 1921, 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.

Methods Of Teaching Parasitology, Herbert R. Werner

Proceedings of the Iowa Academy of Science

The fact that animal parasites are important as disease producing agents has been known for a great many years. Thought, consideration, study, and emphasis on the question of parasitism have come in waves; at times it was looked upon as one of the most important factors to be dealt with, while at other times or periods it has received almost no attention and parasites have been looked upon as more or less unimportant as disease producing agents. But the necessity for the protection of our livestock from disease has grown, being governed largely by the supply and demand, together with …

1921 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.

The Alumni News Letter, V5n1, January 1, 1921, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

Hall Effect In Thin Silver Films, J. C. Steinberg

Proceedings of the Iowa Academy of Science

The Hall Effect as a function of thickness has been investigated in chemically deposited films of silver, of thickness ranging from 40 to 200 millimicrons, and the Hall Coefficient found to be independent of both magnetic field, for fields up to 20000 Gauss, and thickness. The specific resistance of the same films increases as much as 200 per cent for some of the thinner films. These results are in good agreement with those obtained by Dr. G. R. Wait last year.

Table Of Contents

Proceedings of the Iowa Academy of Science

No abstract provided.

The Coefficient Of Simple Rigidity And Young's Modulus For Hexagonal Crystals Of Selenium, L. P. Sieg, R. F. Miller

Proceedings of the Iowa Academy of Science

Elastic constants determined from drawn wires are of considerable practical use, but they are not very illuminating on the subject of the structure of matter. A drawn wire is a heterogeneous mass of matter in crystalline and amorphous states, with never any regularity in composition or of crystalline structure. In fact the elastic constants so determined are not so much characteristic of the substance, say copper, as of the particular physical state of that substance. If, however, one could employ an isolated crystal of a simple elementary substance, he ought to be able to determine the elastic constants of the …

Some Pleistocene Exposures In Des Moines, James H. Lees

Proceedings of the Iowa Academy of Science

In the early spring of 1921 as the writer was examining the face of the bluff bounding the north side of the Des Moines valley just below the Capitol grounds he noticed, on the west side of the entrance to a ravine between Southeast 13th and 14th streets, where the State operated a small drift coal mine for some time, a section of Pleistocene material above the Coal Measures sandstone, which seemed to present features of some interest. Closer inspection showed the probable presence of two drift sheets and since the superposed evidence of successive invasions of the continental glaciers …

College Catalog And Circular 1921, Iowa State Teachers College

UNI Programs and Courses Catalogs

Table of Contents

Calendar for 1921-1922 ... 5
Officers of Administration and Instruction ... 6
General Information ... 32
Residence, Student Health, Assembly ... 35
Expenses and Fees ... 36
Free Scholarships ... 38
Extension Service ... 38
College Organizations ... 39
Faculty Organizations ... 39
Training in Actual Teaching ... 40
Public Lectures and Entertainments ... 40
Boarding and Lodging ... 40
Employment of Students ... 42
Twelve Weeks Normal Training ... 42
School Credits in Lieu of Certificate Examinations ... 42
Examinations for Teachers Certificates ... 42
Department Certificates ... 42
Bureau of Recommendations ... 42
Degree Curriculums …

Measurements Of The Amplitude Of Vibration Of The Diaphragm Of The Hewlett Tone Generator, C. E. Lane

Proceedings of the Iowa Academy of Science

The "New Tone Generator" designed by Dr. C. W. Hewlett promises to be a very valuable instrument for use as a precision source of sound. The operation of the instrument has been investigated mathematically by its designer and a method is given for calculating the amplitude of vibration of its diaphragm from the electrical input. The writer herein describes a method whereby it has been possible to make actual measurements of the amplitude by mechanical means for comparison with the calculated amplitudes. The tone generator was used in a vacuum tube oscillatory circuit from which the desired frequencies of alternating …

Corn Oil Cake Meal For Growing And Fattening Pigs, John M. Evvard, Russell Dunn

Proceedings of the Iowa Academy of Science

Corn oil cake meal is really a residue of the germs of corn grain which remains after most of the oil is extracted therefrom. The particular corn oil cake meal which we used in our test is a by-product from the manufacture of glucose. These four main products are made from the corn grain: Glucose, corn oil, gluten feed, and corn oil cake meal. It is with the latter that we are to deal.

In Memoriam: E. W. Stanton, L. H. Pammel

Proceedings of the Iowa Academy of Science

No abstract provided.

A Laboratory Optical Pyrometer: Notes On Its Design And Operation, Wm. Schriever

Proceedings of the Iowa Academy of Science

The writer was confronted with the problem of measuring the temperature of a tungsten wire enclosed in an evacuated tube. A thermocouple could not be used because it would be certain to apply unknown torques to the wire and also to disturb the temperature distribution along the wire. An optical or radiation method of temperature measurement would overcome both of these difficulties. An optical pyrometer suitable for accurate temperature determinations and flexible enough to be of general use in a physical laboratory is not on the market at the present time. This led the writer to the task of designing …

Measurements Of The Minimum Audible Intensity Of Sound For Tones Of High Frequency, C. E. Lane

Proceedings of the Iowa Academy of Science

Many investigators have worked on the problem of determining the minimum amount of sound energy necessary for audible perception, but most of the investigations have been concerned with sounds of ordinary frequency and very little attempt has been made to make such a determination in absolute units near the upper limit of the range of audition. The mechanical difficulty of securing tones of sufficient intensity at these high frequencies is great, and, furthermore, it is not so easy to ascertain the amount of sound energy given out from the sounding apparatus at these values of frequency as at lower values.

The Tactual Analog Of Stroboscopy, L. E. Dodd

Proceedings of the Iowa Academy of Science

The subject of coincidences has application in stroboscopy, or the stroboscopic effect, in vision, and in the phenomenon of musical beats in audition. By means of a suitable mechanical device it applies also to the tactual sense. There may thus be produced tactual, as well as musical and optical beats.

The Blackening Of A Photographic Plate As A Function Of Intensity Of Monochromatic Light And Time Of Exposure, P. S. Helmick

Proceedings of the Iowa Academy of Science

By an empirical modification of Hurter and Driffield's and Ross formulae, it has been possible to express the blackening of a photographic plate exposed to monochromatic light as a function of intensity of light and time of exposure with an accuracy within the limits of the experimental data at hand. By means of monographic charts the constants of the equations can be computed by semi-graphical methods.

Alcohols As Factors Altering Fatigue Processes In Frog Muscle, Francis Marsh Baldwin

Proceedings of the Iowa Academy of Science

In a recent paper experiments were cited which indicate that developing sea-urchin eggs when subjected to suitable concentrations of various liquid-soluble substances, i.e., the higher alcohols, show unmistakable rhythms of susceptibility and resistance according to the phase of physiological activity at the specific time of treatment. Such observations constitute additional evidence that a very intimate relation or correlation exists between the general physiological condition of the egg, and the physical state of its plasma-membrane. The present paper is a preliminary report of experiments conducted in the light of recent advances to analyze the effects of various concentrations of the alcohols …

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

Proceedings of the Iowa Academy of Science

No abstract provided.

A Single Band Acoustic Wave Filter, G. W. Stewart

Proceedings of the Iowa Academy of Science

Theoretical considerations lead to the conclusion that a single band acoustic wave filter can be made in a manner analogous to the electric wave filter and also that in the acoustic case there should be a repetition of the band at high frequencies. The accompanying drawing shows the results of experiments with two filters whose dimensions also are indicated.

The Alpha Lines In The "K" Series Tungsten Spectrum, Charles Crofutt

Proceedings of the Iowa Academy of Science

According to Bohr's theory of the atom, radiation takes place only when an electron goes from one orbit to an orbit closer the nucleus. If W represents the energy associated with an orbit, that is, the energy required to remove an electron from the orbit to infinity, the energy radiated when an electron goes from orbit (1) to orbit (2) will be W₂ - W₁ = h, where orbit (2) is closer the nucleus. Assuming that an absorption frequency corresponds to the energy associated with a ring of the Bohr atom, the difference between two absorption frequencies should …

The Alumni News Letter, V4n4, October 1, 1920, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

Summer Term Commencement [Program], August 19, 1920, 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, V4n3, July 1, 1920, Iowa State Teachers College

The Alumni News Letter

Contains news of the College and its alumni.

Spring Term Commencement [Program], June 1, 1920, 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.