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This type of heliostat, along with the secondary directional mirror on the left, was sold by the John A. Brashear Company around 1910 for $110. The clock mechanism was manufactured by the Seth Thomas Company. The nameplate is lacking on this instrument, and it is not clear if the Brashear Company made this heliostat or was acting as a dealer. |
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Larry Webster, of the Mt. Wilson Observatory, provided information regarding the maker and also connected the secondary mirror with the main instrument. Mr Webster has a similar heleiostat in his collection that is signed "John A. Brashear Co. Ltd. Allegheny PA USA". |
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The cover plate of the heliostat with the key used to wind the clock on one of the two shafts used for that purpose. The "drop" shaped door in the left of the picture covers the access to a smll lever that controls the speed of the clock movement. |
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The adjustment at the base is used to set the polar axis for the observers latitude and is adjustable from 0 - 60 degrees. |
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The mirror cells for both pieces are similarly constructed. The mirror is held at the four flatted corners, with a heavy piece of paper between it and the frame. The silver coating on the back of the mirror is covered by a layer of what looks like brass or aluminium foil. |
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