dip circle
Date: circa 1835
Inventory Number: 1990-2-0001a
Classification: Dip Needle
Subject:
Maker: Henri Gambey (1787 - 1847)
Cultural Region:
Place of Origin:
Dimensions:
25.8 × 21.2 × 17.6 cm (10 3/16 × 8 3/8 × 6 15/16 in.)
Accessories: cover (square wood frame with glass panes); spare needle in separate box stamped "8-22" (Inv # 1990-2-0001b)
Description:
A two-sided metal pointer pivoted at the center of a graduated metal circle mounted upright on a rotable base on a horizontal circle with a degree scale and a vernier.This rotable base has a spirit level.
The whole ensemble is supported by a brass tripod base with levelling screws.
The instrument includes a square frame with glass covering both sides, to be secured over the rotable base to cover the vertical circle.
The whole ensemble is supported by a brass tripod base with levelling screws.
The instrument includes a square frame with glass covering both sides, to be secured over the rotable base to cover the vertical circle.
Signedengraved on brass plate at bottom of needle box: Gambey a Paris
Inscribedon top of object in white paint: MA1
FunctionA dip needle is used to indicate the inclination of the earth's magnetic field relative to the earth's surface. This particular one gives very precise readings of both the horizontal and vertical directions of the earth's magnetic field, having two scales. It can be covered during use to reduce outside disturbances.