The Hensoldt Protami
was introduced in 1925 in the form of the present
example. Before 1935, an improved model was
introduced. The outer case and the microscope are
constructed of metal and brass with painted and
chrome surface finishes. The cased microscope
measures 6 1/4 inches tall, while the microscope is
9 1/2 inches tall with both drawtubes fully
extended as shown in the photos. The microscope is
focused by means the knurled collar located midway
on the body of the microscope. The triple turret
objective holder is equipped with objectives marked
T, M, and P (n.a 1.30, 1/12). The latter is an oil
immersion objective while the T objective is
divisible for obtaining the lowest power settings.
These objectives, along with various setting of the
drawtubes, are designed to provide magnifications
in the range 40-1200. The two drawtubes each have
three calibrations for use with each objective.
Additionally, the microscope is equipped with an
Abbe condenser with iris diaphragm, flip-up stage
clip, flat and concave mirrors on an adjustable
arm. The stage can be flipped out of the optical
path for easier access. The base can be screwed off
revealing a compartment that holds a corked glass
vial for immersion oil.
This microscope was
the working field instrument of Edson Snow Pettis
(1887-1953). Originally from Somerset and Taunton
Massachusetts, he was trained as a mining engineer
and metallurgist by serving an apprenticeship with
Abbot A. Hanks in San Francisco, in 1903. This can
be ascertained by reading his first employment contract. He
spent remainder of his career operating in the gold
mines of the western United States, Canada, and
South America. Undoubtedly, he found his Protami
microscope a useful instrument for examining the
output from these mines in the field.