Enfilade

On a day when many of us are looking to the skies . . . Press release from Bath’s Herschel Museum of Astronomy:

James Short, Gregorian reflector telescope, 1738–68 (Collection of Richard Blythe, on loan to the Herschel Museum of Astronomy).

The Herschel Museum of Astronomy recently revealed a new display: a Gregorian Reflector telescope created by James Short, the preeminent telescope maker of the 18th century. The brass telescope, on long-term loan to the museum from Richard N. Blythe of Shropshire, was created between 1738 and 1768. It has a focal length of 18 inches and sits on an equatorial mount. Similar telescopes made by Short were used to observe the transit of Venus in 1761 and 1769.

Gregorian Reflector telescopes are constructed with two concave mirrors. The primary mirror collects incoming light and brings it to a focal point. This focused light is then reflected off the secondary mirror, after which the light passes through a central aperture within the primary mirror. Ultimately, the light emerges from the bottom of the instrument, facilitating observation through the eyepiece.

In his 30-year career, Short made at least 1300 telescopes. Considered the finest available, they were sought after by observatories and customers all over the world. Short had no assistant, and when he died in 1768 his method of polishing mirrors was lost. Separately, William Herschel started experimenting with making telescopes in 1773 and went on to produce telescopes of even greater quality than those by Short.

Herschel Museum of Astronomy, 19 New King Street, Bath (Photo by Nick Veitch, Wikimedia Commons, August 2005). Brother and sister, William and Caroline Herschel moved into what was then a new town house in 1777, just a few years before William discovered Uranus (in March 1781). The Herschel museum was established in 1981.

Patrizia Ribul, Director of Museums for Bath Preservation Trust says: “The story of the Herschel siblings William and Caroline is very special, and our acquisitions policy is focused on objects that either belonged to them, or that add important context from the time. The James Short telescope provides visitors with an excellent example of the type of telescope that would have been known to William Herschel. The fact that William, with Caroline’s assistance, went on to create telescopes superior even to this excellent example by James Short, really underlines his expertise and dedication in the field of astronomy.”

The James Short telescope is the latest in a line of exciting long-term loans and acquisitions at the museum, including Caroline’s visitor book, a full-sized replica of William’s seven-foot reflecting telescope, and Caroline’s original memoir manuscript.

The Herschel Museum of Astronomy is dedicated to the achievements of the Herschels: distinguished astronomers and talented musicians. It was from this house that William discovered Uranus in 1781.