Galilean telescope (spyglass) with triple achromatic object glass

Galilean telescope (spyglass) with triple achromatic object glass, 4-power eye-piece, in black fish-skin case by Benjamin Martin, London, England, c. 1782. Fitted with slotted bracket for tripod. Lacking the dust-cap for the object glass

Details

Category:
Optics
Object Number:
1918-145
Materials:
copper (alloy), glass, wood (unidentified), paper (fibre product), cardboard and fish skin
Measurements:
object: x 120 mm x , 40 mm,
case: x 120 mm x , 15 mm,
overall weight: x x , , .255kg
type:
telescope - galilean, telescope - terrestrial and telescope - refracting
credit:
Court, Thomas Henry