Amateur Astronomers Association of Princeton

by Michael Wright

The Business End of the Vassar Telescope Credit: Mr T in DC (CC license)

Last month I wrote about Maria Mitchell’s connection to the Vassar Telescope, which is on display at the National Museum of American History of the Smithsonian.  This second installment covers the telescope itself and its maker, Henry Fitz.

Vassar College purchased “an Achromatic telescope objective object glass 12 inches aperture, 12 3/8 inches in diameter” from Henry Fitz for $2500 according to the April 6, 1863 minutes of the Trustees.  Also, they record that there were only four larger glasses in the US at the time.  In September, 1863, the Trustees contracted with Henry Fitz “to mount & furnish said object glass in all respects conformable to the annexed specifications for the sum of two thousand & three hundred dollars.”  The specifications were as follows:

Style the general style of mounting shall be the Fraunhofer Equatorial.

Iron The Bolster, Saddle, the declination box, the adjustable weights, the two axes & the counterpoise may be of iron.  The counterpoise is to be globular & ornamental.

Circles The circles shall be the best-variety of brass with inlaid silver plate for the division marks.  The Declination circle shall be twenty inches in diameter & accurately divided to read to thirty seconds of arc; & the Right Ascension circle shall be eighteen inches in diameter & divided to read to four seconds of time.  Both circles shall be furnished with vernier & reading glasses.

Tube The tube of the Telescope shall be made of mahogany with rosewood finish & well polished.

The finder scope was to be “of the best quality & whose object-glass shall be three inches in diameter set in a tube of like material and finish as the main tube.”  Eyepieces were to be one set of eight “positive” (Ramsden) eyepieces and one set of nine “negative” (Huygens) eyepieces of powers ranging from “50 to 1500” for direct observation.  (150x?).  The balance rods, which I believe are the two long rods with brass balls at one end, were required to be “firm & of tasteful pattern with brass adjustable weights.  The rods may be of wood but must be seemly and neatly attached with brass mountings.”  In addition, Henry Fitz was to provide a “prismatic mirror for diagonal views”, a filar micrometer, a ring micrometer, a Bond’s and Dennision’s spring governor and a spectroscope.  As one can tell from the photo above, this was a handsome instrument, but how did the optics perform?  Perhaps not so well.  In 1868 shortly after installation, Alvan Clark & Sons reground the lens to such a degree that they considered it their own according to Deborah Jean Warner in Alvan Clark and Sons Artists in Optics.

So who was Henry Fitz?  Fitz was a contemporary of better known telescope maker Alvan Clark.  Born in 1808 in Newburyport, Massachusetts, Henry Fitz became a locksmith and well-known amateur astronomer by the 1830s.  In 1839, he traveled to Europe to learn about astronomical and photographic optics.  While there, he established connections with French glass-suppliers, learned the new Daguerreotype photographic process and learned lens making from English and German opticians. Upon returning to the US, he patented an improved Daguerreotype camera and opened a successful optical business in Baltimore, which allowed him to experiment with optics. In January 1845, he succeeded in producing a high-quality achromatic lens.  Later in the year, he made a six-inch refractor, which received a gold-medal at the American Institute Fair.  With earnings from public stargazing with the telescope, Fitz launched into making telescopes full time.

Fitz’ innovative lens-grinding techniques allowed him to produce large, high-quality objectives using lower-quality, cheaper glass so American’s did not have to rely on expensive imports from Europe.  This contributed to the proliferation of American observatories during the mid-19^th century.  His important telescopes are as follows:

• 1848,  a six-inch refractor for Lt. James Gillis for his Chile expedition – The objective was tested against and judged equal to a high-quality German import demonstrating that Fitz could produce high-quality objectives.
• 1849, a 5.6-inch telescope for Erskine College, which was his first observatory instrument
• 1849 or 1850, a 6 3/8-inch refractor for Robert Van Arsdale of Newark, New Jersey
• 1851, another 6 3/8-inch refractor for South Carolina College
• 1852, an eight-inch refractor for Haverford College
• 1856,  a 9 ¾-inch refractor for West Point Academy – This $5000 telescope was 14 feet long and came with 13 eyepieces.
• 1857, 12 ¼-inch for the University of Michigan in Ann Arbor – At the time, this was the largest American-made telescope and the third largest refractor in  the world.  It is probably the most important surviving Fitz telescope because it has the largest objective untouched by later refiguring.  It is still on its limestone pedestal and in working condition after 154 years.
• 1861, a 13-inch for the Allegheny Observatory in Pittsburgh.  Eleven years later, the lens was stolen and held for ransom.  (Even criminals new the value of a big scope back then!)
• 1861, Fitz delivered his largest and most innovative telescope, a 16-inch refractor with a two-element corrector lens midway down the tube, to William Vanduzee of Buffalo, New York.  This was the largest telescope in the world at the time.
• 1863, a 13-inch refractor for Dudley Observatory in Albany, N.Y.

At the time of his death in 1863, Henry Fitz had plans for a 24-inch scope and was working with Lewis Rutherfurd on a telescope for astrophotography.  The later scope was completed one year later by Henry’s 16-year old son, Harry, who carried on the business for another 20 years.  Henry Fitz’ techniques were state-of-the-art for his time.  As testing procedures rapidly improved, many of his objectives were refigured by other artisans, so few Fitz objectives remain in their original condition.

This brief biography of Henry Fitz was distilled from the Journal of the Antique Telescope Society, Volume 6, Summer 1994, revised 1995, 2000.  The journal contains more detailed information on Fitz, his telescopes and his lens-grinding techniques. Also, NMAH has an interesting podcast about his workshop, which was donated intact to the museum in the 1950s.

The next time you are in Washington, DC be sure to visit the Vassar Telescope at the entrance to the science and technology wing of the National Museum of American History and enjoy this beautiful icon of 19^th century American astronomy.