In the summer of 1909 a 40-inch reflecting telescope make by Alvin
Clark and Sons was completed and put in operation at Lowell Observatory.
Although the actual glass disk was 42-inches in diameter, the mirror retaining
ring covered two inches of the glass. The telescope functioned as a 40-inch
from 1909 to 1925, at which time the mirror cell was enlarged to make the entire
42-inch mirror surface functional.

        Carl O. Lampland began employment at the Lowell Observatory in October
1902, a few months after graduating from Indiana University with a degree in
astronomy. He became the principal user of the 42-inch telescope from 1909 until
his death in 1951. He made over 10,000 direct photographs of nebulae, star
clusters, variable stars and planets at the Newtonian focus of the telescope.
Most of the photographs were made on 4x5 inch glass plates that covered a little
over one square degree of the sky. The scale of the plates is 36.7 arc seconds
per millimeter.

        To understand the validity and significance of the observing programs
persued by Lampland, the status of our knowledge of astronomy around 1910 must
be considered. At that time the distances to all types of nebulae and star
clusters were not known. In 1920, Harlow Shapley and H. D. Curtis participated
in a debate before the National Academy of Science as to whether spiral
nebulae are other galaxies or relatively small nearby objects. There were still
large discrepencies in the scale of the Milky Way in 1930, and reliable
distances were not known until about 1950.

        Lampland's life work with the 42-inch was to find answers to these
questions by annually observing the principal nebulae of the NGC (New General
Catalog of Nebulae and Star Clusters by Draper) and examining them with the
Zeiss blink comparator for changes and motions. He discovered several variable
stars, including novae in spirals and other nebulae; the remarkable appendage of
R Aquarii, and changes in the Crab Nebulae. He followed the growth of the
nebulosity attached to Nova Persei 1901 and left vaulable records of change in
nebulae, especially NGC 6729 Coronae Australis and NGC 2261 Monocerotis.
 
Henry Giclas, 2000