Photograph of Dr. Millikan using instrument to study the cosmic rays, [s.d.]. At center, a seated man is visible hunching forward to the right. The man is wearing a large lab coat with a folded collar extending down to his knees. The man's thin hair is neatly parted and combed to the side. The man is looking down into the eyepiece of a large instrument. The cylindrical eyepiece is connected to a large drum base. At the top of the drum, a spherical dome can be seen extending to the right. Wires can also be seen running along the side of the drum. Description on the photo sleeve reads: "Dr. Millikan with Instrument Studying the Cosmic Ray, Copied December 1930".