The Telescopes of Lowell Observatory.
A rough draft of an article that will likely appear in the Journal 
of the Antique Telescope Society, with excellent illustrations from the 
Lowell Archives, in 2001.
This is not a full description of these instruments.  Background information 
provided in the references cited in the bibliography was generally not 
repeated here.  Details given below were mainly provided by Henry Giclas & 
Brent Archinal, and are included in the event that they are not recorded 
elsewhere.

--1870, 2 1/4 inch tabletop model on cabriole legs, signed L. P. Casella, 
London, for Admiralty & Ordnance.  Given to Lowell when he was 15 years 
old by his mother and used on their roof in Brookline, Mass.

--1880, 6 inch Clark, with tripod & clock drive.  Lowell took this to Japan 
in 1892.  Douglas brought it to Arizona in 1894 to make seeing tests, but 
with the large tripod, it was too heavy to carry.  Currently the finder on 
the 24 inch refractor.

--1894, 12 inch Clark refractor, loaned by Agassiz of Harvard to Lowell for 
the 1894 Mars opposition, and donated in the mid-1910s.  Mounted with the 
18 inch Brashear camera; later used as a finder on 24 inch & the 42 inch.  
This telescope was built as a model for the Lick 36 inch and provided with 
a photographic corrector lens.

--1894, 18 inch Brashear photographic refractor, loaned by Allegheny 
observatory, mounted with the 12 inch Clark on an equatorial mount.

--1896, 24 inch Clark, 386 inch focal length, equatorial mount by the 
Clarks.  The objective was worked with glass tools instead of metal tools; 
and in 1905 was refigured by Carl Lundin.  Iris diaphragm in front of the 
objective to stop down the optics.  In 1901, Lowell purchased 
spectrographic equipment from Brashear, who supplied a photographic 
correcting lens for the 24 inch.  The 24 inch was Percival Lowell's 
primary instrument in his Mars investigations, and was used by V.M Slipher 
to measure the redshifts of galaxies & thus discover the expansion of the 
universe.

--1896, 4 inch Clark; original finder on the 24 inch.

--1896, another 4 inch Clark, used as a finder or as a personal telescope.

--1899, 12 inch reflector, Clark & Sons, 7.5 feet focal length.  This was a 
portable instrument, very little used, and the primary survives in its 
leather carrying case.

--1907, 5 inch Brashear, photographic doublet, 35 inch focal length; 
borrowed from Brashear for the first search for Planet X.

--1909, 42 inch reflector, Clark & Son.  4 foci, of 18.3 feet, 53 feet, 80 
feet, and 150 feet.  English polar axis mount.  A 40 inch telescope was 
ordered, but the blank was worked by Lundin to its full 42 inch diameter.  
The tube had been made to 40 inches, and not until 1925 was the tube 
rebuilt to allow 42 inches of aperture.  Lowell wanted to try a reflector 
on the planets.  Since there was no low expansion glass, he wanted to keep 
the mirror cool during the day, so he built the observatory floor 10 feet 
below ground level, which resulted in problems with turbulence.  This 
telescope was extensively used by Lampland to make over 10,000 plates of 
spiral nebulae & star clusters, and to discover supernovae.  Lampland 
pioneered infra-red radiometry, determining the temperature of Mars & 
Jupiter, using thermocouples made by W Koblenz of the Bureau of Standards.  
In 1948, the mirror became the first to be aluminized at Mt. Wilson.  
Circa 1952, Tombaugh ground & Lampland figured a convex aspherical 
secondary that directed the light to the lower end of the tube, at the 
side, but it was used very little, if at all.  Henry Giclas used the 
telescope in a solar variation project after 1956, and later for 
photoelectric photometry.  Harold Johnson and colleagues used the 42 inch 
extensively for photoelectric photometry of star clusters.  In 1956, the 
primary was refigured by Davidson Manufacturing of West Covina, who had 
been recommended by Don Hendrix, at a cost of $3600.  The mirror was 
delivered to Davidson April 4, 1956, and came back with a good figure.  
John Hall became director in 1958, and soon decided that the telescope 
would be better utilized as a Cassegrain.  In 1964, Tinsley was hired to 
core the primary by sandblasting through the 7 inch thick mirror.  At a 
depth of one inch into the glass, the mirror cracked into many pieces.  A 
smaller mirror was fitted into the tube, but very little use was made of 
it.  The tube now sits under a tarp, and will be placed in a display in 
2001.

--1909, 3 inch Clark (Lundin) refractor, a finder on the 42 inch.

--1914, Brashear 9 inch doublet, 46 inch focal length, used in the 
transneptunian planet search, borrowed from Sproul Observatory for 2 
years, and then returned.  About 1000 plates were exposed with this 
instrument, and 500 new asteroids were discovered.

--1926-7. 12 inch Petitdidier reflector, mounted on a polar axis mount made 
by Stanley Sykes, under the roll off roof at Lowell, where it remains.  
Later mounted at Peak Station, on Schultz Peak (11,500 feet).  The Peak 
Station was an attempt to get to better seeing, but it was actually more 
turbulent.  The San Francisco Peak scenic highway provided paved access, 
with a trail for the last 500 feet.  The Station was later used by 
Professor Shaw of Cornell, who brought a quartz spectrograph, and was 
trying to push UV exposures into shorter wavelengths, but he found he 
could get a similar result at Lowell with 20 minutes longer exposures.  
The toll road was later abandoned & the equipment brought down, and the 
telescope is now in storage.

--1927, 15 inch Petitdidier reflector, with 7 inch finder.  This telescope 
replaced the 12 inch reflector on the polar axis mount, and was then also 
sent up to the mountain station.  The mirror became one of the first 
experimental mirrors coated with aluminum by John Strong.  Aluminum with 
chromium overcoat was used, hoping to allow spectra at shorter wavelengths 
than other coatings.  Telescope is now in storage.

(James Edson made planetary cameras to go with the 12 & 15 inch reflectors.  
Edson was a photographic assistantt to E.C. Slipher, who made many plates 
with the 24 inch refractor.  Edson wanted to do some special work on the 
scattering of the atmosphere, and on the atomosphere of Mars, and needed 
an achromatic system for this.)

--1928-9, 13 inch Clark & Sons (Lundin) triplet astrograph, The Lawrence 
Lowell telescope.  Cooke triplet design, mount by Stanley Sykes.  Used in 
March 1930 to discover Pluto, and later in the Lowell proper motion survey 
and in asteroid surveys.

--1939, Schmidt Telescopic Camera, 8 inch / 12 inch, made by ATMs Harold and 
Charles Lower of San Diego, purchased by V. M. Slipher, and used by Clyde 
Tombaugh in a terrestrial & lunar satellite search during the 1950s.  Now 
in storage.

--1939, Schmidt camera, 24 inch / 30 inch, by Perkin Elmer, tested at Lowell 
for six months in 1939 & then sold to a college.

--1940s, Schmidt camera, 8 inch / 12 inch, by Indiana U. astronomer Wilbur 
A. Cogshall, used by Tombaugh in a terrestrial & lunar satellite search 
during the 1950s.

--1940s, experimental flat field Schmidt camera, made by Cogshall at Lowell 
in the machine shop, correcting plate figured to give sharp image at the 
edge of a 2 inch by 2 inch plate.  This camera was never put on a 
permanent mounting, and remained in its wood frame.  It is now in the 
'instrument morgue'.

--Schmidt optics, 24 inch / 30 inch, unmounted, Perkin-Elmer, never used, 
funding for large dome and mounting never provided.

--Schmidt Optics, 20 inch, unmounted, donated by French amateur, Julien 
Peridier, (while Peridier's protege Gerard de Vaucouleurs was at Lowell), 
never mounted, possibly made by Peridier.

--1953, 21 inch reflector, now mounted on polar axis under roll off roof, 
used for solar variation project, a dedicated photoelectric instrument.  
Possibly this mirror is by Mellish, he occasionally visited & made some 
optics for a Slipher spectrograph.

--1958, 24 inch Boller & Chivens Cassegrain, the Ronald Morgan telescope.  
Ronald was the son of Ben Morgan, who sold oil well equipment in Odessa, 
Texas, and wanted him to be an astronomer & bought this telescope for him.  
MIT & the Carnegie Institute were working on image tubes and needed a test 
telescope, so Morgan donated the 24 inch for this purpose.  It was used 
for photometric studies for about twenty years, and is now on display at 
visitors center.

--1961, 69 inch Perkins reflector moved from Ohio State, by Fecker / Warner 
& Swasey.  The primary was cast by the National Bureau of Standards, and 
was the largest single piece of glass ever cast (it probably retains this 
distinction to this day).  The observatory was completed in 1931, first 
owned by Ohio Weslyan, but shortly became jointly owned with Ohio State 
U., and circa 1980 ownership was transferred to Lowell.  In 1965, a new 72 
inch primary was installed, made by Don Loomis, f4.3 primary, overall 
f17.5.

--1963-4, Tinsley 20 inch triplet apochromatic refractor.  Originally owned 
by Ben Morgan at his summer home, he paid Tinsley about $250,000 for it & 
sued Tinsley over its performance.  Lowell purchased it circa 1963 for 
100,000 or less.  John Hall tested it and thought it was good enough.  It 
was returned to Tinsley for work once or twice; and taken to the U. of 
Arizona optical shop, where Don Loomis reworked & respaced it.  At Lowell, 
it was intended for lunar mapping, but it was not a successful lens, since 
it need to be stopped down to about 16 inches to provide a sharp image.  
Lowell had a contract with the Aero Chart & Information Center, St. Louis, 
producing lunar maps for the Air Force.  The project was headed by Mr. 
Canal (?), and Pat Bridges from St Louis worked at Lowell.  The telescope 
is shown in the  Dec. 1964 S & T, p368, in a Tinsley ad, which describes 
it as 'ordered for lunar mapping'.  The objective is now on display and 
the dome & part of the mounting are still in use.

--1965 (circa), 31 inch, f5 reflector on Anderson Mesa, from USGS, who used 
it in a mapping of the moon project, and then sold it to Lowell, which 
refurbished it for use by undergraduates & the public.

--1966, 42 inch Ritchey Chretien reflector, f8 or f16, by Astro Mechanics 
Corp. of Austin, Texas.  The John Hall telescope, it is installed on 
Anderson Mesa, and used with CCDs every clear night.

--1984, 18 inch astrograph, made by Perkin Elmer in the late 1950s.  A James 
Baker design, f8, 5 element aerial camera lens.  Mounted on the pier used 
for the Tinsley 20 inch, where it remains, although it was last used a few 
years ago for occultations and to obtain accurate positions of faint 
stars.

--1995, Boller & Chivens 16 inch McAllister telescope, f3 primary, f18 
system, built 1963, used for public viewing, originally in Dearborn 
Observatory in Michigan, donated by Northwestern University & moved in 
summer 1995.

--1997, LONEOS (Lowell Observatory Near Earth Object Search) Schmidt camera, 
22 inch / 24 inch, used to find earth crossing asteroids & comets.  
Originally a 16 inch / 24 inch f2.7 Schmidt, with an 8 inch / 12.5 inch 
f1.5 Schmidt camera mounted with it on a fork mount, all by Fecker.  It 
was made in 1940 for M.R. Shottland, a West Virginia amateur, who also 
purchased a 32 inch Fecker Cassegrain; both of which were donated to Ohio 
State & Ohio Weslyan in the late 1950s.  The 32 inch was installed in the 
dome of the 69 inch at Anderson Mesa, and the Schmidt in its own dome, 
where it saw little use, despite its high quality and very precise clock 
drive.  (The 8 / 12.5 might still be in Ohio.)  In the early 1990s, the 16 
inch aperture was increased to 22 inches, and the drive, mount and upper 
tube were reworked in the shop at Lowell, for use by Gene Shoemaker, and 
later as a dedicated LONEOS instrument.

--The Navy Prototype Optical Interferometer.  Three 50 cm siderostats that 
feed light into 250 meter vacuum tubes, towards beam combiners and 
telescopes, with laser interferometers to measure path lengths.

References for more information:
Giclas, Henry. The 13 inch Pluto Discovery Telescope.  Flagstaff: Lowell, 
1997.
Giclas, Henry. History of the 13-Inch Photographic Telescope and Its Use 
Since the Discovery of Pluto. Icarus 44 (1980) 7-11.
Hoag, Arthur. An Astrometric Lens Caper. Sky & Telescope 69:3 (March 1985) 
214-5.
Putnam, William Lowell. The Explorers of Mars Hill, a Centennial History of 
Lowell Observatory.  West Kennebunk: Phoenix Publishing, 1994.
Schindler, Kevin. 100 Years of Good Seeing, the History of the 24 inch Clark 
Telescope.  Flagstaff: Lowell, 1996, 1998.
Slipher, V.M. The Lowell Observatory. Publications of the Astronomical 
Society of the Pacific 39 (1927) 143-154.


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