Arthur William “Bill” Haydon
Born April 25, 1906
Published in 1972
Since his youth, Arthur William (“Bill”) Haydon has been an individual whose curiosity has expressed itself in many diverse ways. It has not been an idle curiosity. Rather, it has been the kind of curiosity that asks “why could that not be done better?”; “why could that not be done more efficiently?”.
Bill Haydon is of English descent, his mother and father having come to this country just before Bill was born. He was raised in an environment which has a reputation for producing healthy citizens. He spent most of his growing years in the Midwest – Downers Grove, Wheaton and Hinsdale, Illinois. He learned early to do for himself – delivering newspapers, mowing lawns, setting pins in a bowling ally and even ringing the carillion in the church tower. And he helped his older brother to build “wireless” receivers.
His was a productive curiosity. He says he was “always” interested in electric motors and clocks. He remembers that his mother used to stop the old, loud-ticking, wooden pendulum clock in the kitchen because it made her nervous. This made him wonder if the ticking of the clock was really necessary. It occurred to him that there did not seem to be any necessary relationship between ticking and proper timekeeping. So he became interested in the possibility of a silent electric clock. Young as he was – 22 at the time-he knew that this would have to be independent of frequency of current supplied by the local power company because, as many may remember, very few power companies had accurate frequency control of their AC current at that time.
You may recall that H.E. Warren, father of the synchronous electric clock in this country, had already been manufacturing his “Telechron” clock which we know today as a product of General Electric. But in Haydon’s home town, the current supplied by the local utility company made the “Telechron” clock act in an erratic way – gaining 10 minutes one day, loosing 15 the next. It occurred to Haydon that it might just be possible to combine the principles of simple harmonic motion normally used in clocks or watches and still have the clock operate from the power of the local utility company, but independent of the inaccurate frequency control. He found that this could be done with a coil spring attached to an induction motor. This was the basis of Haydon’s first patent, No. 1,801,958 issued April 21, 1931, entitled “Reversible Single Phase Induction Motor”.
Haydon’s solution for this accomplishment was truly ingenious. He used a conventional electric, shaded-pole motor and simply removed the shading coils so it would run in either direction. To this he attached a coil spring. He found that after the motor was initially started in one direction by hand, it would wind up the spring and stall; than be started by the spring in the reverse direction until the spring again stalled the motor and started it in the original direction. This action would continue, with each oscillation having a simple harmonic motion characteristic, providing a time base independent of the frequency of the alternating current supply.
Unfortunately, this unit was much too large and too expensive for use in household clocks. Since no motors of suitable size or characteristics were available, Haydon started to work in his home workshop to develop an extremely induction motor which might prove to be suitable, both in cost and size, for home electric clocks. He soon found that the problem of miniaturization was extremely difficult because the torque characteristics of induction motors decreased rapidly as size was reduced. He also found that no engineering data was available on which to base a sound design. So Haydon went “back to school”. He studied basic motor theory for a considerable length of time at the John Creerar Reference Library in Chicago where he absorbed the works of Charles P. Steinmetz and others.
After finishing his studies, Haydon then built several models of miniaturized induction motors in his own workshop. In so doing, he quickly learned that he was not going to find the solution to the problem by using normal ”squirrel cage” motors. He failed a few times, but his failures finally jogged him into a realization that the performance characteristics he was seeking might be obtained by using permanent magnet steel for the rotor instead of the original squirrel cage induction type rotor. He built many models and finally accomplished the desired operating characteristics. This motor design is covered by Patent No. 1,935,208 and related patents.
Again Haydon’s solution was ingenious, for the motor was capable of oscillating continuously when connected to a hair spring. It would also run synchronously in one direction without the hair spring. This made it usable either independent of, or dependent on the frequency of current supplied by the local utility company.
By this time, Mr. Warren was aware of the problem he faced in trying to sell his synchronous clocks, and he had developed systems for controlling the frequency of the current supplied for the clocks by the power companies by regulating their generator speeds with a Master clock. Many power companies began to regulate their frequency not only for the purpose of encouraging the use of synchronous electric clocks as an ideal 24 –hour per day uniform load on their lines, but also for the purpose of enabling them to interconnect one power company’s output with that of another power company. This was the beginning of what we call today, the superpower networks. Naturally Mr. Warren’s clock now had a much larger market. And the old time spring clock manufacturers watched their sales drop drastically.
In 1930, Haydon licensed The Waterbury Clock Company, which became Timex-
, in Waterbury, Connecticut, to manufacture his motor for the use in clock movements (either independent of or dependent on the frequency of the supplied current). Haydon himself acted as design engineer to expedite clock production. Prototypes of both models were made. Waterbury management decided that the greatest market potential existed for straight synchronous clocks - those dependent on the frequency of the supplied AC current. This decision was based on the previous success of the Warren lock; it was cheaper to produce and needed no adjusting for accurate timekeeping. Production started with non self-starting clocks to avoid infringement on Warren’s “Systems” patents. Theoretically, his patents his patents would be infringed by anyone who plugged a self-starting synchronous clock into an electric outlet in a home. A short time later an association of old clock companies found a similar “system” had been used in Cologne, Germany, several years prior to Warren’s invention and patent. So the Haydon motor was made self-starting by attaching “shading” coils to split sections of pole pieces.
Several million clocks later, Haydon tried unsuccessfully to get Waterbury (Timex) to go deeper into the motor timer field. He knew there would be an industrial and consumer demand for the conveniences these little motors offered – automatic oven and furnace controls for the home; automatic streetlights, traffic lights, etc. During the same period, Waterbury management decided to accept Haydon’s offer of a non-exclusive license at a reduced royalty. This decision gave Haydon the right to manufacture the motor himself or to license any manufacturer to do so.
In 1933, Haydon left Waterbury Clock (Timex) and set up his own development shop under the name of Haydon Laboratory. His major works were improving his self-starting timing motors and developing clock movements suitable to use with his motor. He hoped to be able to license his invention to other clock and timer manufacturers. Additional capital became necessary and Haydon was introduced to C.H. Winship, Jr., the President of the Lektophone Corporation, which provided the necessary financing and acted as an agent in granting manufacturers’ licenses. During this period, the Haydon self-starting motor was improved many times in power output and proved superior to anything on the market. Various timer manufacturers were interested in using the Haydon motor but preferred to buy rather than manufacture. So in the midst of a depression, Haydon Manufacturing Company was formed although certain Lektophone stockholders took a dim view of going into the manufacturing business.
In 1937, Haydon Manufacturing Company was incorporated with Charles Winship as President, and Bill Haydon as Vice President in Charge of Manufacturing and Engineering. Barely adequate financing was provided by several former Lektophone stockholders. Haydon assigned patent rights to the Company for a minority stock interest. The advantages of his motor were easily recognized and demand was created. Also, Haydon’s patent situation was strong enough to give the Company a good margin over competition – both in cost and in motor performance.
The Sessions Clock Company had been using a motor which required a good deal of adjustment to make it run properly in order to keep accurate time. They were so impressed with the simplicity and straightforward design of the Haydon motor, they took a license for use in all their clocks.
During 1938, Haydon Manufacturing leased facilities from Sessions in Forestville, Connecticut, in order to expand operations to meet the demands of the entire timer industry. The Haydon motor became a standard in the industry because of its fundamental design concept, efficiency of output and low cost of manufacture.
By 1941, the Haydon Manufacturing Company was producing approximately 15,000 motors per week. Licenses included General Time Instrument, Westinghouse, International Register, Autler Electric, Paragon Electric, as well as Sessions.
Shortly after Pearl Harbor, Charlie Winship resigned to serve in the Navy, and Bill Haydon became President of the firm bearing his name. With Government prohibition of product manufacturing for civilian applications starting at the beginning of World War II, volume by September 1942, had fallen to approximately 1/10 of what it had been in September 1941.
Haydon then started designing a variety of products for wartime use – time delay relays, repeat cycle timers and other electromechanical devices. Most of these designs were classified. Even the Haydon management did not know their end use. At one point, they were advised that their time relay was part of the M-9 Gun Director manufactured by Western Electric and developed by Bell Labrotories. This time delay relay protected the vacuum tubes used in the automatic computer for target tracking.
One of Bill Haydon’s most important personal and direct contributions to the war effort was both exciting and dramatic because, in a sense, he made it possible for the Army Air Corps (now the Air Force) to continue its accurate bombing of strategic and tactical targets. Specifically, reference is made to the Farnsworth Automatic Bombing Control System which improved upon and replaced the Norden Bombsight. Farnsworth had assumed that almost any clock company could furnish one important component, a small gear reduction unit, with the necessary clutches and differentials. After searching the entire clock industry, it was discovered that their assumption was very wrong. Their entire program for the new electronic bombing system was in jeopardy for the lack of this specialized component. Bill Haydon personally designed the gear reduction unit for this program. And in spite of loss of personnel to the Armed Forces, controls of wages by the War Labor Board and lack of capital due to a previous drop in peacetime volume under government control, nevertheless, this company, under Haydon’s guidance, was able not only to meet Farnsworth’s demands effectively, but able to increase the normal motor and timer business to a sales volume double what it had been at the beginning of the war.
All the business consisted of supplying Haydon designs of patented motors and timers to the military and electronics industries.
Although the examples cited above of this man’s contribution to the war effort would seem to be substantial enough for him to rest on, he made another great contribution to our total war effort. It was an invention so comprehensive that it affected almost every aspect of our military operation on land, on the sea and in the air. Haydon invented a DC motor (covered by patent No. 2,513,410) which was used in aircraft, tanks, submarines, and a variety of portable military equipment so that all of this equipment could be operated by battery supply. This further enabled the company to provide all of its timers for battery operation which had previously required alternating current for synchronous motor operation.
The company’s growth flowing from these technological development was paralleled by increased earnings and increased need for cash for enlarged operations. Originally cash was extended by the banks on Haydon’s personal endorsement. Later, working capital was obtained by V loans.
Bill Haydon was a minority stockholder and an employee of the Haydon Manufacturing Company, buy no agreement existed regarding any other inventions which were actually Haydon’s personal property, with the Company having only a “shop right”. His request for royalties or additional stock as compensation for additional patents or patentable products was denied by the Board of Directors despite Haydon’s varied contributions. As a result, it was agreed by all to sell the Company to General Time Instrument Company.
Haydon granted General Time a non-exclusive, royalty-free license under the DC motor invention covered by U.S. Patent No. 2,513,410. He also assigned previous patents under which the Haydon Manufacturing Company held exclusive licenses. General Time offered to set up a research and development laboratory, if Haydon would head it, but he decided the time had come to set up his own business again.
In 1945, he formed The A.W. Haydon Company whose prime objective was building timers and control devices for aircraft and other government applications.
Haydon soon found that DC timer applications required accuracies far in excess of anything obtainable by the use of any DC motors the available, even with the best centrifugal governors attached. The only way to obtain the precision timing accuracy required for many applications was to use a crystal oscillator, frequency divider, amplifier, and synchronous motor, the total cost of which was in the neighborhood of $1,000. This was about the size of a loaf of bread and weighed approximately 15 pounds. Such units were made by other companies but only for applications requiring extreme precision.
It was obvious to Haydon that there was a definite need for a much smaller, lighter and less expensive method of producing accurate speed drives for timers and control mechanisms. So, he developed what is well known in the industry as a Chronometric Governor for his DC motors (covered by patent No. 2,523,298). It was less than 2” in diameter, ½” thick, weighed two ounces and sold as part of the motor to which it was attached for approximately $60.00.
This invention gave The A.W. Haydon Company the capability of furnishing precision timers for de-icing, cabin pressurization, microwave tuning, potentiometer time drives and components for electronic controls for guidance systems for missiles plus numerous other applications in the aircraft and electronics fields. Perhaps more importantly, this invention established Haydon’s ability to adapt his inventive genius to the times by moving successfully from the air age to the future space and atomic age. After this invention, The A.W. Haydon Company rapidly became a leader in the manufacture of timers and controls for all types of applications requiring operation on direct current. Sales rose on a parabolic curve, doubling or more than doubling each year.
By 1951, sales had reached three and one-half million dollars. The excess profits tax then in effect siphoned off cash and made the sale of the company appear prudent while it was still in a sound financial position. That year, The A.W. Haydon Company was sold to North American Phillips. The A.W. Haydon Company (Connecticut Corporation) was not dissolved, but was used to handle all sales of the new Division of Phillips. Bill Haydon continued as chief executive of the new Phillips’ Division, as well as president of the sales corporation. At approximately the same time Haydon Switch, Inc. was formed to exploit a precision snap switch which Haydon had invented, but did not want to sell outright (typified by patents 2,700,079; 2,773,954; 2,773,955 and other patents). This company was jointly owned by Bill Haydon and Phillips. Haydon was the substantial majority stockholder.
In December 1954, Phillips acquired control of Reynolds Spring Company by the transfer of assets of The A.W. Haydon division from Phillips to Reynolds Spring for stock. The combined operation was renamed Consolidated Electronics Industries Corporation of which Haydon was made vice president and director.
Consolidated Electronics subsequently acquired: Price Electric Company, Frederick, Maryland; Technical Electronics Company, Culver City, California. In addition to assuming all management functions of these companies; Haydon contributed materially to the miniaturization of many Haydon products. (A miniature motor developed by Bill Haydon, less than one-inch diameter and weighing less than two ounces circled the world in the Vanguard II Satellite.) He also invented a number of improved timers and motors and a micro-miniature synchronous motor the size of two aspirin tablets (U.S. Patent No. 3,113,231)
Consolidated Electronics also acquired an 80% interest in the Sessions Clock Company of which Haydon became president and chief administrative officer in addition to his other duties. This Company was suffering from sharply falling sales, poor product design and inadequate internal operations control. Still it appeared to fit generally with Consolidated Electronics line of products. It was used as a manufacturing arm for timers which Haydon also designed (U.S. Patent No. 3,106,620). These timers were designed for use in telephone systems. At the same time, Haydon simplified the clock movements produced at Sessions, reducing the number of movements needed from sixteen down to three. He contributed certain patentable inventions to accomplish this. As a result of all his work, the Sessions operations were turned around and their tax loss credits absorbed before they expired. Haydon continued as president of Sessions until it became stabilized as a successful unit.
Around 1956, while negotiating a new 5-year employment contract with Consolidated, Haydon became interested in digital counters, and with the consent, knowledge and approval of Consolidated Electronics, he formed the Haydon Instrument Company. Haydon, himself owned virtually all the stock in this Company. Purpose of the Company was to manufacture a novel type of counter specifically designed to overcome the difficulties encountered in the usual Geneva or transfer pinion type mechanism. This counter is typified by U.S. Patent No. 3,069,083. It incorporates a planetary gear mechanism for advancing the digits so the driving torque is extremely low and uniform. The digits transfer instantaneously and align themselves more accurately as well as having a capability of high speed counting beyond the range of Geneva or transfer pinion type counters. These Planetgear® counters are sold not only as counters for instrumentation but variations thereof are sold as digital clocks and running time meters for telephone systems, the latter having considerable potential in the new WADS and WATS systems.
Bill Haydon also invented a Printed Circuit motor – an extremely simple, yet reliable, DC motor. It uses a printed circuit which comprises the entire winding and commutator in a single flat printed circuit disc. Surprisingly enough, the motor field is a simple doughnut-shaped piece of ferrite magnet material. This motor is covered by U.S. Patent No. 25,305. Because of its compactness, simplicity, reliability, and apparent low cost in volume production, the North American Phillips Company took exclusive royalty-paying licenses throughout the world except in the United States and Canada. The Haydon Instrument Company retained manufacturing rights in the United States and Canada except in the timer and shaver fields, which Phillips’ and Consolidated. Electronics’ licensed fields of use. Photocircuits Corporation also found the Haydon was the prior inventor of the basic concept of a Printed Circuit motor patent.
For ten years (1951-1961), Haydon and the Phillips-Con Electron family enjoyed a highly profitable and enormously productive and agreeable association. Concurrently, Haydon had additionally formed Haydon Switch, Inc. as well as The Haydon Instrument Company previously mentioned. At this juncture, Haydon made the decision to form Haydon Industries, Inc., with the idea that this company would work as a consultant firm with the four Consolidated Electronics’ operations – the companies which Haydon had managed so successfully. Haydon planned that his new company would also serve his Instrument and Switch Companies through consulting contracts. As a consequence of this decision, Haydon was relieved of the obligation of future patent assignments to Phillips, corporate responsibility, management of multi-divisions, etc. He was able to organize a small group for the more efficient handling of the multiplicity of administrative and advisory functions which he had personally handled. This group consisted of his old friend; Charlie Winship (who after World War II had become Vice President of Phelps Dodge Refining Corp.), E.R. Kambrich, formerly assistant to the President of the Garrett Corporation, and G.O. “Fred” Hoffman, Sales Manager of The A. W. Haydon Company.
Concurrently, discussions were held with the objective of combining all of the above corporations into a single entity. The pursuit of these objectives, deeply committed to by Haydon, resulted in some policy differences between Haydon and the Con Electron-Phillips family. In the deepest friendliness, both personal and corporate, in late September 1962, it was decided that it served the best interests of all to terminate the consulting contract for Haydon to purchase Philips’ share of Haydon Switch, Inc.
In October 1963, Haydon merged his personally controlled companies into one entity. The Haydon Instrument Company and Haydon Industries, Incorporated were merged with and into Haydon Switch, Incorporated, the name of which was changed to Haydon Switch & Instrument, Inc. This completely independent corporate entity was organized with a net worth of slightly over one million dollars. It subsequently purchased 70% of Aetna Maintenance, sold to Aetna its going business with a license and gave it the name Haydon Switch & Instrument, Inc. 30% of HSI’s stock is publicly held and traded over the counter. The original company assumed the name Tri-tech, Inc. and still owns 70% interest.
Products manufactured are precision snap switches, pressure switches, counters and digital clocks, running time meters, open frame monitors, BIG INCH® synchronous and stepper motors and step servos, timers and time delay relays.
These products have already demonstrated their considerable value to the United States military posture. Additionally, they are already important and are becoming increasingly and more comprehensively important in civilian applications – automation, computing, communications, and used generally through the aircraft, electronics, instrumentation and control, and missile industries, with commercial applications now resulting in over 80% of HSI’s sales volume.
The same proven management team is “on deck” – Charles Winship, VP/Secretary-Treasurer, and Earl Kambrich, VP/General Manager. Bill Haydon is quick to emphasize that the real strength of HIS comes from the wonderful support provided by all the employees of the company who have demonstrated their capability, loyalty and interest, time and time again over many years.
Haydon takes no interest in inventions unless they appear to have practical application and good profit potential. He applies his imagination with equal intensity to selling, manufacturing and management functions.
New patented products have been added to the HIS line, notably BIG INCH® synchronous and stepper motors, step servos, and DC Chronetic® motors, interrupters and improvements in counters and clocks. The latest additions to the HIS line are binary readout clocks and counters, which hold very promising future potential. These are largely the inventive contributions of A. W. “Bill” Haydon who, all told, has obtained more than 60 U.S. Patents with many corresponding foreign patents, and several more U.S. and foreign patents pending.
Bill says inventors would be more successful if they developed a better understanding of business, and business executives would make more progress if they developed a better understanding of inventions and patents. With both of these tools at hand, and adequate capital, Bill is confident of HSI’s future growth.
Asked about his age, Bill is frank to admit he’s over 65, the normal retirement age. But he says that’s fine for anyone that wants to retire. He’s made it Company Policy not to force retirement on anyone who is healthy, capable and wants to work. He says what he calls “Forced Retirement Syndrome” has put the quietus on many a good man. That’s one of the many reasons he left the Phillips-Con Electron family. He did not want someone else to tell him when to retire. He points to Churchill, DeGaulle, Edison, and many others who made great contributions after reaching age 65.
With his keen interest in HSI’s present activities and his strong belief in HSI’s future, he says his work was never so interesting and challenging and plans to work at least until HIS has realized what he believes to be its full growth potential.
Also interesting and challenging is Bill’s home life. Happily married, his wife, Jean, has made him the proud father of three young boys, Johnny, Billy and Jimmy, all of whom he wants to see realize their full growth potential too.
Patents Issued to A.W. Haydon
A.W. Haydon has made literally hundreds of inventions. Here, giving the Title, United States Patent Number and Date issued, are listed only those for which patents have been issued.
April 21, 1931 Reversible Single-Phase 1,801,958
May 2, 1933 Alarm Clock 1,906,716
May 2, 1933 Alarm Clock 1,907,106
Nov. 14, 1933 Electric Motor 1,
Oct. 16, 1934 Electric Motor
and Clock 1,977,184
Oct. 16, 1934 Electric Motor 1,977,185
Oct. 16, 1934 Electric Motor 1,977,186
April 2, 1935 Electric Motor 1,996,375
April 30, 1935 Electric Clock 1,999,692
May 7, 1935 Electric Motor
and Clock 2,000,516
July 28, 1936 Electric Motor
Aug. 24, 1937 Electric Clock 2,091,117
Dec. 16, 1941 Electric Clock 2,266,198
Nov. 3, 1942 Gear Stud
July 11, 1944 Electric Motor
and Method 2,353,305
of Making same
Dec. 9, 1947 Clock
April 13, 1948 Radio Time
May 2, 1950 Electric Motor
and Method 2,505,829
of Fabricating same
May 9, 1950 Electrical
Timing System 2,506,784
July 4, 1950 Electric
Sept. 26, 1950 Motor Speed
Jan. 13, 1953 Electrical
Jan. 18, 1955 Snap Action
March 27, 1956 Motor Speed
April 30, 1957 Motor Speed
Dec 11, 1956 Snap Action
Dec 11, 1956 Snap Action
Aug 12, 1958 Electric
Rotating Machinery 2,847,589
Dec 9, 1958 Resettable
Drive Mechanism 2,863,281
for Potentiometer or like
Jan 13, 1959 Motor Speed
March 17, 1959 Sealed Switch and 2,878,348
Feb 21, 1961 Cyclic
Switching Mechanism 2,972,662
March 28, 1961 Open Face Clock 2,976,674
March 28, 1961 Snap Action Switch 2,977,436
Sept 12, 1961 Portable
Dec 12, 1961 Chronometric
March 6, 1962 Timing Mechanism 3,023,567
Oct 9, 1962 Motor Speed
Dec 18, 1962 Planetgear
Transfer Counter 3,069,083
Dec 25, 1962 Electric
Rotating Machinery Reissue
Jan 15, 1963 Fastening
July 2, 1963 Motor for
Electric Clock 3,096,452
Oct 8, 1963 Cam-Actuated
Dec 3, 1963 Hysteresis
Dec 1, 1964 Alarm Buzzer
for Clock 3,158,986
Dec 22, 1964 Oscillating
Magnet to 3,162,793
Govern Motor Speed
May 11, 1965 Magnetically
Coupled Constant 3,183,426
Nov 11, 1965 Adjustable
Cycling Times 3,220,264
for Aircraft Deicers
Feb 8, 1966 Resettable
May 24, 1966 Synchronous
June 14, 1966 Counter 3,255,962
June 14, 1966 Synchronous
Aug 2, 1966 Method for
Fabricating Electrical 3,264,152
Oct 18, 1966 Electric
Rotating Machinery 3,280,353
Nov 29, 1966 Time Totalizer
April 11, 1967 Timer-Actuated
Feb 20, 1968 Stepper Motor 3,370,189
Feb 11, 1969 Cam-Operated
Sep 23, 1969 Synchronous
Feb 10, 1970 Cylindrical
Stepper Motor 3,495,107
Feb 10, 1970 Small Permanent Magnet Motor 3,495,111
Feb 10, 1970 Electric
Rotating Machinery 3,495,113
Feb 16, 1971 Rotor Stator
Feb 22, 1972 Clock System 3,643,420
May 23, 1972 Time Delay Relay 3,665,348
July 26, 1972 Cam Actuated Switch Assembly 3,679,988
Aug 22, 1972 Clock System 3,685,278
Sep 12 1972 Clock System 3,690,059
May 15, 1972 Clock Mechanism 3,732,685
Aug 14, 1973 Counting Device 3,752,965
Nov 6, 1973 Electric Rotating Machine 3,770,998
Jan 22, 1974 Counting Device 3,787,663
July 22, 1975 Counting Device 3,896,298
Aug 5, 1975 Clock Setting Mechanism 3,897,700
Sep 2, 1975 Method of apparatus for controlling
the performance of timed functions 3,903,515
Sep 30, 1975 Electric Rotating Machine 3,909,646
Oct 28, 1975 Timing Device 3,916,377
Nov 18, 1975 Clock Des.237,696
Nov 11.1975 Digital Clock or other Counting
Device with Resilient Coupling
Means to the Drive Train 3,918,252
Nov 18, 1977 Electric Rotating Machine 4,004,168
Aug 9, 1977 Clock Drive Apparatus 4,040,247
Dec 18, 1984 Magnetic Switch 4,489,297
there are several U.S. Patent applications being prepared
and pending as of the
date of printing of this booklet (1972).