Europe during the 13th century. They were usually installed in towers and used bells to sound the hours. Their purpose was to sound the canonical hours, the times during the day when prayers were said. They were weight driven mechanisms, and eventually smaller versions started to be made for use in houses. At some point, dials and hands were added to indicate the time, with a chime marking out the hours.
Of all the decorative arts objects produced by the Pennsylvania Germans, none more typifies their social aspirations of success than does the tall clock. Many of the owners were farmers whose lives were regulated by the natural rhythms of tending livestock and crops. They had little need to break days into hours and minutes, evidence that clocks were far more than just timepieces.
Clockmaking was a complex trade involving several craftsmen. Generally, the maker’s name painted on the clock face is that of the craftsman who made or assembled the works. The case was ordered from a cabinetmaker. When purchasing a case, customers could select from a wide variety of decorative elements, including woods, moldings, veneers, and inlays, depending on how much they wished to spend. This was true of the several clockmakers known to have been working in this region in the late 18th and early 19th centuries. The clocks seen here are representative of the types of clocks and cases available to local purchasers.
Since the tall clock was often the most expensive household furnishing, they were often kept in the parlor, where visitors would be sure to see them. Tall clocks remained fashionable well into the first quarter of the 19th century but their popularity began to decline in the 1830s. This decline was due, in part, to the introduction of mass-produced and relatively inexpensive shelf clocks.
Clockmaker Eli Bentley was born in February 16, 1752, near a town called Doe Run, in West Marlborough Township, Chester County, Pennsylvania. On November 20, 1772, Eli married Mary Hunter. Mary’s cousin was Thomas Shields, a clockmaker in Philadelphia. It is believed that Shields taught Bentley the clockmaking trade.
Bentley moved to Taneytown around 1782. The earliest mention of Bentley appears in the Maryland Orphans Court Proceedings for November 20, 1782, which recorded that 17-year-old John Riley had been indentured to Bentley for a term of four years and that Bentley was to teach him “the art and mistery of a Clock and Watch maker.”
In 1787, Bentley purchased a house on Lot #16, near the square in Taneytown. There, Eli and Mary raised seven children: Harriet, Joseph, John, Ann, George, Belinda, and Eli. Bentley died in 1822. He was survived by his wife, six of his children, and a legacy of magnificent timepieces.
Tall Case Clock, 1782-1790
Works by Eli Bentley
Gift of Anne Franklin Boyle Alexander, 2004.16.1
The engraved brass dial indicates that this was one of Bentley’s earliest Maryland pieces. The vine design decorating the spandrels and the inlaid design on the waist door of this clock are similar to that seen on many Pennsylvania pieces, showing that Bentley has not yet broken away from his Pennsylvania roots.
It is believed that the original owner of this clock was Daniel Saylor Hering who owned a mill at Beaver Dam (near Johnsville) in Frederick County. The donor’s aunt, Lillian A. Franklin, acquired the clock in the early 1940s.
Tall Case Clock, 1785-1810
Works by Eli Bentley
Gift of Arlene H. Williams, in memory of Mary & David Nusbaum of Taneytown, 2000.5.1
Although never inexpensive, the cost of a tall clock could vary greatly depending on the quality of the works and case. Cased in native walnut with wrought iron “rat tail” door hinges and fitted with 30-hour works, this example was among the least costly pieces by Eli Bentley. The names of most of the cabinetmakers who worked with Bentley remain unknown but the extensive use of wooden pegs instead of nails in this case indicates that this cabinetmaker was trained in the German woodworking tradition. The clock descended in the Nusbaum family of Taneytown.
Tall Case Clock, c.1970
Works and Case by C.R. Nusbaum
Gift of Kenneth Nusbaum Hull, 99.22.21
Though tall clocks are not as common as they once were, they are still very popular. Old clocks are passed lovingly from generation to generation and new clocks are still being produced. Though many of the modern tall clocks are mass-produced, some are still individually made by craftsmen. Nusbaum appears to have based the design of this clock on those of Eli Bentley. The rat tail hinges are very similar to those on the clock donated by Mrs. Williams which came from the Nusbaum family.
Tall Case Clock, dated 1815
Works by Eli Bentley
Gift of Victor Weybright, 69.2.1
Both the clock case and dial are neoclassical in proportions and ornament. The use of mahogany and veneers, the high scrolled pediment, French bracket feet and the fluting of the chamfers, collonettes and plinths are typical of the finer cases made in western Maryland. The painted moon dial covering the eight-day works features ovals in each corner.
Joseph and Mary (Kalb) Biggs, the original owners of the clock, built a handsome stone house in Keysville in 1814. Bentley charged $95 for this impressive clock the following year, evidence that the Biggs’ clearly wanted the best furnishings for their new home.
Tall Case Clock, 1810-1820
Works by Eli Bentley
Museum Purchase, 97.83.1
Clockmakers expressed their creativity in their work and no two pieces are exactly the same. For this clock, Bentley used American motifs including a ship flying an American flag as a design element on the moon phase dial. Handsome gilded decorations complete the design. This example is similar to the clock Bentley made for Joseph Biggs in 1815. The cases of the two clocks are similar in style with minor differences in the decorative trim. This clock was acquired by a family in New Jersey where it kept time for at least a century.
Tall Case Clock, c.1810
Works by Eli Bentley
Gift of William Truman Ensor, 2015.16.1
Alexander McAlister and his wife, Margaret Flemming, are believed to have been the original owners of this clock. The first documented owners were Scott William McAlister and his wife, Anna Mary Bohn. Their daughter, Idaline Pearl, inherited the clock. Idaline married William G. Segafoose of Uniontown. It passed to their son William, and then to his son Charles. Charles left the clock to William Ensor in 1999. It came to HSCC from Ensor’s estate in 2015.
Tall Case Clock, c.1810
Probably New York
Gift of Thelma Walden Littlefield Shriner, 94.7.192
The owners of this clock, Robert Wyndham Walden and his wife Caroline, brought the clock with them when they moved to Maryland from New York in 1872. The Waldens settled in Middleburg and established Bowling Brook Farm, where they bred and trained racehorses. Later, their granddaughter (the donor) displayed the clock in the parlor of her home, Hard Lodging, in Union Bridge.
Tall Case Clock, c.1815
Bequest of Granville E. Bixler, 93.5.1
John H. and Laura P. Fuss were the original owners of this magnificent clock. The cabinet features a carved shell motif, fluted columns with brass bases and capitals, a broken arch pediment with carved rosettes and three flame finials. The donor owned two tall clocks, which he inherited from members of his family. He bequeathed both clocks to the Historical Society.
Tall Case Clock, c.1810
Works by Jacob Hostetter
Bequest of Granville E. Bixler, 93.5.2
Jacob Hostetter was born on May 9, 1754, near York, Pennsylvania. He served his apprenticeship in clockmaking with Richard Chester of Hanover. In 1788 he is listed in the tax records as a clockmaker. In 1797, Hostetter became a member of the Pennsylvania General Assembly where he served until 1802. From 1802 through 1823 he operated a brass foundry in Hanover and was producing clockworks on the two lots he owned on Chestnut Street opposite the Neas House. He also served in the U.S. House of Representatives from 1818 through 1821. In 1825, Hostetter moved to Ohio. He died on June 29, 1831, in New Lisbon, Columbiana County, Ohio.
Hostettler was a prolific craftsman and over 100 of his clocks are known to survive. In addition, three of his sons became clockmakers.
John C. and Jesse Englar Buckey were early owners of this timepiece. Although not inexpensive, the relatively plain walnut case and 30-hour works indicate the clock was purchased by someone of middling wealth.
Tall Case Clock, c.1815
Works by Jacob Wolf
Gift of Theodore F. Alban, in memory of his grandparents, Theodore F. “Bud” & Angela Boylan Shaeffer, 2003.3.1
Jacob Wolf is an elusive figure. Though J. Thomas Scharf stated in his History of Western Maryland (1882) that “Jacob Wolf at an early period manufactured clocks, many of which are still in use over the country,” few Wolf clocks are actually known to survive. According to American Clockmakers and Watchmakers (by Sonya L Spittler, Thomas J. Spittler, and Chris H. Bailey), Wolf was born in 1795 and died in 1865. Wolf moved to Waynesburg, Pennsylvania, around 1817 and then was in Hanover around 1817-1820. An advertisement in the Star of Federalism newspaper from 1818 lists him as “having opened shop in Uniontown.” Why he moved so often and where else he lived and worked is not known at this time. This is the only clock by Wolf known to have the Westminster signature.
Tall clocks are very delicate and can be top-heavy and unstable. This clock was damaged when it tipped and fell into another piece of furniture in the mid-1900s. Repairing the damage to the door necessitated refinishing the case. It was probably at that time that the glass cracked and the front feet were replaced.
Tall Case Clock, c.1810
Works by John Fessler, Sr.
Bequest of Walter Dana Rudy, 97.49.1
John Fessler, Sr., was born in Switzerland in 1759 and immigrated with his parents to America in 1771, first living in Philadelphia, then Germantown, and then Lancaster. It is likely that Lancaster is where he apprenticed in the clockmaking trade. From 1777-1782 he fought as a private in the Continental Army. After the War, Fessler settled in Frederick, Maryland, and in 1783 he opened a clockmaking and silversmithing business at the corner of West Patrick and Publick (now Court) Streets. His career spanned several decades and included a partnership with his son John, Jr., as John Fessler and Son (1817-1820).
This clock originally belonged to John and Catherine Daub of Frederick County who were married in 1804. Their granddaughter, Laura Routzahn Rudy, brought the clock with her to Mt. Airy in 1912. Laura left the clock to her son, Walter, who willed it to the Historical Society. In the 1970s, the clock was shortened to fit into a Baltimore apartment. The waist of the clock was shortened and the ogee feet removed to reduce the overall height of the piece. The clock has also been refinished.
Tall Case Clock, c.1810
Possibly John Fessler, Sr.
Gift of Thelma Walden Littlefield Shriner, 94.7.262
Though John Fessler, Sr., is believed to be the maker of this clock, the piece is not signed and the maker will probably never be determined absolutely. Frederick was home to a number of clockmakers including Elijah Evans, Daniel Forrer, Frederick Heisely and George Schnertzel. The donor purchased the clock and displayed it in her home, Hard Lodging, in Union Bridge.
Gradually spring-driven clocks were made smaller and smaller as their makers showed off their skills. Eventually they became small enough that they could be carried as ornaments, initially on a neck chain, and then hanging from the belt. These were the first watches.
The earliest watches were not very accurate and were more novelties for the very wealthy than useful timepieces. One of the earliest references to what could be called a wristwatch was an armlet given to Queen Elizabeth I by the Earl of Leicester as a New Year’s gift in 1571. Most of the early wristwatches were elaborately decorated, heavily jeweled, and intended to be worn by women.
Men thought wristwatches were too small to be properly engineered to keep accurate time. They were also prone to damage by shock, or contamination with dust and moisture due to their exposed location on the wrist. Most importantly, they were viewed as jewelry that were only to be worn by women.
A gentleman who wanted a timepiece carried a pocket watch, tucked inside his vest pocket and secured with a chain that fastened it to his buttonhole. Innovations in the mid- to late-19th century—including the advent of the railroad, factories, and electricity, and the standardization of time zones in Europe and the United States—increased the demand for watches as more and more people lived by the clock.
The pocket watch remained the most common personal timepiece until into the 20th century. Wristwatches began to overtake pocket watches during World War I when army officers began to use wristwatches for easier access—rifling through a pocket for a watch was not advisable in the chaos of the trenches. Wristwatches were briefly known as trench watches because of this military connection. Returning soldiers brought their fondness for wristwatches home with them. In April 1919, the Tulsa World proclaimed that “The war has made the world safe for men who wear wrist-watches.” By World War II, pocket watches were obsolete.
Watch chain, 1870
Gift of Margaret Whittlesey Werling, 96.78.62
This watch chain was made from the hair of Mary J. Haines (1849 – 1923). Dr. Jacob J. Weaver, Jr. (1848 – 1937), wore it to his wedding to Mary on December 5, 1870, in Philadelphia. The Weavers set up housekeeping in Uniontown and in 1874 built a house at 3411 Uniontown Road. Their home is now known as the Weaver-Fox house. Jacob and Mary had one child, Florence Eyster Weaver (1871 – 1942).
Watch chain, 1870
Gift of Mary Fox Whittlesey, 84.45.2
This watch chain made from the hair of Mary J. Haines Weaver, wife of Dr. Jacob J. Weaver, Jr. Weaver was born in Uniontown. He attended Pennsylvania College (now Gettysburg College), the University of Maryland Medical School (graduating in 1870), and then joined his father’s practice in Uniontown at the age of 22. He retired in 1887 to go into banking and politics. Weaver helped establish the Carroll County Savings Bank in Uniontown and the Birnie Trust Company in Taneytown. He sat on the board of directors of the Carroll County Fire Insurance Company and the First National Bank of Westminster.
Hunting Case Pocket Watch, mid-19th century
M.I. Tobias & Co.
Gift of Beulah F. Hoptroff, 81.1376.15
Michael Isaac Tobias was one of the best-known British watchmakers. His firm – M.I. Tobias & Company – produced watches of several grades that sold for a wide range of prices. The company also made timepieces specifically for the American market with designs aimed at American tastes. This example features an engraving of William Penn signing a treaty with the Native Americans. Tobias’ work was so popular that imitations flooded the market, using names such as “M.J. Tobias.” These imitations often used inexpensive Swiss movements and had cases of inferior quality.
Many pocket watches did not have a cover over the glass face. These “open face” watches were vulnerable to being scratched or broken. Some makers began putting a hinged, metal cover on their pieces to protect the face from damage. These became popular with fox hunters in England and became known as “hunting” (or “hunter”) cases. “Hunting case” became a descriptive name for any watch that had a cover.
Hunting Case Pocket Watch, 1891
American Waltham Watch Company
Gift of Anna Margaretta McCoy, 2000.53.15
In 1853, a watch factory opened in Boston and began doing business as the American Horologe Company. The company changed its name to the Boston Watch Company in 1853, and opened a new, larger factory in Waltham, Massachusetts, the following year. In 1885, the company became the American Waltham Watch Company. In 1906 the company was renamed the Waltham Watch Company. By the late 1950s, the firm had produced over 35 million watches.
The small size of this watch and the decorative floral designs on the case indicate that it was a lady’s watch. Margaretta Reistine Jones McCoy was the original owner of this watch. Margaretta married Thomas L. Jones and they had three children: Thomas, Catharine, and Mary. After Thomas died in 1851, Margaretta married Edmund S. McCoy that same year. The McCoys had one child: a son, Edmund. The McCoys owned a farm near Oakland Mills.
Pocket Watch, late 19th century
Gift of Anna Margaretta McCoy, 2000.53.17
The delicate design of this watch identifies it as a lady’s watch. It belonged to Catharine Jones [1842-1916]. She was the daughter of Thomas and Margaretta Jones. Catharine never married and lived out her life on the farm in Oakland, Carroll County, that belonged to her step-father Edmund S. McCoy.
Mantel Clock, 1848-1850
William L. Gilbert & Co.
Gift of Burrier L. Cookson, 39.4.1
In the first quarter of the 19th century, Connecticut became a center for manufacturing mass-produced mantel clocks with brass works. William L. Gilbert was one of the foremost Connecticut clockmakers. Gilbert’s first company was founded in 1828 in partnership with his brother-in-law, George Marsh. A decade later, Gilbert was in business with Chauncey Jerome, whose brass movements formed the heart of Gilbert’s new mantel clocks. While Gilbert’s clocks were inexpensive timepieces designed for the average consumer, they were not simple, bare-bones devices. Those with wood cases were often made of oak while many of the metal cases were bronzed. Many of the clocks were ornately decorated with vine-draped pillars, elaborate finials, and floral scrolls.
This example is typical of Gilbert’s ogee clocks, named for the curved molding that surrounds the front of the clock. It has a reverse painted tablet depicting P.T. Barnum’s mansion “Iranistan.” Built in Bridgeport, Connecticut, in 1848, the fanciful three-story structure was a mix of Byzantine, Moorish, and Turkish decorative elements. It had numerous porches and arches, and was topped by multiple onion domes. Constructing the house cost Barnum almost $150,000. A fire (believed to have been caused by repairmen working in the building) destroyed the property in 1857.
Mantel Clock, 1845-1848
William L. Gilbert & Co.
Gift of Thelma Walden Littlefield Shriner, 94.7.16
Robert Wyndham Walden [b. August 2, 1843 – d. April 28, 1905] was one of the most successful trainers in thoroughbred horseracing during the last quarter of the 19th century. In 1872 Walden and his wife, Caroline [b. August 7, 1844 – d. June 10, 1925], moved from New York to Middleburg, Carroll County, where they established Bowling Brook Farm to breed and train thoroughbred racehorses. This clock was purchased by Walden’s father, George, in the 1840s when the family resided at Walden Towers in Virginia. Walden inherited the clock and took it to his home in New York. Walden brought the clock with him to Maryland and proudly displayed it in Bowling Brook.
Mantel Clock, Patented 1877
E. Ingraham & Co.
Gift of Mildred Tarkington, 2004.8.15
E. Ingraham & Company was formed in 1860, succeeding several earlier clock-manufacturing firms in which casemaker Elias Ingraham (1805-1885) had been involved. Having originally purchased its movements from various sources, in 1865 the company established its own movement-making facility. Elias Ingraham designed a variety of popular cases and case features for the firm, receiving 17 patents between 1857 and 1873. Many of the most popular cases featured rosewood veneer and were made in several sizes to offer a range of prices.
Mantel Clock, 1903
Western Clock Manufacturing Co.
Gift of Mildred Tarkington, 2004.8.16
In December 1885, Charles Stahlberg and others from Waterbury, Connecticut, formed the United Clock Company in Peru, Illinois, to manufacture clocks based on a technological innovation by Stahlberg. The innovation involved the use of molded lead alloys in the movements and gear assemblies, reducing the amount of expensive brass used in the clocks. In 1888, the company went bankrupt and reorganized as the Western Clock Manufacturing Company. The firm produced a variety of inexpensive clocks, including alarm clocks. By the early 20th century, it was selling over 500,000 clocks each year. In 1909, the company introduced the famous “Big Ben” alarm clock which is still made today.
This clock was advertised in the company’s 1902 trade catalog as the “Vendome” style. The original wholesale price to dealers was $2.75. The price for retail customers buying the clock in their local store would have been slightly higher.
Alarm clock, c.1900
Gift of Thomas S. Gordon, Jr., 2017.13.5
The alarm clock is a derivation of early tower clocks that sounded a chime at specific times. German and English clockmakers were adding chimes to their weight-driven timepieces as early as the 16th century. The earliest recorded American alarm clock was made by Levi Hutchins in New Hampshire in 1787. However, it had limited appeal as it only struck at 4:00 a.m., the time Hutchins had to get up for work. The first mechanical alarm clock in which the striking time could be set by the user was patented in France in 1847. In the late 1870s, as more and more people started working in factories and offices that required arriving at work on a strict schedule, small alarm clocks for the bedside became popular.
This clock originally came from the family of Edward A. Chrest (1 September 1865 – 14 September 1934) who owned a livery stable at 197-299 E. Main St., Westminster.
Mantel clocks in the “French Taste,” 1852-1870
Gifts of Thelma Walden Littlefield Shriner, 94.7.24, 94.7.109
These two unsigned and unmarked mantel clocks are representative of the “Second Empire” or “French Napoleon III” style, popular during the period from 1852 to 1870. Louis-Napoleon Bonaparte (1808-1873), nephew of Napoleon I, was elected the first President of the French Republic in December 1848. A coup d’etat in December 1852 transformed the Republic, with the support of the bourgeoisie, once again into a hereditary empire. Napoleon III and his Empress Eugenie championed the 18th century “royal” style of Louis XVI, ushering in a new “Imperial Age.” The Second Empire expressed its social diversity and newfound prosperity in a wide array of bold stylistic experiments ranging from Greek Revival to Gothic Revival and encompassing Orientalism and Japonism. Innovative and of superior quality, these luxury goods dominated the French consumer market. Americans coveted these products as being “in the best of taste.” These two clocks, therefore, reflect the consummately executed synthesis of styles—an encyclopedic approach to ornamental sources.
Both clocks represent the idiosyncratic nature of design during this period and are unique in their forms. The gilt and ormolu bronze clock with a Louis XVI oval casing displays interlaced “c” scrolls, surmounted by a Neo-Classical urn and standing on a base with oriental flora motifs. More common after 1840, Arabic (rather than Roman) numerals in a Neo Gothic-style mark the hours on this clock’s white enamel face. This example, like so many clocks of the period, has an eight-day striking movement and rings hours and half hours. The architectonic form of the bronze clock with a verdigris patina illustrates a pastiche of Moorish, Neo-Grec, and Renaissance revival styles. The clock is driven by a pendulum mechanism. Roman numerals designate the hours.
The Cost of Time
Throughout the early 19th century, clocks often appeared in estate inventories as one of the most expensive household furnishings. A clock might represent almost five percent of a family’s net worth. Still, the values of clocks varied widely.
In 1817, Major Alexander McIlhenny of Uniontown recorded in his journal that he paid Eli Bentley of Taneytown $60 for a clock. In a separate transaction, he paid Uniontown cabinetmaker Jacob Christ $40 for a mahogany clock case, bringing the total cost for the clock to $100. This must have been an extraordinary piece.
Finding a journal entry such as McIlhenny’s is rare. Much of what we know about the value of timepieces comes from estate inventories. Among the possessions of Jacob Sherman (builder of the Sherman-Fisher-Shellman House), devised to his widow by his estate in 1822, was a “clock and case” valued at $45. Though worth far less than McIlhenny’s clock, this was still the most valuable piece of furniture in Sherman’s estate.
In 1816, David Fisher’s estate included an eight-day clock valued at $55. The next most valuable furniture in Fisher’s estate was “two mahogany side tables” valued at $20. John Yingling, who died in 1816, also owned an eight-day clock, this one valued at $50.
In 1827, John C. Cockey’s widow inherited a “time peace” (most likely a tall clock) valued at $25. While the household linens and carpets were worth more, the timepiece was the most valuable piece of furniture. Josiah Stevenson, who also died in 1827, owned a clock and case valued at $35.
Like tall clocks, the value of pocket watches varied depending on the material they were made from and the quality of the workmanship. In 1816, Thomas Adelsperger bequeathed to his wife a silver watch worth $10. However, in 1827, Mrs. John Cockey inherited a gold watch valued at $150 from her husband.
Tall clocks remained fashionable well into the first quarter of the 19th century. Their popularity declined throughout the century as inexpensive mantel clocks flooded the market. Mantel clocks were introduced in the late 18th century in an attempt to make smaller, less expensive timepieces that more people could afford to own. In 1815, Eli Terry began mass-producing them in his Connecticut factory. The inexpensive clocks were such a huge success that in 1852 there were over 30 clock manufacturers across the country.
By the mid-1800s advertisements for stores selling clocks and watches appeared in Carroll County newspapers. Baltimore firms such as Gabriel Clark, Canfield Brothers, and Joseph M. Walter were regular advertisers. In June 1842, William Wolf began advertising in the Carrolltonian that he had commenced business as a clock- and watch-maker in Yingling’s Hotel on Court Street in Westminster. Starting in 1865, William Moore offered timepieces for sale at his new store near the railroad. Now, consumers no
longer dealt with the craftsman making one-of-a-kind timepieces but rather with a retailer selling mass-produced pieces.
By the end of the 19th century, mail-order companies made it possible for customers to select from a wide variety of goods, no matter where they lived or what their budget. Sears, Roebuck, and Company’s 1897 catalog offered five pages of mantle and wall clocks ranging in price from $.57 to $8.25. But the once-fashionable tall clocks were nowhere to be found.
The same catalog also had 27 pages of pocket watches ranging in price from $.98 (for a nickel-plated model) to $72.85 (for a 14-karat gold model). The fashion-conscious gentleman could also choose from a variety of gold or silver watch chains and watch charms that came in dozens of designs including the emblems of many fraternal organizations such as the Masons, the Odd Fellows, and the Knights of Pythias.
Timekeeping can be as simple as counting “one Mississippi, two Mississippi.” Or it can be as complex as measuring the changes in the cesium atoms in an atomic clock. In all types of timekeeping devices, the goal is counting the intervals of something that occurs repeatedly, with as little variation as possible. Take a brief look at the evolution of timekeeping.
Sundials divided days into equal parts. As the sun moves across the sky, shadows change in direction and length, so a simple sundial can measure the length of a day. It was quickly noticed that the length of the day varies at different times of the year. Another discovery was that sundials had to be specially made for different latitudes because the sun’s altitude in the sky decreases at higher latitudes, producing longer shadows than at lower latitudes.
1400 B.C. — 1300 B.C.
WATER CLOCK (EGYPT)
Water clocks (also called clepsydras) let water drip out of (or into) a vessel at a nearly constant rate. Markings measured the passage of time. Later versions evolved in Greece and China. Changes in temperature and humidity could affect the device’s accuracy.
The Egyptians improved upon the sundial with a merkhet (also known as a star clock), one of the oldest known astronomical instruments. It uses a string with a weight as a plumb line to obtain a true vertical line. A pair of merkhets were used to establish a North-South direction by lining them up one behind the other with the Pole Star. Viewing the plumb lines through the sight made sure the two merkhets and the sight were in the same straight line with the Pole Star. It marked off nighttime hours by determining when other stars crossed the meridian.
An hourglass (also called a sandglass) consists of a precisely measured amount of sand in a sealed glass container. When the device is tipped over, the sand pours slowly through the pinched center at a constant rate until all of the sand in the top flows to the bottom. The turning of the hour glass sends the grains again from top to bottom at the same rate, thus the timer or glass will measure time equally whichever side is turned up. If the sand is measured, one can use the glass to measure the passage of time. The accuracy of the device can be adjusted by adding or removing sand. These devices were simple to make and had no parts to wear out but could only measure short periods of time and required constant attention.
100 B.C. — 1300
IMPROVED WATER CLOCKS (GREECE, ROME, CHINA)
More elaborate, mechanized water clocks made the flow more constant by regulating pressure; some featured bells and gongs or moved pointers, dials and astrological models of the universe. In 11th century China, a water-driven, roughly 10-meter-tall clock tower powered a rotating celestial globe and opened doors revealing bell-ringing figurines.
CANDLE CLOCK (ENGLAND)
This device kept time as a candle burned past evenly spaced lines or different colors of wax. However, these were not very accurate as the quality of the wax, thickness of the wick and air currents in the room could affect the rate of burning.
960 — 1250
INCENSE CLOCK (CHINA)
The incense in these clocks burned threads of different thicknesses, each attached to a small hanging weight. When the thread burned through, the weight dropped onto a gong, sounding the time.
VERGE-AND-FOLIOT MECHANICAL CLOCK (EUROPE)
The first mechanical clocks appeared in Europe around 1300. These were powered by a weight suspended from a rope or chain that was wrapped around a horizontal axle. To tell time, the weight must fall with a slow uniform speed, but, under the action of gravity alone, such a suspended weight would accelerate. To prevent this acceleration, an escapement mechanism was required. The best of these was called the verge and foliot escapement. Clocks with these devices were accurate enough to mark the hours but not minutes or seconds.
SPRING-DRIVEN CLOCK (GERMANY)
A wound spring was developed during the middle of the 15th century to provide the power for a clock. The tightly wound spring released energy as it uncoiled and turned the hands on the clock. However, these clocks were notoriously inaccurate: the clock ran faster when the spring was tightly wound, and then ran slower as the spring unwound.
Pocket Watch (Italy and Germany)
The pocket watch evolved from the spring-driven clock. Early versions were called pocket clocks. They were heavy, drum-shaped brass cylinders, several inches in diameter, engraved and ornamented. They had only an hour hand. The face was not covered with glass, but usually had a hinged brass cover, often decoratively pierced with grillwork so the time could be read without opening.
PENDULUM CLOCK (THE NETHERLANDS)
Dutch scientist Christiaan Huygens made the first clock that was regulated by a pendulum. The consistent pace of the pendulum’s swing regulated the movement of the escapement. Huygens’ pendulum clock had an error of less than 1 minute a day.
MARINE CHRONOMETER (ENGLAND)
The purpose of a chronometer is to measure accurately the time of a known fixed location, for example Greenwich Mean Time (GMT). This is particularly important for navigation at sea. Knowing GMT at local noon allows a navigator to use the time difference between the ship’s position and the Greenwich Meridian to determine the ship’s longitude. In 1761, John Harrison, a carpenter and instrument maker, developed a clock powered by a bi-metallic spring that was not affected by the movement of the ship or the high humidity at sea. His 1764 version kept time accurately to about one-fifth of a second per day. Early chronometers resembled large pocket watches. Later versions were installed in protective wood cases.
QUARTZ CLOCK (UNITED STATES)
The quartz clock uses an electronic oscillator that is regulated by a quartz crystal to keep time. When electricity passes through quartz, the mineral vibrates. Inside the clock, a battery sends a small electrical charge through a piece of quartz. This causes the quartz to vibrate at a very precise rate. The vibration drives the hands or powers an LCD display. Early quartz clocks were delicate, expensive, and very large—almost as large as a refrigerator.
An atomic clock is an extremely accurate timepiece that depends for its operation on an electrical oscillator regulated by the natural vibration frequencies of an atomic system. When exposed to certain frequencies of radiation, the electrons that orbit an atom’s nucleus jump back and forth between energy states. Inside an atomic clock, atoms are funneled down a tube where they pass through radio waves. If the frequency of the radio waves is just right, the atoms “resonate” and change their energy state. A detector at the end of the tube keeps track of the number of atoms reaching it that have changed their energy state. The detector feeds information back into the radio wave generator that synchronizes the frequency of the radio waves with the peak number of atoms striking it. Other electronics in the atomic clock count this frequency. A second is ticked off when the frequency count is met.
QUARTZ WATCH (JAPAN)
Gradual improvements in the technology of quartz clocks allowed them to be made smaller and smaller. Japanese company Seiko introduced the first quartz watch. The first quartz watches were very expensive, costing as much as a car. Today, the vast majority of watches have a quartz mechanism and prices have dropped to only a few dollars.
HOW THINGS WORK SECTION
WHY IS A TALL CLOCK TALL?
A clock is a machine in which a device that performs regular movements, in equal intervals of time, is linked to a counting mechanism that records the number of movements. The number of movements translates to units of time passing. In a tall clock, that moving device is the pendulum.
A pendulum is a rod hanging vertically from its top end. What makes a pendulum useful in a clock is that it always takes the same amount of time to make a complete swing. If there were no friction or drag (air resistance), a pendulum would keep moving forever. In reality, friction and drag steal a bit of energy from the pendulum with each swing, and it gradually comes to a halt. But even as it slows down, it keeps time. The pendulum doesn’t climb as far, but it covers the shorter distance more slowly—so it actually takes exactly the same time to swing.
The tall clock requires power to keep the pendulum swinging. That power comes from the weights. A pair of weights hang from a wire that is wrapped around an axle. If not controlled in some manner, the weights would rapidly fall to the bottom and the clock would not run. To allow the weights to fall at a controlled, regulated speed, a gear on the axle connects to a mechanism called the escapement. The escapement has two teeth that lock into a gear on the weight axle. It is connected by an arm to the top of the pendulum. As the pendulum swings, it rocks the escapement back and forth. As the escapement rocks, it briefly releases the gear, allowing it to “escape” and rotate slightly before the escapement re-engages. It is this engaging and disengaging of the escapement that creates the “tick tock” sound associated with pendulum clocks. With each turn of the weight axle, a small amount of wire unwinds, lowering the weight a short distance and providing some energy to keep the pendulum swinging.
A delicate set of timekeeping gears use the turning of the axle to turn the clock’s hands. Since the escapement rocks at a consistent pace, the hands also move at a consistent rate and the clock will keep accurate time.
1. The pendulum swings back and forth at a constant pace. At each end of its swing, the pendulum rocks the escapement.
2. As the escapement rocks, it releases and re-engages the main gear.
3. When released by the escapement, the gear turns one notch, turning the main axle.
4. With each movement of the gear, the weights drop at a gradual, controlled rate. The controlled falling of the weights feeds energy back through the system to keep the pendulum swinging. When the weights reach the bottom, the clock will stop.
HOW DOES A WATCH WORK?
Like most timekeeping devices, watches require power to make them work. Today, most watches are electronic devices powered by batteries. But earlier watches were mechanical. The mechanism in a mechanical watch is similar to a spring-driven clock.
The power in a mechanical watch comes from the mainspring. Winding the watch tightens the coils of the mainspring. Gears prevent the spring from rapidly uncoiling and connect to a device called the escapement. The escapement rocks back and forth, slowly releasing the energy from the mainspring and transferring it to the balance wheel.
The balance wheel—which rotates at a constant rate—is attached to a set of gears that turn the watch’s hands. The rate at which the balance wheel rotates can be adjusted to make the watch run faster or slower and keep accurate time.
1. The winding stem coils the mainspring.
2. The mainspring stores energy as it coils.
3. A set of gears prevent the mainspring from uncoiling.
4. The escapement rocks back and forth, allowing the gears to turn at a regulated pace and gradually release energy from the mainspring.
5. The balance wheel rotates at a constant rate and transfers the energy from the escapement to a smaller set of gears.
6. The timekeeping gears are connected to the hands on the watch face, causing them to rotate around the face and indicate the time.
For almost 200 years, clocks were driven by falling weights. However, the development of the coiled flat spring in the 15th century meant that a spring could be used to drive the clock instead of weights. Now timepieces could be made small enough to stand on a table instead of standing on the floor or hanging on a wall, and they could be moved around while they were running.
The mechanism that makes a mechanical clock work is called the movement. Inside the clock is a coiled thin strip of metal called the mainspring. A key that fits into the clock coils the mainspring. The spring stores energy as it coils tighter and tighter. If the mainspring were wound and then released on its own, it would immediately unwind and expend all its energy. To prevent this, the mainspring is connected to a set of gears that control the rate at which the spring unwinds. These gears are connected to the hands of the clock. As the gears turn, so do the hands, indicating the passage of time.
Clockwork mechanisms can also be used to power other devices such as music boxes, early phonographs, and wind-up toys.