New Combined Physics Laboratory A Modern Unit Equipped For Work In All Branches Of Research

In the new Physics Research Laboratory which had its formal opening at the meeting of the American Physical Society, held in Cambridge during the last week of February, Harvard has acquired much more than a new laboratory.

The significance of the new construction is that the facilities for the study of physics at Harvard have been transformed through the generosity of a considerable number of alumni and the help of the General Education Board of the Rockefeller Foundation. Instead of merely adding a new building to its two existing laboratories, Harvard has turned the three into a single large, modern unit, well equipped for work in practically all branches of the subject, and for all grades of instruction, from elementary courses to the most advanced research.

The new building joins the Jefferson Physical Laboratory, built in 1884, to the Cruft High Tension Electrical Laboratory, completed in 1914. By locating the new construction at this point the Department has been able to revise and consolidate the electrical installations in the older buildings, to give a new value to its machine shops through centralizing them, and to devote the entire new laboratory to research.

Space Economized

By using the power rooms of the Jefferson and Cruft buildings for the installation of new generating apparatus supplemental to extensive existing equipment, space was economized, and all sources of mechanical disturbance were kept at a distance from the new research quarters. The 100,000 volt storage battery, one of the most powerful high voltage batteries in this country, has been moved to the basement of the research laboratory. Undergraduate instruction is to be carried on in the Jefferson Laboratory.

In the Cruft Laboratory, teaching and research will continue in the field of high-frequency phenomena, communication engineering, and certain parts of the subject of acoustics. The building is surmounted by two steel radio towers.

One Machine Shop for Bridgman

The Jefferson Laboratory has been altered in a number of particulars. In the east end of the building and in the central portion on the north side, concrete construction was substituted for wood. Three machine shops are now located in the building, directly accessible to the new Research Laboratory. One is devoted exclusively to the use of Professor Bridgman, for his work on high pressures; one is for general work, and one is a precision shop. The Department of Physics has acquired, through the generous gift of Mrs. Gannett, the very valuable collection of lathes and machines tools, once the property of the late Dr. W. W. Gannett, Harvard '74.

The engineers of an electric system for a building such as the new Physics Laboratory have a more diversified problem than in any other type of electrical installation. A power plant may require higher power, a telephone plant may require more wires, but the installation in a physics laboratory must be more flexible than either. The Harvard Laboratories unit is an excellent example of how the difficulties of the wiring situation has been successfully overcome.

Pioneer Experiments Since 1884

The character of the work which the building is designed to permit is probably best conveyed by a description of the work already going on there. The Harvard laboratories have since the completition of the Jefferson building in 1884 been the scene of a series of the most outstanding pioneer experiments, and in certain fields the position of the University is still unchallenged. The work of Professor Sabine, which laid the foundation for all of modern architectural acoustics, was carried on in a room in the basement of Jefferson Laboratory still used for this purpose.

Researches in general physics furnished the material for the work going forward in the Jefferson Laboratory in the past. Radiations which are the vehicle of "wireless" or "radio" communication--of greater wave-length than those of the visible spectrum--have been the especial interest of the members of the Harvard physics staff in the Cruft Laboratory.

Professor Percy W. Bridgman, whose laboratory has been moved to the new Research Building, occupies in various respects a unique position. He is acknowledged to be the leading authority in the world on the laboratory applications of high pressure and the behavior of solid and liquid materials under such pressure. He has attained the highest pressures on record in laboratory experimentation. An extremely prolific experimental investigator, he is at the same time a profound writer on the philosophical aspects of physics.

Crystal Controlled Oscillator

A laboratory so much devoted to the study of electric circuits as is the new Research Laboratory requires a highly accurate central equipment for checking frequencies. A crystal-controlled master oscillator of 50,000 cycles, with submultiple and harmonic frequency multipliers giving frequencies of 1000 cycles, and any multiple thereof up to more than 20 million cycles is part of the equipment of the building. It has an accuracy and constancy at all frequencies better than one part in five million.

Selected frequencies from this precision station are amplified and may be transmitted to all parts of the three buildings. These frequencies, when desired, may also be used as master control of the laboratory radio transmitting sets. Another unit, a 1000-cycle master oscillator is used to supply 1000-cycle current to student laboratories and researches not requiring extreme precision. This oscillator is controlled in frequency to one part in 100,000 by a thermostated magnetostriction rod.

Professor Pierce's Work

Professor George W. Pierce has been one of the pioneers in the work on quartz-oscillators and magnetostriction rods which makes possible these measurements of frequency. His work has been with mechanical and electrical oscillations and their combined effect upon electric circuits. Apparatus containing these developments is used as the basis of frequency measurements in all modern radio broadcasting applications.

For fifty years there has been knowledge of the electrical effect due to mechanical operation on quartz. In the 1890's, the Curie family worked on this problem. Here and abroad during the War, work on vibration of quartz plates by electrical means was carried on. They were used for depth finding by high frequency of sound reflected from the ocean bottom. Quartz vibrators were used for production and reception. Professor Pierce, and others, also found at this time that the quartz crystal was useful in stabilizing electrical oscillations.

Since any mechanical vibration is sharply resonant, and better than the best electric circuits which can be built Professor Pierce has also been at work on magnetostriction rods, usually an alloy of nickel and steel, used, experimentally, as a source of air waves, similar to sound waves, but above audible limit, especially in the range: 30,000 to 50,000 cycles. Such waves can be focused, confined to narrow beams like those from a searchlight. Both the quartz crystal and magnetostriction rod are being worked on for communication purposes, and are also used to study the elastic properties of materials.

Edwin H. Hall, Professor Emeritus, continues to carry on experiments on conduction in metals. In the new building he has set up new devices for studying these problems.

Spectra and Sound

Professor Frederick A. Saunders has done his main work in spectroscopy; he was a pioneer in the study of series spectra long before the importance of this subject was generally recognized. He is also an authority in the domain of sound from the theoretical, practical and aesthetic points of view. In this field he has been the successor at Harvard of Professor Sabine.

Professor Emory L. Chaffe has done his principal work in the realm of electric oscillation and electric waves, with special reference to vacuum-tube phenomena. He has also devoted himself to biophysical problems, notably to a study of the electric response of the retina when stimulated by light.

Experiments on conduction in gases are being carried on by Professor Otto Oldenberg, who came to Harvard in 1930. His special field is the excitation of atoms and molecules studied largely by spectroscopic methods. He has also organized a course of fundamental experiments in atomic physics for graduate students.

New Grating Room

Assistant Professor F. H. Crawford is engaged in a study of the light emitted by the atoms and molecules of a gas under the influence of various types of electrical discharge. He is in charge of the new grating room. In an outer room ample space is available to accomodate apparatus used in the preliminary study of spectroscopic questions. Inside the grating room, the space occupied by the twenty-one foot concave grating is seperated from the rest of the room in such a way that the temperature within it may be kept constant. A circular bench of concrete is provided, which carries the supports for the holders of the photographic plates, upon which the lines of the spectrum are reproduced for further study.

Professor Theodore Lyman is Director of the Jefferson Laboratory. His field of research is the study of light of extremely short wave length.

Part of the time of Professor William Duane is spent at the Huntington Hospital, where he devotes himself to the use of X-rays and the radiation from radioactive substances in the treatment of maligant disease; part is devoted to research in pure science in the laboratories at Cambridge. His title is that of Professor of Biophysics.

X-ray Laboratory and Vault

His work in Cambridge is carried on in a large X-ray laboratory and special vault which extends beyond the wall of the main building. These rooms have been constructed in the basement of the new Research Laboratory, and located so that the rest of the laboratory may be protected from the distrubing influence of the high voltage X-ray tubes.

Professor Edwin C. Kemble and Professor John C. Slater, now Lecturer at Harvard, as well as head of the Department of Physics at the Mass. Institute of Technology, specialize in theoretical physics. They have given much attention to the general theory of radiation, as based upon the conceptions of Planck, Bohr, Einstein and others.

On the top floor of the new building a modern radio transmission laboratory for the study of the reflection and refraction of radio waves from the Kennelly-Heaviside layer is now in course of construction. This laboratory will include all the new types of apparatus ordinarily used in such researches and in addition a new type of recording device designed to give continuous records over an extensive period of time.

FEATURES OF NEW UNIT

1. Three laboratories turned into one large, well-equipped, modern unit.

2. 100,000 volt storage battery located in the basement.

3. Three machine shops directly accessible to Research Laboratory.

4. A crystal-controlled master oscillator of 50,000 cycles, with submultiple and harmonic frequency multiplers.

5. Equipment for carrying on experiments on conduction of metals.

6. Apparatus for research in spectroscopy, sound, vacuum-tube phenomena, and electric response of the retina when stimulated by light.

7. Quarters for experiments on gases, and the excitation of atoms and molecules studied largely by spectroscopic method.

8. A 21-foot concave grating, and a special room to house it with a constant temperature for spectra study.

9. A large X-ray laboratory and vault in the basement, located so that the rest of the laboratory may be protected from the disturbing influence of the high-voltage X-ray tubes.

10. A radio transmission laboratory for the study of the reflection and refraction of radio waves from the Kennelly-Heaviside layer, now in the course of construction.