Jun 122014


Today is the birthday (1806) of John Augustus Roebling, a German-born U.S. civil engineer. He is famous for his wire rope suspension bridge designs, in particular, the design of the Brooklyn Bridge. I have a personal interest in Roebling because I lived for 25 years in the old telegraph office on the Delaware and Hudson Canal adjacent to the remains of an aqueduct over the Neversink River that Roebling designed in 1848.

Roebling was the youngest of four children. He was baptized in the Lutheran church Divi Blasii in Mühlhausen. As a young boy he played the bass clarinet and the French horn. He also exhibited great artistic talent for sketches and paintings. His father owned a small tobacco shop, but the business was insufficient to provide livelihood for all three sons. Roebling’s sister Friederike Amalie married Carl August Meissner, a poor merchant in the town, and his oldest brother Herman Christian Roebling prepared to take over the tobacco shop.

At first Roebling attended the gymnasium in Mühlhausen. Recognizing his intelligence at a young age, Roebling’s mother, Friederike Dorothea Roebling arranged for him to be tutored in mathematics and science at Erfurt by Ephraim Salomon Unger. He went to Erfurt when he was 15. In 1824 he passed his surveyor’s examination and returned home for a year. In 1824 he enrolled for two terms at the Bauakademie in Berlin where he studied architecture and engineering under Martin Friedrich Rabe (1765–1856), bridge construction and foundation construction under Johann Friedrich Dietlein (1782–1837), hydraulics under Johann Albert Eytelwein (1764–1848), and languages. Roebling also attended lectures by the philosopher Hegel. Roebling developed an interest in natural philosophy and many years later he worked on a 1,000 page treatise about his own concepts of the universe.

In 1825 Roebling got a government job at Arnsberg, Westphalia, working on military road building for four years. During this period he made sketches for suspension bridges. In 1829 he returned to his home to work out his final thesis and prepare for his second engineer examination. For unknown reasons, he never took the examination.

On May 22, 1831, Roebling left Prussia with his brother Carl and Johann Adolphus Etzler, the technological utopianist. Economic mobility and career advancement were difficult for engineers in Prussian society. This unfortunate state of affairs had been brought about by the Napoleonic Wars, which lasted until 1815. This period in European history left Prussia with political unrest, as authoritarian governments took the places of democratic ones. Etzler had ideas about creating a utopia in the United States, but disputes arose en route, and the group split. Roebling and his brother purchased 1582 acres (6.4 km²) of land on October 28, 1831, in Butler County, Pennsylvania with the intent to establish a German settlement, called Saxonburg. Most of the other settlers remained with Etzler. The John Roebling House at Saxonburg was listed on the National Register of Historic Places in 1976.


John Roebling and his brother arrived in the United States at an interesting time. The nation was in the later stages of an economic boom, which ended in the Panic of 1837. Farmers were deeply affected by it. Transportation between eastern industrial hubs and frontier farming markets had become a matter of both national and popular interest. Many transportation projects were underway near the location he chose for his colony, but instead of continuing as an engineer, he took up farming. After five years he married Johanna Herting, a tailor’s daughter. Agrarian work did not appeal to John Roebling, and the colony attracted very few settlers. In 1837, after the death of his brother and the birth of his first child, he returned to engineering as a vocation.

Roebling’s first engineering work in the U.S. was devoted to improving river navigation and canal building. He spent three years surveying for railway lines across the Allegheny Mountains, from Harrisburg to Pittsburgh, for the state of Pennsylvania. In 1840 he wrote to suspension bridge designer Charles Ellet, Jr., offering to help with the design of a bridge near Philadelphia:

The study of suspension bridges formed for the last few years of my residence in Europe my favorite occupation … Let but a single bridge of the kind be put up in Philadelphia, exhibiting all the beautiful forms of the system to full advantage, and it needs no prophecy to foretell the effect which the novel and useful features will produce upon the intelligent minds of the Americans.

Roebling began producing wire rope at Saxonburg in 1841. At that time canal boats from Philadelphia were transported over the Allegheny Mountains on railroad cars to access waterways on the other side of the mountains, so that the boats could continue to Pittsburgh. The system of inclines and levels that moved the boats and conventional railroad cars was a state-owned enterprise, the Allegheny Portage Railroad. The railroad cars were pulled up and down the inclines by a long loop of thick hemp rope, up to 7 cm thick. The hemp ropes were expensive and had to be replaced frequently. Roebling remembered an article he read about wire ropes. Soon after, he started developing a 7-strand wire rope at a ropewalk that he built on his farm.


In 1844 Roebling won a bid to replace the wooden canal aqueduct across the Allegheny River with the Allegheny Aqueduct. His design encompassed seven spans of 163 feet (50m), each consisting of a wooden trunk to hold the water supported by a continuous cable made of many parallel wires, wrapped tightly together, on each side of the trunk. This was followed in 1845 by building a suspension bridge over the Monongahela River at Pittsburgh.

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In 1848 Roebling undertook the construction of four suspension aqueducts on the Delaware and Hudson Canal.The images above show the aqueducts at Minisink Ford, High Falls, and Cuddebackville.  The sepia tone is across from my house where there is a small beach, and the bottom image shows the abutments as they are today (my house is to the left).  All but the aqueduct at Minisink were taken down in the early 20th century.

During this period, he moved to Trenton, New Jersey. In Trenton, Roebling built a large industrial complex for wire production. This complex inspired the Trenton, New Jersey motto on Trenton’s Lower Trenton Bridge.


Roebling’s next project, starting in 1851, was a railroad bridge connecting the New York Central and Great Western Railway of Canada over the Niagara River, which would take four years. The bridge, with a clear span of 825 feet (251m), was supported by four, ten-inch (25 cm) wire cables, and had two levels, one for vehicles and one for rail traffic.


While the Niagara bridge was being built, Roebling undertook another railway suspension bridge, across the Kentucky River which required a clear span of 1,224 feet (373m). The anchorage and stone towers were completed, and the cable wire delivered along with the material for the superstructure, when the railway company became insolvent. The bridge construction was halted, and was later finished as a truss bridge.

roebling pitt

In 1859 Roebling completed another suspension bridge at Pittsburgh. Its total length was 1,030 feet (314m), consisting of two main spans of 344 feet (105m) each, and two side spans of 171 feet (52m) each.


The American Civil War brought a temporary halt to Roebling’s work. However, in 1863 building resumed on a bridge over the Ohio River at Cincinnati which he had started in 1856 and halted due to financing; the bridge was finished in 1867. The Cincinnati-Covington Bridge, later named the John A. Roebling Suspension Bridge, was the world’s longest suspension bridge at the time it was finished.


In 1867 Roebling started design work on what is now called the Brooklyn Bridge, spanning the East River in New York. Roebling devised “an equilibrium strength approach, in which equilibrium is always satisfied but compatibility of deformations is not enforced.” This was essentially an approximation method similar to the force method: First, Roebling computed the dead and live loads, then divided the load between the cables and the stays. Roebling added a large safety factor to the divided loads and then solved for the forces. This approach gave a sufficiently accurate analysis of the structure given the assumption that the structure was sufficiently ductile to handle the resulting deformation.


While surveying the site of the Brooklyn tower for the Brooklyn Bridge, the tip of Roebling’s right foot was crushed by a docking boat. After his toes were amputated, Roebling was diagnosed with tetanus and developed lockjaw. He suffered severe seizures and periodically lapsed into a coma before dying in the early morning hours of July 22, 1869 in Brooklyn Heights, New York. Roebling is buried in the Riverview Cemetery in Trenton, New Jersey.

roebling brooklyn

Roebling’s son Washington Roebling and his daughter-in-law Emily Warren Roebling continued his work on the Brooklyn Bridge. His son Ferdinand expanded his wire rope business. His son Charles Roebling designed and invented a huge 80 ton wire rope machine and founded the town of Roebling, New Jersey where the John A. Roebling’s Sons company steel mill was built. His grandson Washington A. Roebling II perished on the RMS Titanic. His great-grandson Donald Roebling was a noted philanthropist and inventor who devised the amphtrack (amphibious landing craft).

Roebling’s home town of Mühlhausen is in Thuringia now in central Germany. Its cuisine is very much what is thought of as prototypically German cooking – wursts, braised beef, pig knuckles, dumplings, and sauerkraut. In a number of places where Roebling designed bridges, such as Cincinnati, there were large populations of German immigrants who brought with them the basics of German-American cooking. Among the most popular dishes, well loved in Thuringia, is sauerbraten – beef marinated in vinegar for days and then slow cooked in the marinade.




2 cups water
1 cup cider vinegar
1 cup red wine vinegar
1 medium onion, chopped
1 large carrot, chopped
1 tbsp plus 1 tsp kosher salt, additional for seasoning meat
½ tsp freshly ground black pepper
2 bay leaves
6 whole cloves
12 juniper berries
1 tsp mustard seeds
3 ½ to 4lb bottom round, whole
1 tbsp vegetable oil
? cup sugar
18 dark old-fashioned gingersnaps (about 5 ounces), crushed


In a large saucepan over high heat combine the water, cider vinegar, red wine vinegar, onion, carrot, salt, pepper, bay leaves, cloves, juniper, and mustard seeds. Cover and bring this to a boil, then lower the heat and simmer for 10 minutes. Set aside to cool.

Pat the bottom round dry and rub with vegetable oil and salt on all sides. Heat a large saute pan over high heat; add the meat and brown on all sides, approximately 2 to 3 minutes per side.

When the marinade has cooled to a point where you can stick your finger in it and not be burned, place the meat in a non-reactive vessel and pour over the marinade. Place into the refrigerator for 3 days. If the meat is not completely submerged in the liquid, turn it over once a day.

After 3 days of marinating, preheat the oven to 325°F/160°C.

Add the sugar to the meat and marinade, cover and place on the middle rack of the oven and cook until tender, approximately 4 hours.

Remove the meat from the vessel and keep warm. Strain the liquid to remove the solids. Return the liquid to the pan and place over medium-high heat. Whisk in the gingersnaps and cook until thickened, stirring occasionally. Strain the sauce through a fine mesh sieve to remove any lumps. Add the raisins if desired. Slice the meat and serve with the sauce and boiled potatoes or dumplings.

Mar 272014


Today is the birthday (1845) of Wilhelm Conrad Röntgen, a German physicist who produced and detected electromagnetic radiation in a wavelength range today known as X-rays or Röntgen rays, an achievement that earned him the first Nobel Prize in Physics in 1901. In honor of his accomplishments, in 2004 the International Union of Pure and Applied Chemistry (IUPAC) named element 111, roentgenium, a radioactive element with multiple unstable isotopes, after him.

Röntgen was born at Lennep in the Lower Rhine Province of Germany, as the only child of a merchant in, and manufacturer of, cloth. His mother was Charlotte Constanze Frowein of Amsterdam, a member of an old Lennep family which had settled in Amsterdam. When he was three years old, his family moved to Apeldoorn in The Netherlands, where he went to the Institute of Martinus Herman van Doorn, a boarding school. He did not show any special aptitude, but showed a love of nature and was fond of roaming in the open country and forests. He was especially apt at making mechanical contrivances, a characteristic which remained with him also in later life. In 1862 he entered a technical school at Utrecht, where he was however unfairly expelled, accused of having produced a caricature of one of the teachers, which was in fact done by someone else.

He then entered the University of Utrecht in 1865 to study physics. Not having attained the credentials required for a regular student, and hearing that he could enter the Polytechnic at Zurich by passing its entrance examination, he took the exam and began studies there as a student of mechanical engineering. He attended the lectures given by Rudolf Clausius and also worked in the laboratory of August Kundt. Both Kundt and Clausius exerted great influence on his development. In 1869 he graduated Ph.D. at the University of Zurich, was appointed assistant to Kundt and went with him to Würzburg in the same year, and three years later to Strasbourg. In 1874 he qualified as Lecturer at Strasbourg University and in 1875 he was appointed Professor in the Academy of Agriculture at Hohenheim in Württemberg. In 1876 he returned to Strasbourg as Professor of Physics, but three years later he accepted the invitation to the Chair of Physics in the University of Giessen.

After having declined invitations to similar positions in the Universities of Jena (1886) and Utrecht (1888), he accepted a post from the University of Würzburg (1888), where he succeeded Friedrich Kohlrausch and found among his colleagues Hermann von Helmholtz and Ludvig Lorenz. In 1899 he declined an offer to the Chair of Physics in the University of Leipzig, but in 1900 he accepted it in the University of Munich, by special request of the Bavarian government. Here he remained for the rest of his life, although he was offered, but declined, the Presidency of the Physikalisch-Technische Reichsanstalt at Berlin and the Chair of Physics of the Berlin Academy.

Röntgen’s first work was published in 1870, dealing with the specific heats of gases, followed a few years later by a paper on the thermal conductivity of crystals. Among other problems he studied were the electrical and other characteristics of quartz; the influence of pressure on the refractive indices of various fluids; the modification of the planes of polarized light by electromagnetic influences; the variations in the functions of the temperature and the compressibility of water and other fluids; the phenomena accompanying the spreading of oil drops on water.


Röntgen’s name, however, is chiefly associated with his discovery of the rays that he called X-rays. In 1895 he was studying the phenomena accompanying the passage of an electric current through a gas at extremely low pressure. Previous work in this field had already been carried out by numerous physicists, working on the properties of cathode rays – the name given to the electric current established in highly rarefied gases by the very high tension electricity generated by Heinrich Rühmkorff’s induction coil. Röntgen’s work on cathode rays led him, however, to the discovery of a new and different kind of ray.

On the evening of November 8, 1895, Röntgen found that, if the discharge tube is enclosed in a sealed, thick black carton to exclude all light, and if he worked in a dark room, a paper plate covered on one side with barium platinocyanide placed in the path of the rays became fluorescent even when it was as far as two meters from the discharge tube. During subsequent experiments he found that objects of different thicknesses placed in the path of the rays showed variable transparency to them when recorded on a photographic plate. When he immobilized his wife’s hand in the path of the rays over a photographic plate, he observed, after developing the plate, an image of her hand which showed the shadows thrown by the bones of her hand and that of a ring she was wearing, surrounded by the penumbra of the flesh, which was more permeable to the rays and therefore threw a fainter shadow. This was the first “röntgenogram” ever taken. Apparently when she saw her skeleton she exclaimed “I have seen my death!”


In further experiments, Röntgen showed that the new rays are produced by the impact of cathode rays on a material object. Because their nature was then unknown, he gave them the name X-rays. Later, Max von Laue and his pupils showed that they are of the same electromagnetic nature as light, but differ from it only in the higher frequency of their vibration.

At one point while he was investigating the ability of various materials to stop the rays, Röntgen brought a small piece of lead into position while a discharge was occurring. Röntgen thus saw the first radiographic image, his own flickering ghostly skeleton on the barium platinocyanide screen. He later reported that it was at this point that he determined to continue his experiments in secrecy, because he feared for his professional reputation if his observations were in error.

Röntgen’s original paper, “On A New Kind Of Rays” (Über eine neue Art von Strahlen), was published on 28 December 1895. On 5 January 1896, an Austrian newspaper reported Röntgen’s discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery. He published a total of three papers on X-rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology, the medical specialty which uses imaging to diagnose disease and other medical ailments.

Numerous honors were showered upon him. In several cities, streets were named after him.  He received numerous prizes, medals, honorary doctorates, honorary and corresponding memberships of learned societies in Germany as well as abroad and, of course, the Nobel Prize in physics of 1901 – the first time it was offered. In spite of all this, Röntgen remained a strikingly modest and reticent man. Throughout his life he retained his love of nature and outdoor occupations. He spent many vacations at his summer home at Weilheim, at the foot of the Bavarian Alps, where he entertained his friends and went on many expeditions in the mountains. He was a great mountaineer and more than once got into dangerous situations. Amiable and courteous by nature, he was always sympathetic to the views and difficulties of others. He was always reluctant to have an assistant, and preferred to work alone. Much of the apparatus he used he built himself with considerable ingenuity and experimental skill.

Röntgen was married to Anna Bertha Ludwig (m. 1872, d. 1919) and had one child, Josephine Bertha Ludwig. Adopted at age 6, in 1887, she was the daughter of Anna’s brother. Röntgen died on 10 February 1923 from carcinoma of the intestine. It is not believed his carcinoma was a result of his work with ionizing radiation because of the brief time he spent on those investigations, and because he was one of the few pioneers in the field who used protective lead shields routinely.


Röntgen did not take patents out on his discoveries, and donated the money for his Nobel prize to the University of Würzburg. With the inflation following World War I, Röntgen fell into bankruptcy later in life, spending his final years at his country home at Weilheim, near Munich. In keeping with his will, all his personal and scientific correspondence were destroyed upon his death.

Sauerbraten is a favorite dish throughout Germany and is served in many German restaurants worldwide.  It is a roast (usually of beef or venison) that has been marinated for 3 to 4 days in vinegar, wine, vegetables, and various spices. Marinating the meat acts as a tenderizer, resulting in tender, soft, juicy meat. There are several regional variations of the Sauerbraten, differing mainly by ingredients of the marinade. Rheinischer Sauerbraten, a specialty of Rhineland-Palatinate (Rheinland Pfalz) and North Rhine-Westphalia (Nordrhein-Westfalen) where Röntgen was born, is the most well known version. Unique to the Rheinischer Sauerbraten is that it is served with a a slightly sweet sauce made with raisins.

Historically, horse meat was used to make Sauerbraten. However, today beef or venison is most often used. As the name suggests, Sauerbraten has a slightly sour flavor. However, it is served with a complementing sauce that balances this out. In some variations, such as the Rheinischer Sauerbraten, the sauce has a slightly sweet flavor. Also, Sauerbraten should be very tender and soft. The marinade serves both as a flavoring agent and as a tenderizer. The longer the meat is able to marinade, the softer and more flavorful it will become.

Sauerbraten is traditionally served with potato dumplings (Klöße or Knödel), red cabbage, and apple sauce. If you don’t care for potato dumplings, Sauerbraten also goes very well with Spätzle, potato pancakes (Kartoffelpuffer or Reibekuchen), and boiled potatoes.


Rheinischer Sauerbraten   (Rhineland Sauerbraten)

1 cup red wine vinegar
1 ½ cups water
½ teaspoon black peppercorns
2 cloves
5 juniper berries
2 bay leaves
2 lb beef roast (boneless)
4-5 slices bacon, minced
2 onions, coarsely chopped
1 carrot, chopped
1 celery stick, chopped
4 tablespoons oil
freshly ground pepper
3-4 lebkuchen
½ cup red wine
¾ cup raisins
apple butter, apple juice, or red current jelly, to taste


Add water and red wine vinegar to a pot. Bring to a boil. Grind down peppercorns, cloves, and juniper berries slightly. Add this, as well as the bay leaves to the boiling liquid. Cook for 2 more minutes, then remove from heat and allow to cool.

Place the beef roast in a large Ziplok bag.. Pour the cooled red wine vinegar mixture over the beef,and zip up all but a small hole in the top.  Squeeze out all the air so that the meat is completely surrounded by marinade and then close the top completely. Refrigerate for 3 days.  If you are neurotic you can flip the bag once per day but it is not necessary.

To cook the meat, begin by heating oil in a roasting pot. Add the bacon and cook until most of the fat has been rendered.

Remove the beef from the marinade. Pat the meat dry with a cloth or some paper towels. Season the meat with salt and pepper. Place the meat in the roasting pot and sear each side. Add vegetables to the pot with the meat and allow them to cook with the meat.

Pour the marinade through a strainer into a pot. Heat the marinade to a boil.  Add about 1 cup of the hot marinade to the meat along with the Lebkuchen. Cover the pot, reduce the heat to low, and cook the meat for 2 hours. About half way through the cooking, add the red wine.

Once the meat is finished cooking, remove the meat from the pot. Cover and keep warm. Pour the liquid and vegetables from the pot through a strainer into a bowl or pot. Return the liquid to the original pot. Mix in raisins and allow the sauce to cook down, until it is thicker. Season with salt, pepper, and optionally the apple sauce or red current jelly.

Slice the sauerbraten and serve with the sauce.