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Display consoles of the Whirlwind I computer, partof the S A G E North American continental defense system.
professor of electrical engineering at M.I.T.; Jerome Freedman, Dr. S. N. VanVoorhis; and Dr. J. W. Forrester.
A Joint Services Advisory Committee with representation from each service meets regularly with the Lincoln management. The current members of this committee are : Lt. Gen. D. L. Putt, USAF, chairman; Col. J. K. Johnson, USAF, recorder; Brig. Gen. J. P. Daley, USA; Brig. Gen. F. F. Uhrhane, USA; Rear Adm. R. Bennett, II, USN; and Capt. Ε. H. Eckelman, Jr., USN.
In addition to specific projects such as SAGE, one of the significant areas of work at Lincoln is radar research and development for land, sea, and airborne uses. Studies are being made to improve the transmitting, receiving, and display components. Increasing useful range and improving operation under unfavorable weather conditions are other radar research objectives.
Development of the ionospheric and tropospheric scatter systems of long-range radio communications, following fundamental work in physics and engineering, is another Lincoln project. These systems provide ultra-high frequency beyond-the-horizon radio communication of extremely high reliability.
A general listing of specific kinds of research and development at Lincoln would include digital data transmission, solid-state physics including both transistors and magnetic ferrites for digital computer and radar applications, improved ground and airborne radars, long-range radio communications, anti-aircraft weapons systems, theory of sample data servo systems, psychological research on training and operator relationships to equipment and systems analysis, simulation, and evaluation.
Facilities at Lincoln and its affiliated M.I.T. Barta Building in Cambridge include a semiconductor physics laboratory, physical chemistry laboratory, metallurgical and ferrite laboratories, low temperature research facilities, a mechanical engineering group specializing in structures, electromechanical design and heat transfer, vacuum tube construction shop used for special cathode-ray display tubes, microwave research facilities, three large-scale digital computers, extensive shops, drafting rooms, and a photographic laboratory.
Further facilities located in various parts of New England and the United States include more than 20 field stations for testing and development work, an experimental radar and communications network under M.I.T. operational control covering eastern Massachusetts for air defense tests, and experimental test aircraft support from the Air Force and Navy.
Air Force Cambridge Research Center
The Air Force Cambridge Research Center (AFCRC) is one of 10 special centers assigned to the Air Research and Development Command to carry out its mission of attaining and maintaining qualitative superiority in equipment for the U. S. Air Force. The Center is under the command of Maj. Gen. R. C. Maude.
For the past two years, AFCRC has gradually centralized its activities at Laurence G. Hanscom Field, Bedford, Mass. Although several highly specialized laboratories will be retained in other areas, the main research efforts of the Center will be conducted in modern buildings located less
than half a mile from the Lincoln Laboratory.
The mission of the Center is twofold: First, through its three major directorates, it accomplishes research, development, and test in the fields of electronics, geophysics and human factors. The three components— Electronics Research Directorate, Geophysics Research Directorate, and Operational Applications Laboratory—carry out their missions within their own laboratories, or through work done on contract by universities, research foundations, and industry. Second, the Center provides for administration and support of the Lincoln Laboratory, operated under contract by the Massachusetts Institute of Technology.
THE SCHOOL OF DENTISTRY, Loyola University, Chicago, 111., 2V2 years ago pioneered in the use of closed-circuit television to help teach dental students.
At present, according to Dr. A. R. Baralt, Jr., dean of the Dental School, television is used to teach more than a dozen courses and the results have far exceeded early expectations.
The program was devised by Dr. Baralt and J. E. Blickenstaff, the school's visual aids director.
Every floor and every classroom is now wired for closed-circuit television reception, with programs originating in either surgery or the school's television studio. Two clinical floors of the building, three laboratories, a post-graduate room and two amphitheatres also are connected to the closed-circuit system to facilitate transmission of visual and audio impressions throughout the school.
An example of television's tremendous value to dental instruction is pointed out by Mr. Blickenstaff, when referring to its use in conjunction with a once-a-week sophomore lecture-demonstration course in operative dentistry which is conducted by Dr. F. M. Amaturo, faculty secretary and associate
The bulk of the Center's support to Lincoln (including materiel, flight test, and the manning of an experimental air defense network) is provided by the 6520th Test Group (Support). Using the flight facilities at expanding Hanscom Field, planes of many types assigned to the 6520th Test Group (Support) fly missions in support of the Lincoln Laboratory. With the Lincoln Laboratory, the Raytheon Laboratory, the buildings of the Commonwealth of Massachusetts, the recently added 49th Fighter Interceptor Squadron of the Air Defense Command, the 2234th Air Reserve Training Center, and several other smaller components, Hanscom Field is now a vital defense installation.
professor of operative dentistry at Loyola. Because of the inherent smallness of ma
terials under discussion, the television camera is used to project close-up images on large-screen receivers placed in the lecture hall.
Adjacent to the hall is the school's television studio, equipped with a Dage Model 101 television camera, lights, a monitor, and the other necessary equipment. A three-lens turret on the camera facilitates flexible handling of different subjects.
From this studio, Dr. Amaturo conducts his lecture-demonstration, seated at a small table on which he places large models of teeth and whole "plates" to help in his description of operative techniques. By watching a nearby monitor, he can see exactly what the students in the amphitheatre see, and adjust his actions accordingly.
The television camera is operated by Mr. Blickenstaff, who also handles lighting and controls audio conditions.
Dr. Baralt said he is particularly pleased by the way closed-circuit has reduced the time teachers formerly needed for lecture-demonstrations. In the past, he pointed out, groups of only five or six students would cluster around a table or "patient" to see,
Loyola School of Dentistry Successfully Teaches via Television
M A R C H 1 9 5 6 Of Current Interest 307
first-hand, the methods being described by the lecturer.
This meant that the instructor would have to repeat the demonstration as many as 20 times, to accommodate all students.
Now through the medium of closed-circuit television, an entire class of 100 students can watch the demonstration at the same time, thereby saving as much as three weeks time for one instructor.
Dr. Baralt explained that there are other advantages in addition to time saved. Standardization of technique is much more easily accomplished, since he needs to do an operation only once, rather than many times. Also, the enthusiasm which all teachers bring to their lecture-demonstrations is not diminished or dissipated by successive repeats of the same material.
He pointed out that because of television, teachers found they were paying more attention to visual systemization, which put greater order and clarity into their demonstrations.
A MAJOR ACHIEVEMENT that opens new possibilities in electronics was reported recently by Bell Telephone Laboratories. This is a major breakthrough in transistor technology—new fabricating techniques for an entirely new kind of transistor.
The new device's performance at very high frequencies surpasses that of any other transistor. Development is under way preliminary to manufacture.
Key to the new fabricating techniques is the development of controls over microscopic chemical layers. The heart of the new transistor is a layer 50 millionths of an inch thick.
The new techniques involve the adaptation
Mr. BlickenstafT feels students' attitudes are very favorable toward the televised lecture-demonstrations. They receive better instruction than previously was possible and in less total time, he said.
In addition to being used to teach Operative Dentistry, closed-circuit television is also used at Loyola's School of Dentistry in the following courses : Dental Materials ; Anatomy; Physiology; Orthodontia; Oral Surgery; Prosthetics; Crown and Bridge; and in numerous clinical and laboratory demonstrations.
Mr. BlickenstafT says that the television equipment has more than paid for itself. He said that $3,500 was spent originally for equipment, and that approximately $2,000 more was invested in additional equipment over the months.
"But this investment has been insignificant," Mr. BlickenstafT said, "compared to the many audio-visual advantages we have gained from our closed-circuit television system."
of the chemical process of "diffusion" used in treating silicon for the Bell Solar Battery. Diffusion is a process by which minute amounts of impurities are introduced in controlled amounts into a material.
The transistor consists of a three-layer chemical "sandwich." The center layer is known as the "base." The other two are the emitter and collector layers. The narrower the base layer can be made the higher the frequency at which it will operate. Diffusion provides a high degree of control of such microscopic dimensions.
Because of its very high frequency characteristics the new transistor appears to be ideally suited for application in guided
missiles and electronic "brains" for military and computer uses.
The new transistor could amplify 2,500 telephone conversations simultaneously on a telephone line. This is three times as many as could be handled by the best previous transistor. It is also expected to be extremely useful in television transmission, which requires a much wider communication channel than a telephone conversation.
Color television sets offer a possibility for the new transistor, too. Although vacuum tubes are now doing this job, the new transistor is much smaller, requires less power, and does not heat up like a tube. It is expected to have a longer life than a vacuum tube. The new device has been made of both germanium and silicon, with striking improvements in both.
C. A. Lee, of Bell Laboratories, is chiefly responsible for perfecting the techniques with germanium. C. S. Fuller and M. Tanenbaum have applied the diffusion technique in making the new transistor from silicon. William Shockley and G. C. Dacey were instrumental in directing work that led to this development.
Transistor performance has been measured in two principal ways. One criterion has been the number of oscillations or self-generated electrical pulses per second. A second criterion, considered by Bell scientists to be more significant, is the number of voice or communication channels that can be amplified. In this latter category, they report that the new transistor is unequaled.
Experimental units of the device made at Bell's Murray Hill, N. J., laboratories have amplified by 100 to 1 currents across a 20-mc-wide band. Either the amplification or the number of communication channels can be made three times that of any other transistor. The number of communication channels or pathways varies with the degree of amplification. For example, if the frequency band were cut in half, thus halving the number of channels, there would be twice as much power amplification.
Currently available transistors have a frequency cutoff of 1-10 megacycles, and several recently announced transistors have had a frequency cut off between 100 and 200 megacycles. Thus far, the new transistors have been found to reach a cutoff between 500 and 600 megacycles. Even though the effective operation of many military elec-
LABORATORY MODELS of new silicon and germanium transistors announced by Bell Telephone Laboratories Shown in comparison with U. S. dime. Silicon transistor, with brass cap, is at left and germanium transistor, with glass cap is at right. Models give only impression of what final transistors will look like; smaller units will eventually be manufactured. Performance of the new transistor at very high frequencies surpasses that of other transistors.
Transistor Developed with Unsurpassed High Frequency Performance
308 Of Current Interest E L E C T R I C A L E N G I N E E R I N G
OPERATIVE DENTISTRY lecture-demonstration by Dr. Frank M. Amaturo (left, seated) on closed-circuit television which is being used by Loyola University's School of Dentistry, help teach many subjects.
TV CLOSE-UPS (above) seen on two large-screen monitors gives entire class of 94 students intimate view of teacher's operative technique.