The Cooke/Clarke Telescope of the
Maria Mitchell Association
 

 

After nearly a centiry of service, the historical Cooke triplet astrograph of the Maria Mitchell Association is no longer being used for research. Nevertheless, it is an important historical telescope. The Maria Mitchell Association is considering how to balance the needs of the Observatory for better research instrumentation against the responsibility to maintain the historical integrity of this instrument.

   Therefore, we at the Nantucket Maria Mitchell Association (MMA), have decided to look for a trade or purchase arrangement whereby our 1913 telescope can find a new home with a responsible owner and we can end up with a modern research instrument.
From 1913 to 1996, more than 8,000 plates were taken with this telescope. We have digitized these plates ,and copies are available upon request.
  Anyone interested in acquiring this historic telescope should contact Dr. Peter Boyce to discuss possible arrangements.

 

The Telescope

The Maria Mitchell Association is seeking to upgrade the research capability at itsVestal Street Observatory, and now offers to trade the historic 7.5-inch photographic telescope for a modern, computer-controlled, research-grade mount capable of carrying a telescope in the 20-24 inch size range.

The historic telescope seen on the left dates from 1913 and comprises a Cooke triplet lens in a mount made by Alvan Clarke and Sons. Although the drive was changed to electric motor at some time in the past, the original clockwork drive mechanism was preserved and can be reinstalled. The telescope was ordered in 1912 and first put into service on August 13, 1913. There is a long 5-inch guide telescope on the far side of the telescope.

The telescope is in excellent working order

The photographic variable star monitoring program ceased in 1995, due in part to the inability to obtain astronomical glass plates, and because the research program of the Observatory was moving in new directions. A removable holder for a Meade CCD camera was fabricated which can be mounted in place of the plateholder. No changes were made to the original photographic plateholder. The CCD camera mounting mechanism is included as part of the telescope package.

History

The telescope mount dates from 1912 (Alvan Clark - Cambridge) and the
T. Cooke triplet lens also dates from then. According to the stamping on the lens cell, it was corrected and remounted in 1941 by J.W. Fecker of Pittsburgh, PA.

The Telescope Drive

The original clockwork drive was removed and replaced by an electric motor drive at some time during the telescope's history. We are obtaining more information about when this was done. The original clockwork mechanism is in excellent shape and lacks only the weight. The electric motor drive was installed carefully, with very little alteration to the original pier, so it appears that the clockwork mechanism could be reinstalled easily.

 
The clockwork drive mechanism. The drive shaft to the telescope is attached through the black supports in the lower center of the picture. Another view of the clockwork drive mechanism. The mechanics are in excellent shape. View of the drive train showing the linkage between the motor and the RA worm gear. The electric motor is visible through the window in the pier.  
 

Some Detailed Views

  

The worm gear in the left veiw is in good working order. Note the polar altitude adjustment.

On the right is the present electric drive which appears to be easily removable, aparently leaving the original drive mounting points intact. The clockwork mechanism can probably be reinstalled with little or no further modfication needed to the mounting points. The original mounting screws are, of course, no longer available.

The package

The view to the right shows the photographic telescope (grey tube) and the 5-inch guide telescope in its brass tube (orange). The Cooke triplet lens holder is the bronze portion mounted at the front end of the grey telescope tube. The metal extension with the electrician's tape on it is a completely removable dewcap.

The lens is 7.5 inches in diameter with an e.f.l. of 33.75 inches. The plateholder uses 8 x 10 inch glass plates. The optics are quite good, although the images are somewhat poorer at the edges of the field.

The guide telescope currently has mounted in it the lens from Maria Mitchell's own telescope -- the one which was made by Alvan Clark and presented to her by "The Women of America" in 1859. This lens was mounted in the guide telescope tube in 1913, but is not part of the package. The MMA will keep this lens and have it remounted in the original mahogany tube to become part of its exhibits. The guide telescope tube is part of the package.

In summary, the package being offered consists of::

  • the steel pier and mount, including the electric drive
  • the telescope tube
  • the Cooke triplet lens
  • the guide telescope tube
  • the original clockwork drive
  • plateholders

In return, we are seeking::

  • a research grade mount to hold a telescope of 20-24 inch diameter
  • a computer control system
  • removal of present telescope and installation of the new telescope mount and control system
  • other services or funding as agreed upon

Anyone interested in discussing aquisition of this instrument should contact Dr. Peter Boyce to discuss further details and possibilities. The MMA would prefer that the telescope be made available to the public. We would be pleased if it continued to be a working telescope. Because it is a historically significant instrument, we expect that the telescope would continue to be identified as the telescope that came from the Maria Mitchell Observatory, and that the history of the telescope be kept with it. Please email us to discuss your interest.

Last changed 1/10/04 (Top of page)
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Page maintained by Peter Boyce  

email: pboyce@aas.org
home phone: 508-228-9062