Accessories



 
 
 
The eyepiece box is made of oak, the partitions lift out and are made of poplar. The dimensions are 4 - 1/2' x 10 - 1/4" x 15 - 1/2".
Five eyepieces remain with the telescope, 4 of which are marked "500, 350, 185, 55" left to right in the picture. Presumably these are the powers of magnification. The "55" eyepiece is missing the eye lens. The rightmost eyepiece has no markings.
A close-up of the "185" showing the threads at the top of the eyepieces which allowed some of the accessories listed below to be attached.
This is possibley  a comet eyepiece. It looks much like the ones pictured in Alvan Clark & Sons Artists in Optics, 2nd ed., by Warner and Ariail, pg 244.
The same eyepiece showing the 2" inch lens.
The comet eyepiece threaded on the tailpiece.
Three filters that thread onto the eyepieces.
Two more filters that thread onto the eyepieces. These are variable density, from end to end, and slide over the eyepiece in a brass dovetail.
A star diagonal. This simply makes viewing easier for objects near the zenith by bending the light path 90 degrees to the eyepiece. The long end fits into the drawtube and the eyepiece in the shorter slotted tube. The light path is deviated by a prism whose surface must be very accurate to avoid distortion of the image.  About 10% of the light is lost due to transmission throught he reflective surface.

 
 

A solar diagonal. The solar diagonal, first made by Sir John Herschel has the same structure as the star diagonal except the right angle prism is replaced with  an elliptical prism of 10 degrees or less. The upper face is at 45 degrees to the axes of the two tubes and about 5% of the incident light and heat arrive at the eyepiece. This light can then be further attenuated by the filters pictured above.
 
 
 
 
 
 
 
 

The solar diagonal (top)  and the star diagonal. The solar diagonal tapers form the bottom (thicker) to the top (thinner). The light would be incident from the left.
 
 
 
 
 
 

Information on the diagonals was taken from The Telescope, by Louis Bell, 1922, pg 165- 166.

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