The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 03, 1978
Filed:
May. 04, 1976
Applicant:
Inventor:
John M Waters, Derby, EN;
Assignee:
British Railways Board, London, EN;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
E01B / ;
U.S. Cl.
CPC ...
33287 ; 404 84 ; 104 / ;
Abstract
An optical system for establishing a reference datum in relation to which operations can be carried out in roadway workings comprises optical devices which define an optical triangle whose plane inclines downwardly towards the plane of the roadway. The inclination of the plane of the optical triangle is adjustable so that a corner of the triangle is set at the level of the roadway as determined by a reflected image of the roadway surface.