Abstract: Apparatus used for the directional surveying of deep wells, i.e., 20,000-25,000 feet (6,096 meters-7,620 meters), and which is specifically identified as a gyroscopic directional surveying instrument having a high pressure and a high temperature capability, e.g., 24,000 pounds per square inch (1,632.65 atmospheres) and 450.degree. F. (232.22.degree. C.). While in its fully assembled configuration, the apparatus may be described as being exceptionally long (or at times unwieldy), e.g., 12-16 feet long (3.66 meters-4.88 meters), it is quite remarkable that it does not exceed three inches (76.2 millimeters) in diameter. Therefore, it may readily be lowered into the small diameter steel casing normally defining the walls of these deep wells. In view of its cumbersomeness, it is significant to note that the apparatus may readily be broken-down into upper and lower sub-assemblies when being transported to or from the well site.