Bob Wilhelm’s Q&A

Answer
Born on September 8, 1818, in what is known today as the Dixon-Jackson House, J.G. Jackson studied at the Westtown Boarding School beginning at age 14. In his 20s, he began teaching science and astronomy at Westtown. Jackson became a surveyor’s apprentice when he was 21, mastering the profession while working for the government in Ohio. By age 30 (1848) Jackson was supervising the family’s Hockessin saw mill operation, doing surveying within New Castle County, supervising the daily operations of the limestone and marble quarries on the family’s property, and overseeing construction of a new home for his family northeast of Valley and Southwood roads.

John G. Jackson became a notary public for New Castle County in 1857 at age 39. In November 1864, Jackson successfully won the election to become a State Representative for New Castle County in the 73rd Delaware General Assembly for two years (January 3, 1865 to January 1, 1867). Jackson served as Chief Engineer for the Wilmington & Western Rail Road’s construction between 1870 and 1872, and its route remains a testament to his skills as a surveyor and engineer. In 1880, at age 62, Jackson began to embrace retirement by selling the quarry business. Jackson continued his surveying activities in later years as he applied for a patent related to surveying in June 1888. Jackson was awarded Patent 392,124 on October 30, 1888, for a ‘Spirit-Level’.

Jackson was an avid astronomer, and in 1837 he worked out the calculations for the next transit of Venus (a transit is when the orbital planes of Earth and Venus are aligned such that from the daylight side of Earth one may observe Venus as a black dot moving across the sun). When Jackson made the initial calculations, only two individuals had ever observed Venus transit the sun (in 1639). One must remember that humans did not know the precise orbits (elliptical and not circular) of Venus and the Earth or their mean distances from the sun.

Jackson used his telescope, observational skills, and math knowledge to calculate current positions and then to reliably predict the future orbits of the Earth and Venus circling the sun. Adding to the complexity is the fact that the orbital planes of the two planets are different (3.8 degrees), the frequency of Earth-Venus-Sun alignment occurrence differs (105.5 years, 8 years, 121.5 years, 8 years before repeating), and the calculations are done with only a pencil and paper by kerosene lamps!

The 1874 Venus transit was not visible in North America (it was visible in eastern China, Australia, Japan, Indonesia). Jackson was rewarded for his efforts on December 6, 1882, when he was able to document, along with other noted astronomers across North America, the transit of Venus as he and others had predicted 37 years earlier! Jackson’s work is documented in multiple astronomy periodicals of the time, and his involvement is noted in Congressional records. Jackson owned a 6-inch reflecting telescope that he most likely made himself. This would have been a large telescope for a private individual as the best observatories around the world had telescopes of the size of Mt. Cuba Observatory’s 24-inch reflector in the 1880s.

J.G. Jackson is also documented as having observed “clouds” on the moon on multiple occasions. Galileo Galilei’s improvements to the telescope in the early 1600s allowed better viewing of the moon. As far back as February 1672, a “nebulous appearance” had been reported in the Mare Crisium region of the moon by Giovanni Domenico Cassini. From Cassini’s first reporting until Jackson’s time, dozens of reported sightings had occurred, with some reporting a purple color to the cloud or fog.

As part of America’s preparations for going to the moon, in 1968 NASA released a Chronological Catalog of Reported Lunar Events documenting 580 observances over nearly 300 years of cloud-like phenomena on the moon. By the early 1900s, it was well accepted that the moon did not have an atmosphere. Continued study of the moon concludes that the “clouds,” bright flashes, and other lunar phenomena are more than likely the result of out-gassing from the moon’s crust, impacts of space debris with the surface, or similar causes. Only since the Apollo flights of the 1970s have we learned the moon does have what can be considered an atmosphere (ten trillion times thinner than Earth composed of atoms of sodium, potassium, helium, argon, ammonia, methane, and carbon dioxide).

An alternate to silica-based glass is acrylic glass. Technically known as Poly-Methyl-MethAcrylate (PMMA), we commonly refer to the material generically as plexiglass. Developed by Rohn & Haas Company commercially in 1933, their Plexiglas product was trademarked in Germany as the world’s first clear acrylic material. Imperial Chemical Industries Ltd. (ICI) registered the product in the UK at about the same time as “Perspex.” In the U.S., E.I. du Pont trademarked Lucite as their acrylic glass product offering. Other companies have trademarked names such as R-Cast, Optix, and Cyrolite.

In 1939, for the World’s Fair, the car below was featured having its exterior body panels fabricated from Rohm & Haas Plexiglas. It was advertised as the first “transparent car” in America. Who was the manufacturer of the automobile pictured, and which major automotive manufacturer showcased the vehicle during the fair?

Answer

Often called the PlexiPontiac, or the Pontiac Ghost Car, it is a 1939 Pontiac Deluxe Six. It was built as a collaboration between General Motors, Pontiac, and Rohm & Haas for the GM “Futurama” exhibit and was part of the “Highways & Horizons” display. Built on a 120-inch wheelbase, Pontiac four-door Touring Sedan framework and chassis, the metal structural components were copper plated while the car’s accent hardware was chrome plated. Black rubber moldings were changed to white rubber as were the tires, for contrast. The engine used was a 222.7-cubic-inch L-head six-cylinder that generated 85 brake horsepower for the three-speed manual transmission.

Costing $25,000 to build, the odometer displays only about 100 miles of driving! After being one of the must-see highlights at the World’s Fair, the car toured the U.S. before becoming a feature attraction at the Smithsonian Institute for a number of years. Upon leaving the Smithsonian in 1947, it was displayed in several Pennsylvania dealerships. It was purchased in the early 1970s by a private owner, who had it restored. Sold to another private owner in the late 1970s, it was again sold to a private owner in the 1980s. In July 2011, it was auctioned by RM Auctions for $308,000.

A second car was built after the Ghost Pontiac on the Pontiac Torpedo Eight chassis for the Golden Gate Exposition. It too toured the country, but its status is unknown.

The rare item pictured has been awarded a National Register of Historic Places listing. It is located on the border between Delaware and Maryland in Delmar but originally found use in northern Delaware as well as 25 miles away in Hurlock, Maryland. After serving some of its life in Cape Charles, Virginia, it has been returned to Delaware. What is the pictured item called, and how was it used?

Answer
The item pictured is a railroad Highball Signal dating from the earliest railroads that operated on the DelMarVa Peninsula. From the Delmar Highball Signal’s National Register Listing;

The term highball, meaning a fast train, or permission for a train to proceed at full speed, derives from this type of signal. A highball signal was a white sphere mounted on a pole next to the railroad tracks. If the track was clear ahead, the signal attendant would raise the ball to the top of the pole by means of a pulley. If the track was not clear, he would lower the ball so that it would not be visible to the engineer of an oncoming train; hence, the term highball came to be synonymous with a clear right-of-way. Positioned as shown in the image, at the midpoint of the pole, the signal indicated the engineer was to proceed ahead slowly with caution.

Highball signals were frequently mounted near stations or at section boundaries. The design of highball signals varied among the railroads; some were equipped with a black ball that would replace the white one when the track was not clear. Some signals, like the one at Delmar, were provided with a box into which the ball was lowered when the track was not clear. Some railroads constructed the ball with glass windows such that it included a kerosene font and burner and could be lit at night for better visibility. Other types of signal, notably the semaphore and the three-light electrical signal, eventually replaced the highball. The highball at Delmar is a steel sphere mounted on a wooden post, which is raised and lowered by of a chain hoist. It is no longer used to direct railroad traffic, but is maintained as a public exhibition in a park near the railroad.

The highball signal at Delmar is one of the last survivors of a type of traffic control that was in use before the advent of modern semaphore signals. The origin of the highball is unknown, but it probably was invented during the railroad expansion period of the 1840’s. As a signal, it is quite primitive, since it can convey only one piece of information: whether the track is clear or not. Modern signaling devices can transmit a variety of data to the engineer of an oncoming train. The last highball signal on a class 1 railroad in America was in operation at the interchange point between the Pennsylvania and Reading railroads near Wilmington Delaware, a few years ago; the highball was used at that point because the electronic control systems of the two railroads ended short of the interchange track and manual signaling was necessary.

The Delmar highball signal was originally in service at New Castle, Delaware, and then at Hurlock, Maryland. It was displayed for a time at Cape Charles, Virginia, and then was moved to Delmar, Delaware for display during the town’s centennial in 1959. It is maintained as a permanent exhibit by the town of Delmar, Delaware.

The books of the late 1800s and the movies of the mid-1900s have tended to embellish the typical train robbery of the the late 1800s. Riding alongside a moving train and jumping aboard was a dangerous proposition. It was far easier for robbers to buy a ticket and board as a paying passenger to gain access to a train to be robbed. A few robbers could take over a train and bring it to a stop at a prearranged location where other gang members could board and not only relieve passengers of their gold jewelry and other valuables but dynamite safes in baggage or box cars.