73019596
Apr 24, 1974
Apr 27, 1976
APPARATUS FOR USE IN CONNECTION WITH THE LAYING OF UNDERGROUND PIPELINES-NAMELY, LASER BEAM PROJECTORS, TARGETS UTILIZED WITH SAID PROJECTORS, GRADE DETERMINING DEVICES, BLOWERS, AND HARDWARE FOR MOUNTING ALL OF THE ABOVE COMPONENTS IN PREDETERMINED RELATIONSHIP TO EACH OTHER
Electrical and Scientific Apparatus