# US 4,395,828 A · Combination geodetic transit compass and signal mirror

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,395,828 A
- Document ID: US4395828A
- Status: Granted
- Kind: A
- Application number: 06/168,246
- Filed: 1980-07-10
- Granted: 1983-08-02
- Earliest claimed: 1980-07-10
- Assignees: Texasgulf Inc.
- Inventors: Allan P. Juhas
- Web page: https://patentgrep.com/patent/US4395828A

## CPC

- G01C 17/20: Observing the compass card or needle
- G01C 17/04: with north-seeking magnetic elements, e.g. needles
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## Abstract

A geodetic compass having a mirrored cover that has the dual purpose of providing means for reading the compass needle orientation for geodetic purposes, while at the same time having cross hatch diffractional sighting means incorporated in said cover and mirror for utilizing said mirror for emergency signalling purposes.

## Claims

### Claim 1

A geodetic compass and signal device comprising
a base member housing a rotatable magnetic compass needle and including a calibrated peripheral scale;
a cover hinged to said base member, said cover including a front sight means having a sighting aperture, a mirror in facing relation to the compass needle, an aperture extending through said mirror and said cover, and a rectangular mesh diffraction grid in said aperture for reflective alignment of said mirror with a distant target for signalling purposes; and
a rear sight means hingedly connected to said base member opposite said cover, said rear sight means including a sighting means and an elongated opening therein for reading of said compass needle in said mirror for sighting purposes.

### Claim 2 (depends on 1)

The device as set forth in claim 1 wherein said grid is a light diffractive rectangular wire grid and which further comprises a transparent protective lid overlying said grid on the outside of said cover.

### Claim 3 (depends on 1)

The device as set forth in claim 1 wherein said grid has a flat annular shape with a centrally disposed sighting hole in the center thereof.

### Claim 4 (depends on 3)

The device as set forth in claim 3 wherein said apertured portion is offset from the geometric center of said mirror.

### Claim 5 (depends on 4)

The device as set forth in claim 4 wherein said grid is comprised of a stainless steel wire screen of about a 40 mesh size and said lid is glass.