Lind Electroscope (ca. 1925)

Lind electroscope
Lind electroscope diagram

This electroscope was developed specifically for the measurement of radioactive samples, and in particular, radium and its decay product, radon. The key feature of the Lind electroscope is the fact that it employs separate interchangeable chambers for the samples. 

The chamber employed for radon measurements (example on right side of above photo) has two stopcocks that can be used to seal off the chamber. The central electrode, a vertical brass cylinder ½ inch in diameter, terminates in a small metal ball on top of the chamber. When the chamber is connected to the electroscope, this ball comes into contact with a spring at the bottom of a vertical rod in the electroscope from which an aluminum leaf (ca. 5 mm wide and 4.5 cm long) is suspended. The rod and leaf are charged via a moveable charging rod controlled by a knob on the side of the electroscope. A vertical flat plate, controlled from the opposite side of the electroscope, can be positioned beside the leaf to protect it when the electroscope is moved.

Lind electroscope

The movement of the leaf is viewed through a microscope mounted on the side of the electroscope.

The chamber for use with solid samples (on left side of first photo) employs a hinged door through which the sample can be introduced or removed.

My best guess would be that this electroscope was developed by Sam Lind sometime around 1920.

This example was employed in the Hale Building at the University of Colorado. The property cards are dated 4-6-26.

Sam Lind portrait

Sam Lind

Born in Tennessee, Lind first worked with radioactivity at the laboratories of Marie Curie and Stefan Meyer in 1910 and 1911 respectively. From there, he returned to the United States and went to work with the Bureau of Mines in Denver, the University of Minnesota, and finally, Oak Ridge National Laboratory. He is generally credited with being one of the first, if not the first, radiochemist. Lind died while trout fishing in the Clinch River in 1965. He drowned before he could wade to shore following the release of water from an upstream dam. Phil Rudolph, Lind's longtime coworker, said that the day before Lind died, Lind had commented that when his death came, he wanted it to be while fishing.

Donated by Albert Bartlett.