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B&W Associates of Michigan City, Indiana manufactured the B&W Lie Detector shown here, during the early 1950's. This model is identical to the instrument currently used by Cleve Baxter in his ongoing experiments to determine if plants emit Galvanic Skin Response (G.S.R.) activity. The only function of the Model 8AC is to measure G.S.R. activity. The recording of G.S.R. activity had not been integrated into these early polygraph instruments, thus the G.S.R. sensitivity dial on the left side of the instrument was manually controlled by the examiner to set sensitivity at a perceived norm. The centering dial on the right side of the instrument was used to bring the G.S.R. on the instrument into calibration. The meter counts units of G.S.R, and was a very sensitive for its time. The Model 8AC also uses a automatic/manual switch which may be used if the examiner chooses to adjust the sensitivity manually prior to the first relevant question. The examiner had the option of using the automatic setting early in the test.

When in operation, a "Deception Indicated" (DI) reading is established when the pen moves above the 'CENTER' operational area on the meter. The 8AC utilizes only two fingerplates, and it is this theory that started the debate between measuring G.S.R. activity, verses the first studies in voice stress analysis.

The B&W Lie Detector shown here was used until just recently, and is still considered a reliable instrument for determining deception.



The Model 6308 shown here was manufactured by 'Keeler Polygraph' which was a division of 'Associated Research' of Chicago, Illinois. This instrument was used in the late 1960's, initially in the Military, and continued being used until the late 1970's in some States. The Model 6308 is one of the first instruments that can easily be changed from a desk mount to a portable unit without tools. The instruments three separate channels provide continuous recording of changes in heart rate and blood pressure, breathing rate and skin resistance. The G.S.R. component consisted of a pair of finger electrodes, or a hand electrode connected to a input circuit of a direct couple solid-state amplifier with a balanced differential output, feeding the pens.

The 6308 utilized a newly designed epoxy encapsulated printed circuits that assured long, trouble-free operation, and like the Model 6318, operated on four nickel cadmium batteries which were automatically recharged when the instrument was plugged into AC current. The Model 6308 is 18" x 9" x 6" and weighs approximately twenty pounds with its accessories.

The Model 6308 was sold for $1325.00, which included all required detachable accessories and initial operating supplies consisting of chart paper, ink and conducting jelly.



The Keeler Polygraph Model 6317 shown here was manufactured by the 'Associated Research Company' of Chicago, Illinois. This unit was developed and placed into service during the later part of 1939, at a time when the most common use for the polygraph was in the field of business for employment screening. During the Korean War, this instrument was utilized by the C.I.A, and again in the early 1960' to polygraph Cubian Nationals to determine if they were spies. This instrument was designed to simulate a piece of luggage, not only to meet F.A.A. regulations but to prevent it from being easily detected throughout the espionage community.

The 'Keeler Polygraph' Model 6317 weighed twenty pounds and was powered by four ordinary flashlight batteries. The manufacture provided an option of an AC power source at an additional charge, as shown with this instrument. This instrument utilized a community three pen cup inking system, which drew the ink from a small well located behind the pen positions. The G.S.R. component consists of a black plastic hand electrode assembly with two individual contact points. When the examinee placed the metal spring assembly over his knuckles, the circuit was complete with a slight squeeze of the hand. The single large pneumograph contained a brass bellow, which was placed over the examinees chest, while the cardio cuff was placed on the appropriate arm.

The Model 6317 was one of the first instruments in production utilizing a completely transistorized circuitry. It also boasted itself as being one of the first fully portable polygraph instruments. The Model 6317, along with its sister models developed by 'Associated Research' were in service until the early 1960's. This instrument sold for approximately $1450.00

The 6308 utilized a newly designed epoxy encapsulated printed circuits that assured long, trouble-free operation, and like the Model 6318, operated on four nickel cadmium batteries which were automatically recharged when the instrument was plugged into AC current. The Model 6308 is 18" x 9" x 6" and weighs approximately twenty pounds with its accessories.

The Model 6308 was sold for $1325.00, which included all required detachable accessories and initial operating supplies consisting of chart paper, ink and conducting jelly.



The 'Keeler Polygraph' Model 6338 shown here was the first 'Plethysmic Polygraph' manufactured by 'Associated Research' of Chicago, Illinois in the early 1950's. This instrument is the first in the 'Pacesetter Series' which incorporated for the first time a integral photo/optical plethysmograph. The Model 6338 was introduced as a four channel instrument, which recorded simultaneously changes in relative blood pressure, heart rate, pulse wave amplitude, blood volume, oxygenation of the blood, respiration and electrical skin resistance. These reading are obtained by utilizing electronic and pneumatic monitoring.

The 6338 required a 115 volt AC current. It weighs twenty-four pounds and is 18" x 11" x 6". The 6338 incorporated newly designed printed circuits, and a new inking system where the pens are fed from removable, individually capped ink bottles with colored ink available. The newly designed vent valves have a positive lock to prevent leaks.

The kymograph is typical of previous top loading models, but the construction allows the instrument to be mounted in a desk top. The new shockproof suspension system protects the instrument as it is suspended between two layers of foam rubber. The design of the cardio cuff, pump bulb assembly and clamp remained basically the same in the 'Pacesetter Series'. There were three different traveling cases available, which conformed to Federal Aviation requirements at the time for travel. The price for this model was $2325.00. The 'Keeler Polygraph' Model 6338 remained in service through the early 1960's.



The 'Keeler Polygraph' Model 302 shown here is one of Keeler' earlier instruments, dating back to 1953. This instrument was manufactured by 'Associated Research' of Chicago, Illinois and utilizes seven batteries, along with an AC power source. It is housed in a steel case with wrinkle finish and chromium trim. The cover is attached to the case with slip hinges allowing the cover to be removed.

The chart drive unit is powered by a synchronous motor at speeds of either six or twelve inches per minute. There are four recording pens, the lower pen and its associated controls comprise the pulse-blood pressure unit, while the longer pen records electrodermal variations. Located above the electrodermal pen is the pen for recording respiration changes, and at the top of the panel is the stimulus marker pen actuated by means of a flexible cable attached at the lower left of the panel. At the center of the panel is a standard sphygmomanometer, used as a guide to proper inflation of the blood pressure cuff.



The Lafayette Model 76056 displayed here was first introduced by Lafayette Instrument Company of Lafayette, Indiana in 1972. The 76056 was considered to be the most popular instrument introduced at the time, with double pneumographs, G.S.R., Electro-Cardio, and a top-mounted pnuematic stimulus marker. The mechanical pneumos featured stainless steel shafts with a sapphire olive ring, and bombe jewel bearings for increased sensitivity. The solid state G.S.R. on the Model 76056 is linear from 1 to 1,000,000 ohms in automatic or manual mode. The newly designed pens had a increased sweep of 5.75 inches. The newly designed electro-cardio provided quality records at low cuff pressure. This instrument also incorporated a precision friction paper drive, pen lifter bar and paper well which permitted easy chart replacement.

Lafayette Instrument Company boasted that their Model 76056 was very modular, which allowed for easy field replacement components. This polygraph instrument was lightweight, and enclosed in a sturdy Haliburton case, which also had in the case accessory storage.

The Model 76056 was priced at $2148.00 dollars, and was available with an optional carrying case for $28.00 dollars. This instrument was used in Texas until early in 1981.



The 'Berkeley Psychograph', or other wise known as the 'Lee Polygraph' shown here was first introduced in Chicago, Illinois in 1938. This instrument is the improved model, which was developed by Captain LEE of the Berkeley California Police Department.

This instrument was designed to be a compact, portable unit which encompasses a novel arrangement of rubber 'tambours' and a manually operated stimulus key. Visible are the pens for recording respiration, blood pressure, pulse and stimulus response changes. The instrument includes a pressure cuff and hand bulb, along with a pneumograph tube for recording respiration change. The major difference with the Berkeley Psychograph in comparison to the earlier Keeler instruments was that the Berkeley Psychograph incorporated a new design in the pulse-blood pressure unit. Captain LEE was also the first to introduce the use of the guilt complex control question, and the first 'Control Test', which was later re-named the Pre-Test.

This type instrument was used primarily on juveniles during the 1930's, as the conventional rules of evidence did not apply at this time. The 'Lee Polygraph' was taken out of service around 1938, after Dr. BRIL, a criminologist from New York City developed his own instrument, a "Brilograph', which measured changes in skin resistance, ie: G.S.R.



In about 1955, the Stoelting Company of Chicago, Illinois which has been producing polygraph instruments since 1935, introduced the Deceptograph model 22500. This model contained vacuum tubes in its amplifier which required approximately thirty minutes of warm up time before use. It contained three recording channels, cardio, pnuemo and G.S.R., which provided a continuous recording of changes in relative blood pressure, heart rate, pulse wave amplitude, respiration and electrical skin resistance. The A.C. component unit was packaged in an aluminum Halliburton case with sectionalized components and a built-in microphone cartridge. The 22500 also had an individual inking system which consisted of a pen tip, fork, counter balance, plastic tubing, ink reservoir and ink reservoir receptacle. The 22500 weighs approximately thirty-one pounds with its accessories, and its dimensions are 18" x 9" x 6". The 22500 uses the standard 110 volt, 60C alternating current.

The 22500 model displayed here was advertised as the most widely used polygraph instrument in the world, and was primarily used in the United States Military.



The Model 22600 Polygraph instrument was introduced by the Stoelting Company of Chicago, Illinois in 1966. This instrument replaced the 22500 model with the most significant change being the replacement of old vacuum tubes with transistors which reduced the weight and size of the instrument along with eliminating the previous warm up time.

This model is a three pen instrument. The top channel was a mechanical recording channel for recording respiration. The instrument did not have any means of controlling tracing size, except for possibly adjusting the pneumograph tube. The G.S.R. channel was a 250,000 ohm amplifier, balancing a twenty three micro amp current to the subject to record changes in galvanic skin response. The bottom channel was used to record heart rate and changes in relative blood pressure. Due to the mechanical nature of the recording, optimum tracings were not always obtainable.

The 22600 was the last instrument produced by Stoelting which utilized the single pneumograph, and the six inch chart paper. A few years after the 22600 was introduced, Stoelting produced its first four pen polygraph, which incorporated a second pneumograph and a kymograph which recorded on eight inch paper.



This polygraph instrument is one of the first production instruments produced by the Stoelting Company in Chicago, Illinois. This instrument was originally designed by Cleve Baxter, who presented his plans to the Stoelting Company, who made some minor design variations before it went into production in the early 1950's.

This instrument operated on a standard 115 volt current sixty cycle current, and did not have alternate battery capacity. It was considered to be very sensitive for its time, but only operated on a two pen inking system, recording pneumo and cardio tracings. The blood pressure gauge manufactured by Stoelting recorded pressure from zero to three hundred. The two pens recorded on six inch paper. The single Pneumograph was attached to the examinee by placing the small chrome cup directly over the subjects heart.

During the late 1950's, a polygraph examiner named R. Chattum used an instrument identical to this one in employee screening at the Atomic Energy Commission in Oakville, Tennessee.

The instrument displayed here was first used by the Abilene Police Department in 1955, and later used by one of the local Sheriff's department until 1970. This instrument was retired in September of 1981.



Special thanks to the Texas Department of Public Safety Polygraph Examiners Class of 1999 for the research, organization and presentation of the information contained on this page and it's links. The historic background information was obtained from numerous journals including manuals from Stoelting, Lafayette and Keeler Instrument Company. Additional information was obtained from several other investigators and a telephone interview with Cleve Baxter.