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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
McIntosh Milliammeter
One of these is in the Smithsonian labeled a “dosage meter.” It probably is part of a medical fake.
Hot Cathode X-ray Tube with Metal Collimator
According to Grant Gale, this belonged to Dr. Lemley, the first dentist in Grinnell to have x-rays.
