In 1769, Reverend Eleazar Wheelock founded Dartmouth, the ninth college in the nation.
In 1998, four daring, inspired Dartmouth undergraduates established the DUJS.
What else has happened?
I. Half a Century Ago…
The Wilder Laboratory witnessed the birth of New Hampshire’s first nuclear accelerator. This device, also known as the “atom smasher,” is an electric device used to study the nucleus of atoms. Scientists use it to accelerate particles such as electrons and protons that are smashed into the nucleus to study the result (Dartmouth’s accelerator smashed deuterium ions into deuterium targets) (1).
Professors Leonard M. Rieser, Jr. and William T. Doyle, shown in the accompanying picture from Rauner Special Collections Library spent nearly one year planning and constructing the accelerator for physics education at Dartmouth.
The accelerator could produce the total spectrum of atomic radiation, and thus, the experimenters needed to be careful. When using the device, precautions included X-ray dosimeters that measured the X-ray output and a radioactivity indicator that used a blinking light and a ticking sound to display the radioactivity output. A neutron counter took the central role of maintaining a safe environment by alerting scientists of neutron output.
To inhibit the radioactivity exposure, lead shielding surrounded the device, with an extra layer behind the control panel. Although the lead shielding provided adequate protection against X-rays, the emitted neutrons easily penetrated it. Hence, substances with high concentrations of hydrogen like oil, paraffin, or water were used to absorb the neutron emissions (2).
In contrast with the contemporary models, like the two-mile-long accelerator at Stanford, Dartmouth’s accelerator was one of only two in the country specifically designed for undergraduate courses. Even the first-year students had access to radioactive materials produced by this accelerator. At the same time, it certainly served as a magnificent research tool for graduate students and professors. Physicists at Dartmouth enjoyed having the impressive device for their use, and it remained as a symbol of Dartmouth’s commitment to undergraduate learning until the late 1960’s (3).
II. A Century Ago…
James Clark Maxwell (1831-79), who enlightened the world with his equations of electromagnetism, concluded that “in a medium in which waves are propagated there is a pressure normal to the waves and numerically equal to the energy in unit volume” (4). The significance of this conclusion was such that Italian physicist, Adolfo Bartoli, declared in 1876 that the validity of the second law of thermodynamics at least partially depended on the presence of such pressure. A few centuries before Bartoli’s statement, Johannes Kepler had also conjectured that the pressure of solar light accounted for the tail of comets blown away from the sun.
Many had attempted to experimentally prove the Maxwell’s equations without success. As Ralph Gibson explains it, such pressure only amounts to as much as that exerted by one sixty-thousandth of one sheet of Xerox paper (5). However, in 1901, E. F. Nichols and G. F. Hulls produced a convincing result in the Wilder Laboratory, which Nichols had helped build in 1900. This celebrated experiment took place in what is now Wilder 115 (the room that currently hosts classes such as Physics 15 and 16: Introductory Physics I and II, Honors Section). In 1901, they published their result in The Physical Review, one of the most distinguished journals in the field of physics, and their article was extensively read in Europe and in the United States (6).
In this section, the details of the experiment are only briefly treated; the full-length article may be found in The Physical Review as noted in the references. The process of measurement will be described using Figures 1 and 2, which come directly from their published article.
Nichols and Hull set up a lamp to provide the light coming from the left of the Figure 1, and the series of diaphragms and lenses (d1, d2, d3, L1 and L2) both intensified and focused the light into a beam. The slanted mirror, d5, was used to redirect a tiny bit of the beam to a small device above. This allowed them to keep track of the brightness of the light and consider possible irregularities in their final calculation. Also, a shutter (S2) was placed in front of the slanted piece of mirror, and it controlled the period of time the light was allowed to pass, providing the necessary Δt in the equation of impulse, ΔP=FΔt, to obtain the magnitude of force (F).
Following this path, the light would enter the Nichols radiometer, which was probably the best of its kind at the time. As shown in Figure 2, a fine quartz fiber was suspended in vacuum with a weight (m3) at its end. The light would shine on either silvered disc (G or S), causing the torsion wire to rotate slightly due to the pressure of light on the disc. The light was also allowed to shine on the other disc to take into account any asymmetries, while the experimenters guided magnets (M) around the upper body of the chamber to align the discs to be perfectly perpendicular to the projection of light.
How did they measure such an infinitesimal twist produced by the light? A tiny mirror, m1, was the key. In Figure 1, a telescope (T1) was placed in the distance on the side of the radiometer, and the telescope was positioned with a ruling engine, acting like a meter stick. When one looked through the telescope, the mirror would reflect the reading of the ruling engine, and Nichols and Hull could compare how much the torsion wire twisted by comparing initial and final values of the reading, thus obtaining the measurement of the pressure on the disc. And finally, the second telescope (T2) on the right determined the exact aim of the beam to ensure that it followed the designated path (4).
Although Nichols passed away a few years later during an American Physical Society meeting, their achievement left a lasting impact on the world of physics. Some even suspected that Einstein received his inspiration for his famous equation, E=mc2, from this very experiment (6).
III. A Century and a Half Ago…
The oldest scientific building on campus, Shattuck Observatory, was built in 1854. The story begins with a comment made by the Cambridge astronomer Royal George Airy in 1832: “I am not aware that there is any public observatory in America, though there are some able observers.” Before long, an “observatory movement” swept the country, resulting in over twenty new observatories, including the one we see on the hilltop east of the Green (3).
Shattuck Observatory represents Dartmouth’s first major scientific investment. Ira Young, professor of mathematics and natural philosophy, promoted the idea and made extensive travels and negotiations towards accomplishing this vision. The College Catalogue for 1849-50 proudly reads: “The lectures in astronomy are accompanied by celestial observations and instructions in the use of instruments. The splendid telescope obtained during the past year, ranking as the third in the United States, in magnitude and power, supplies important facilities for these purposes.” After the acquisition of the telescope, in 1852, he contacted a reputed Boston physician, George C. Shattuck, Dartmouth 1804, and his generous donations of $8,900 with the additional input by the trustees finally realized the dream of observatory.
Young was sent to Europe to purchase the apparatus and books, and Young’s brother, Ammi Young, was commissioned to design the building. Ammi Young was an architect of U.S. Treasury Department and had designed several other Dartmouth buildings and Boston’s Common House. Overall, the expenditure for the building cost $4,800 with total outlay of $10,000. In comparison, Young calculated that since the beginning, the College had only spent $2,300 for philosophical apparatuses.
At the time, the observatory included a two-story, domed rotunda with the equatorial telescope on the upper level and a library on the lower level, a meridian transit room to the east, a prime vertical transit room to the north, and a bedroom and additional observer’s room with a slit roof to the south. Revolving on six cannon balls, the 2800-pound dome allegedly could be turned with a force of only six pounds.
Charles Young, Ira’s son and a world-renowned scientist, along with John M. Poor and Edwin B. Frost actively used the observatory for research from about 1870 to 1890. Since then, it has served for teaching and public viewing. From the 1860s through the 1920s, students even lived in the building, working as custodians or weather observers. In 1865, one of the earliest boarders wrote to a friend:
I am now rooming at the Observatory. There is only one room in this building occupied by students & this is given out free to the best student in the Senior Class. The Sen. wanted to be absent three months & asked me to take his place which I accordingly did. I have the keys to every room in the building and have complete control of all the instruments…If you will make me a call I will let you look thro’ the Spy Glass all night if you want too” (3).
Today, one will notice a weather station adjacent to Shattuck. It is about a century old under continuous operation by the National Oceanic and Atmospheric Administration (NOAA). The departments of physics and environmental studies are currently pursuing plans to develop a system that will acquire, analyze and display weather data directly for Dartmouth’s use. Back when most of New Hampshire was open farmland, the observatory overlooked the town of Hanover and stood as a tangible symbol of science and learning. Although its heyday has now passed, and the vegetation returning to the hill limits its view, it still stands visible as a symbol of undergraduate learning to all who enter Dartmouth.
Acknowledgement
In this article, I have identified three underrepresented events that have momentously contributed to the scientific history of Dartmouth College. My intention is to inform the readers of these scientific legacies and help them appreciate the opportunity to pursue their studies here. I thank the following individuals for their help in gathering resources for this article: Richard Kremer, professor of history, whose publication, Study, Measure, Experiment: Dartmouth’s Allen King Collection of Scientific Instruments (2005) proved singularly informational on all the subjects, and Ralph Gibson, manager in the physics department, who shared much insight on the Pressure of Light Experiment.
References
1. L. Evans 2002. Glossary o to z. [Online].
(available at http://www.ecotao.com/holism/glosoz.htm). Accessed 2008 March 25.
2. F. Pemberton. New Hampshire Profiles. 22-24 (November 1955).
3. D. Pantalony, R. L. Kremer, F. J. Manasek. Study, Measure, Experiment: Stories of Scientific Instruments at Dartmouth College (Terra Nova Press, Norwich, Vermont, 2005).
4. E. L. Nichols, G. F. Hull. The Physical Review. XIII, 307-320 (1901).
5. Ralph Gibson, Personal Communication (2008).
6. P. Bruskiewich. Canadian Undergraduate Physics Journal. VI(Issue 2), 36-37 (2008).