Instruments that used a spinning coil to generate an electric current by means of the earth's magnetic field, and to measure the angle of "dip" of that field, were developed soon after the discovery of electomagnetic induction, but were used for a variety of purposes and took on a multiplicity of forms. In general, the early ones were didactic and non-quantitative; later came more elaborate designs that could yield precise numerical data for geomagnetic research.
Roger E. Sherman
B.A., Yale University, 1979
History of physics, especially experimentation, experimental apparatus, and instruments.
- Recreation of Joseph Henry's early experiments with electromagnets, for the Hands On Science Center
- Study of early induction coil of Charles Page, in support of project investigating similar instrument in Dartmouth College collection
- Assistance in running weekly NMAH colloquium program.
- Service as Radiation Safety Coordinator for NMAH.
- Collaboration in development of exhibition marking 25th anniversary of the Three-Mile Island nuclear reactor accident
- Trip to government laboratories in Oak Ridge, Tennessee, to identify Manhattan Project artifacts for possible collection
- Assistance with selection and interpretation of NMAH objects for 1848 exhibition at Cooper-Hewitt Museum.
- Investigation and identification of Weber earth inductor; Henry motor and current interruptor; Nichols and Hull pressure-of-light apparatus.
- Service on NMAH science exhibition proposal committee.
- Exhibition Striving for Standards commemorating 100th anniversary of National Institute of Standards and Technology
- Designed sealed containers for storage of fragile radioactive specimens.
- 2003 Peer Recognition Award for innovation and creativity
- 1998 cash award for processing of Tucek carbon-14 dating apparatus.
Henry constructed in 1830 the strongest electromagnet in the world; the principles he discovered in the process led him on to devise an electric motor. His spectacular magnets launched his scientific career, but in the case of his motor, his reluctance to be involved in non-scientific applications of his discoveries battled in his psyche with his need for credit and recognition, leading to a curious ambivalence.
Before the development and widespread availability of convenient light sources operated by electricity, the sun was the best illuminant for optical experiments that required strong light. To provide a stationary beam of sunlight,
physicists in the eighteenth and nineteenth centuries invented a number of instruments that used clockwork mechanisms to move a mirror to compensate for the sun's apparent movement. The ingenuity and variety of principles embodied in these "heliostats" reveal how important the problem was considered to be.
An extensive and rich collection of demonstration apparatus, stage decorations, posters, handbills, and letters, acquired by NMAH, yields a detailed picture of the life and struggles of a minimally educated, but enthusiastic and hard-working, showman who traveled about the rural villages of upstate New York in the 1840s and 1850s, lecturing on electricity, astronomy, and other subjects. The collection and what it reveals about Came is important because very little is known about such rural lecturers and what they told and showed to their audiences.
A broadside dated Providence, R.I., 1793 shows that Greenwood was giving a lecture on electricity, with demonstrations, that followed a tradition for such lectures already half a century old in America at that time.
The American electrical scientist and inventor Charles G. Page and the Boston maker of didactic electromagnetic instruments Daniel Davis had a close working relationship for several years, beginning apparently in 1838. Davis made, sold, and described in his catalogues Page's inventions, often before Page himself published them in the scientific press, while Page benefited from Davis's mechanical skill and workshop facilities in the construction and testing of his new instruments.