Self Winding Clock Company

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Clock in Grand Central Terminal on the information kiosk. The clock has four 24-inch (61 cm) dials and was made by the Self Winding Clock Company. It was installed in 1913. Photo from December 23, 2009.

The Self Winding Clock Company (SWCC) was a major manufacturer of electromechanical clocks from 1886 until about 1970.[1] The Self Winding Clock Company clock mechanisms were truly revolutionary because the spring that powers the clock was not wound by hand but with an electric motor. The SWCC of New York was one of the first companies in the United States to successfully employ electric energy to power a clock. The winding motor is attached to, and mounted below, the conventional clock works. The unique feature of their patented clock mechanism is the automatic rewinding of the main spring each hour by the small electric motor. A contact switch mounted on the clock's center shaft is activated after the clock has run for one hour and the main spring is rewound one revolution. This rewinding occurs each hour. The power for the motor is supplied by batteries and the batteries last about one year before needing to be replaced. This clock mechanism never needed to be wound by hand and this eliminated the concern that someone may forget to wind the clock. Hence the company name, The Self Winding Clock Company.

Selling exact time—a new industry[edit]

The motivation for establishing the Self Winding Clock Company was early entry into a revolutionary and potentially profitable new industry. The product this new industry was selling was "exact time". This became possible following the development of the telegraph. The first marketers of time were observatories. The observatories used their celestial equipment to measure exact time and then transmit a time signal via telegraph lines to subscribers. This was done for a fee. In the 1850s and 1860s, communication and travel between cities became more common. The practice of observing local time was becoming obsolete and the need for everyone to agree to the exact time became essential. The railroads recognized that safety was related to precise timing and all timepieces in a given area must be set to the same time. The heads of the major railroads met on October 11, 1883, in Chicago to adopt our Standard Time System. The country was divided into four time zones with exactly one hour difference in each zone. The four time zones are part of the worldwide system of Standard time—a set of 24 somewhat equally spaced meridians tied to the daily cycle of daylight and darkness. It is based in Greenwich, England and termed Greenwich Mean Time.

Observatories had been selling exact time since the 1850s and transmitting the noon time signal via telegraph lines to customers, usually nearby cities and railroads. The signals were transmitted to sounders as second ticks and pauses that culminated in a noon time signal. The subscriber's clock could then be manually adjusted to exactly noon. For providing this exact time service there was a monthly or yearly charge. Observatories were affiliated with colleges or universities with the exception of the United States Naval Observatory (USNO), which is affiliated with the United States government. Competition for customers was keen between observatories, but by 1887 the USNO was recognized as the provider of Observatory Standard Time by the General Time Convention that had been convened by the country's railroads.[2] This ended the intense competition for providing exact time. Western Union's time service distributed the time signal via its telegraph lines. Western Union had years of experience in transmitting USNO time signals and ultimately emerged as the provider of nationwide telegraph lines for the noon time signal.

The competition for selling exact time necessitated developing a reliable master clock and auxiliary clocks. Connecting multiple clocks via electrical wires in a system had proved feasible. Two slightly different master clock-slave clock concepts emerged. The first entailed the use of an electro-mechanical "synchronizer" to forcibly bring the minute hand to the 12 position exactly on the hour. Each of the clocks in this system used a complete clock mechanism with the addition of a synchronizer. A central clock (master clock) sent the synchronizing signal along telegraph lines to each clock, thereby assuring that all clocks displayed exactly the same time. The individual clocks in this system had self-contained batteries and required three volts direct current (DC) to operate. The batteries for the synchronizing system transmission were located in a central office. The use of the mechanical synchronizer was the design of Chester H. Pond and his associates as they formed the SWCC in 1886. A second approach to synchronized time transmitted along wires was to connect a master clock to relatively simple secondary clocks (slave clocks). The slave clocks did not have complete clockworks but simply a mechanism that, when energized electrically from the master clock, would advance the clock hands one unit of time. The slave clock would display exactly the same time as the master clock. Slave clocks were much less complicated to manufacture and required little or no servicing. Initially they were more prone to failure. Each of the slave clocks had wires that connected to the master clock. The master clock in this system required 24 volts DC to both wind the master clock and as a source of current to advance the hands of the slave clock. These master-slave systems were more suited for individual buildings such as schools or factories, rather than locations that were great distances apart. A master-slave clock system was developed and marketed in 1886 by Charles D. Warner and operated as the Standard Electric Time Company. The accuracy of the master-slave system was dictated by the accuracy of the master clock and reliability of the slave clocks. Over the years, correction systems were developed for the master-slave systems that rendered the systems very reliable and accurate. In the first three decades of the 20th century, many more companies entered the time-selling business. When one considers the entire country, the number of synchronized clock systems installed in learning institutions, factories, businesses, government installations, transportation facilities, and other buildings, was enormous. Many hundreds of thousands of slave clocks and probably tens of thousands of master clocks were manufactured, sold, installed and serviced by people involved in the exact-time-for-sale business.

Synchronized time systems were originally powered by batteries and most up through the 1950s operated on low-voltage direct current. Eventually the new systems were designed to operate on alternating current. For many years, selling exact time was a major industry. Presently, the Global Positioning System (GPS) space-based satellite navigation system provides our exact location and time information. Slave clocks, which were an integral part of the synchronized time system, now are often replaced with battery operated clocks that are linked to the atomic clock signal for synchronizing. Selling exact time's importance as an industry has been superseded.

Founding of the Self Winding Clock Company[edit]

The Self Winding Clock Company clock movement was patented by one of the company founders, Chester Henry Pond (1844–1912) in 1884 (Patent No. 308,521). Pond was also a principal in the Gamewell Fire Alarm-Telegraph Company.[3] He was not only an accomplished instrument maker but also a pioneer in the developing field of electricity. With these two skills he successfully designed a small electric motor and matched it with a conventional clock mechanism to create the reliable SWCC movement.

In addition to the electric motor to wind the SWCC movement, in 1886, Chester Pond patented a correction device that used an electric current to activate a mechanical lever attached to the clock movement. This correction attachment would move the clock hands precisely to the hour (Patent No. 339,688). If the clock is not absolutely accurate, it would be corrected when receiving the hourly time signal over a telegraph line from a master clock calibrated to the US Naval Observatory. This correction was referred to as synchronizing, and many SWCC clocks were fitted with this option.

The original SWCC factory was located at 205 Willoughby Avenue in Brooklyn, New York.[4] This site was across from the Pratt Institute, and now is part of the Pratt Institute campus. Charles Pratt (1830–1891), the founder of Pratt Institute, was also one of SWCC’s original founders and the company started business in his buildings. The SWCC factory remained in Brooklyn until they moved to 75 Varick Street, New York at some time in the 1950s, to apparently make room for expansion at the Pratt Institute. In addition to doing the clock manufacturing in Brooklyn, SWCC had business offices at various locations in New York city throughout its long history.

Self Winding Clock Company clock movements[edit]

photograph of F movement
SWCC Style F Vibrator movement
photograph of the seven styles of SWCC movements
Seven styles of SWCC movements. Styles C and B from 1886 to Style F from 1898

When Self Winding Clock Company started producing clocks, the vast majority of the actual clock movements were made by the Seth Thomas Clock Company and the remainder were made by the E. Howard & Co.. The most expensive clocks could be equipped with the higher grade movement made by E. Howard. SWCC then fitted their motor-winding components and synchronizing apparatus to the movements. The movements were mounted in cases of various designs, often in case styles similar to those of companies like Seth Thomas and E. Howard.[5] The SWCC appears to have been manufacturing their own clock movements by 1892, for they are all stamped "Self Winding Clock Co". Earlier movements were stamped with Seth Thomas or E. Howard markings.[6]

The unique feature of SWCC clocks was the fact that the clocks were wound electrically. The success of SWCC depended upon the clocks being reliably wound every hour without failure. The hourly winding motor was the one element of the clock that was most likely to fail. Over a span of about 15 years, the design of the SWCC movements went through a series of modifications aimed at improving reliability. The first six different styles all had the winding motor added to the SWCC movement. The final design, termed the "F" movement or Vibrator movement, was a major improvement. This movement, with minor modifications, was used for the next 60 plus years. In this design, the motor proved to be much more reliable and was now an integral part of the movement rather than added on below the clock works. The "F" movement motor employed a vibrating up and down motion rather than rotary motion to re-wind the mainspring.

SWCC imprinted all of their movements with serial numbers. The serial numbers were used for inventory purposes and were assigned in ascending order. It is possible to approximately date the time of manufacture of a movement based on the serial number.[7] The first "F" movements were made in 1898 and were made into the 1940s. However, it is not possible to automatically date a particular clock by the movement serial number. SWCC had a practice of exchanging clock movements rather than servicing a movement and then returning it to the same clock. This results in rarely finding a SWCC clock with its original movement. Identification tag numbers also often do not match movement serial numbers because the tags were not changed when the movement was exchanged. The total number of "F" movements manufactured could be confusing. The lowest serial numbers are in the 33,000 range and the highest is in the 402,000 range. There were large numbering gaps and it has been calculated that probably around 200,000 movements were produced.[8]

The Self Winding Clock Company and the Western Union Time Service[edit]

SWCC Western Union clock
SWCC Western Union clock interior

The relationship between the two separate companies began with an agreement between Self Winding Clock Company and Western Union (WU) being entered into in June 1889.[9] This agreement was for the transmission of time signals over Western Union telegraph lines to synchronize clocks made by Self Winding Clock Company. SWCC owned the clocks and WU installed and maintained them for a monthly fee, ranging from $1.25 to $2.00 per clock per month. SWCC was paid a percentage of the rental fee for providing clocks for the WU customers.[10] If the clock movements required major repairs, they were sent to a SWCC repair facility and a replacement movement was installed by WU at the customer location. The partnership between SWCC and WU ended in 1963 when, as part of a lawsuit settlement, WU purchased all the rental clocks from SWCC. By the late 1960s, the time-service business had run its course and ceased to be profitable. Most of the clocks were simply abandoned. These clocks are sought after by many clock collectors.

Notable clocks created by the Self Winding Clock Company[edit]

The SWCC clock's were usually used in synchronized time systems. Time systems that consisted of many clocks linked electrically to a master clock. The majority of the systems were installed in businesses, factories, banks, schools, and universities. Many railroads also relied on SWCC synchronized clock systems. Some clocks were sold as individual timepieces but most clocks were a part of time systems. SWCC offered many very elegant designs for their clocks and the clocks could be purchased to match any decor. These were essentially catalog items. There were however many special one-of-a-kind clocks and clock systems that were installed by SWCC. These were intended to be very important architectural statements. Two of the most significant installations were the clocks in the Grand Central Terminal and the enormous four-dial clock and lighting system for the Metropolitan Life Insurance building. The two pictured clocks of the Grand Central Terminal and the outside clocks on the Metropolitan Life Insurance building were just part of each property's very complex synchronized time systems. Grand Central Terminal had a master clock that controlled all the clocks at the terminal. Metropolitan Life had two separate master clocks. One controlled the motors for the four outside clocks, rang the bells in the bell tower and controlled the spectacular and very complex outside lighting system. Another SWCC master clock controlled 184 slave clocks throughout the original building. Complex SWCC synchronized systems were also installed in the London Underground. The underground installation started in 1905 and eventually included about 600 SWCC clocks.[11]


  1. ^ Elmer G. Crum & William F. Keller, ed. (1992). 150 years of Electric Horology. Chicago, IL: Midwest Electric Horology Group. pp. 60–61. 
  2. ^ Bartky, Ian R. (2000). Selling The True Time. Stanford, CA: Stanford University Press. p. 173. 
  3. ^ Bartky, Ian R. (2000). Selling The True Time. Stanford, CA: Stanford University Press. p. 167. 
  4. ^ De Santis, Chris (2006). Clocks of New York. Jefferson, NC: Mc Farland & Company. p. 46. 
  5. ^ Blackwell, D. J. (1986). C.H. Bailey, ed. 1887 Self Winding Clocks Catalog reproduction. Bristol, CT: American Clock & Watch Museum. 
  6. ^ Bloore, J. Alan (May–June 2012). "The Self Winding Clock Company and the Ubiquitous Style "F" Vibrator Movement". NAWCC Watch & Clock Bulletin. 54/3 No. 397: 252. 
  7. ^ Singer, J. J. (February 1981). "Request: Self-Winding Clock Co.". NAWCC Bulletin. No. 210: 70. 
  8. ^ Bloore, J. Alan (May–June 2012). "The Self Winding Clock Company and the Ubiquitous Style "F" Vibrator Movement". NAWCC Watch & Clock Bulletin. 54/3 (397): 259. 
  9. ^ Bartky, I. R. (2000). Selling The True Time. Stanford, CA: Stanford University Press. p. 273. 
  10. ^ Bartels, M. W. (1977). "The Self-Winding Clock Company and The Western Union Time Service". NAWCC Bulletin. No.191: 632. 
  11. ^ Burton, D. (August 1999). "Timekeeping on the London Underground". NAWCC Bulletin. No.321: 457. 

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