| 摘要 |
The invention relates to an improvement in stopping apparatus permitting boreholes to be made with great accuracy and requiring little manpower attendance, said apparatus comprising a movable platform with lifting jacks thereon for fixing it in a horizontal position, and a plurality of arms each of which is articulated to a central stud on the platform, is swingable in a substantially horizontal plane, is adapted for carrying drilling means and comprises two telescopic parts with means for locking said parts in selected positions relatively to each other and for indicating the degree of their relative telescopic displacement.
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