Early Technology: Herschal Type Astronomical Telescope late eighteenth century

Fine Herschel type Newtonian astronomical telescope with an octagonal wood barrel 54" (137 cm) long 6.75" (17 cm) diameter. The wood 'lens cap' has a removable centre for stopping down the aperture. At some point the outer doughnut ring of the lens cap has been broken in two and has been somewhat clumsily glued back together. (This could be easily re-done for a modest amount by any competent cabinet maker). At the base is the polished metal speculum 5.25" ( 13.3 cm) diameter protected by a brass lens cap. It is in fine condition. On the side below the eyepiece is a brass inclinometer with a glass bubble for measuring the angle of elevation on an arc with a range of 0º - 105º with a vernier scale. There are four eyepieces ranging in power, plus two dark filters. All appear to be original and fit in the triangular section housed in the stand. One lens, the second most powerful has a scratch or crack - not sure which - on the outer seed sized lens, the others are all in good condition. When empty the eyepiece tube is plugged with a brass cap. The small front mirror is protected by another brass cover and is also in fine condition. Mounted on the side is a small brass refractor sighting telescope. The telescope tube is mounted on a triangular wood frame with a caster on the front foot. The elevation is effected by a round wood strut with a longitudinal brass inset and held in position by a nulled brass screw. Lateral movement is accomplished by turning the brass sickle shaped handle at the front which turns a long brass screw thread. A triangular cover reveals the spare lenses set into a tray. The bottom hole at the front is larger to enable the operator to remove the lens tray for easy access to alternative lenses. The stand is in remarkable original condition. I can detect no repairs to it and the patina is excellent. At the base the stand is 30" (76 cm) from front to back. The width of the two rear legs is 27.5" (70 cm). The height to the triangular lens drawer is 30" (76 cm). At bottom elevation the height to the top of the telescope barrel is 43" (109 cm). The telescope barrel is in fine condition for its age, again no detectable repairs but there are two small screw holes at the top very near the front. Obviously at some point in its history someone thought it was a good idea to be able to retain the dust cap in place by the insertion of two small screws. The screws holding the mountings of the sighting telescope to the large telescope barrel are not original. All in all this telescope is in a very clean original condition, quite exceptionally so considering its age, which I would put between 1795 and 1810. It is British but not signed, which is not unusual for such a piece. I have never used a similar instrument previously, but when I set it up the first thing which appeared was a horizontal black line, which when brought into focus was seen to be one of the high tension electricity cables some distance off from my house across a field. The instrument was so fine and powerful that I could see the individual twisted metal strands of the cable very clearly. I was, to coin a phrase, quite bowled over that an instrument of this age worked so brilliantly. It is much brighter than any of the smaller brass reflecting telescopes that have been through my hand in the past. Call me biased but I think this is a really wonderful object. Packing free, transport and insurance at cost.

Herschal Type Astronomical Telescope late eighteenth century

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