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Seth Thomas Clock 12
The Seth Thomas clocks, acquired by the college in December of 1888, represent the pinnacle of accuracy in timekeeping within their era. The clocks have very heavy cast-iron frames and gold-plated regulators. The polished brass tubes on either side of the clocks house the weights which maintain the rhythm and accuracy of the clock regulators. The college purchased the clocks after receiving the gift of an 8-inch Clark refractor, along with a chronograph, micrometer and a transit telescope. Grinnell offered practical astronomy classes for the first time in the 1888-89 academic year. Located in Goodnow Hall and used in the Goodnow observatory , the clocks were set respectively for solar and sidereal time. This clock is set for solar time.The second image shows the Goodnow Hall clock room in the early 1900's. The chronometer is on the table to the right.
The clocks, routinely maintained by Kens Clock Repair of Brooklyn, Iowa.. still keep excellent time and are on display in the Kistle Science Library in the Noyce Science Center.
Astatic Galvanometer with Glass Dome
A galvanometer is a device for detecting electric current. The galvanometer pointer deflection is from electric current passing through a coil immersed in a magnetic field from permanent magnets.
Galvanometer with Three Horseshoe Magnets
These two galvanometers each have three horseshoe magnets. The coil beside each magnet should be suspended vertically between the poles of the magnets.
Ivory Colliding Balls
Apparatus to demonstrate the conservation of momentum by the collision of balls having very hard surfaces is common, and ivory was a common material for the balls in the nineteenth century and early twentieth century. The use of ivory is not permitted now, and steel is the most common material for the balls. The balls on this apparatus are ivory.
Atwood's Machine
Atwood's machine is a device to observe the acceleration of a moving system acted upon by small forces. Two unequal masses are hung over a pulley by a light cord. The pulley turns with low friction, and the acceleration of the system of masses can be measured. The mass accelerated is the sum of the two masses on the string, and the force producing acceleration is the difference in the weights of those two masses. In this device, the pulley carrying the cord turns on roller bearings, like those designed by Atwood in the 17th century.
The second image shows the low-friction roller bearings
Student’s Oil Lamp
This lamp was used by Prof George L. Pierce while studying at Oberlin and given to the museum by Wayne and Clara Denny. Grinnell students used oil or gas lamps until the mid 1890’s.
