| 摘要 |
<p>-la- OF INVENTION. A drill hole survey instrument comprising a first pair of inclinometers with sensitive axes that are co-planar and at 90.degree. to each other, mounted at one end of a torsionally rigid member of known length and a second pair of inclinometers similarly mounted at the other end of the rigid member so that when the instrument is vertical the sensitive axes lie in two vertical planes at 90.degree. to each other.</p> |
