http://www.skyandtelescope.com.au 39We took both cell assemblies apart with great care,
marking the positions of all components carefully on
the lens edges and cells as we found them. Original
‘V’ marks remained on the edges of both the crown-
and flint-glass elements and lens cells, to show the
intended rotation of the elements with respect to each
other, but we reinstalled all components exactly as they
were when we took them apart — due to the unknown
source of the ‘V’ markings (was a better matching
of the lens elements done later?) and because the
objective performed perfectly as it was.
We cautiously cleaned the lens elements with
Alconox mixture, alcohol, distilled water, and wipes.
We used a spherometer to document the radius
of curvature of all lens surfaces. We also recorded
the thickness and diameter of each element and
the spacing between them, since no original Clark
drawings or specifications exist. All of the lens
elements are uncoated, and we left them that way for
historical authenticity.
One unexpected finding was a soft, silver-coloured
metal lining, most likely zinc, machined into both
lens cells at their contact areas with the glass.
Another surprise inside the 61-cm tube was a special
colour-correcting assembly that had been installed to
minimise chromatic aberration when the telescope
was used during the International Planetary Patrol
Program in the 19 6 0s.
Reassembling the mount and telescopes inside
the dome was far easier than their disassembly had
been. We polished and clear-coated all of the brass
pieces and most of the gearing, shafting, and other
metal components, thereby highlighting for all to
see the wonderful 1 89 6 engineering and machine
work that went into construction of this historic
masterpiece. In addition, we fully restored to working
condition one of the original mechanical clock drives
used to turn the telescope. This beautiful, historic
mechanism functions now as if it had just been
manufactured.
Lastly, we refurbished the observatory dome with
new, smoother-operating top shutters, extensive
internal and external wooden slat repair, and
weatherproofing and repainting.
The five people involved with the restoration
feel great accomplishment and deep appreciation
for the donors who made this project possible. This
storied astronomical facility now looks as if was built
yesterday. It should serve Lowell Observatory’s public
outreach program for another 100 years. ✦
Retired scientist Klaus Brasch is a docent at Lowell
Observatory. Ralph Nye is Director of Technical Services.
BEFORE AND AFTER The team performed fine-scale restoration work throughout.
Here, the hollow declination shaft (coming down from top) ends inside the endcap
at bottom; the counterweight shaft extends on below. Inside the declination shaft
are two coaxial rods that control the right-ascension slow motion and its clutch. They
end at the two flat gears seen above in the endcap, here stripped of its outer parts.
Other gears engage those to turn the right-ascension sector arm (the large V-shaped
part at top) for slow-motion control, and to lock and unlock it.RESTORATION TEAM From left: Peter Rosenthal (mechanical), Dave
Shuck (landscaping and dome), Glenn Hill (woodwork and painting), Ralph
Nye (project manager and mechanical), and Jeff Gehring (machinist and
mechanical). The project took 20 months.
LOWELL OBSERVATORY()