Transactions . ripod-head, and says it is theirinvention. It is, however, essentially Edmund Drapers shitt-ing tripod-head, with the addition of a clamping-plate to adaptit to use with three leveling-screws. Within a vear after Youngin 1858 patented the shifting tripod-head now claimed by Hul- * Remarks on Mine-Surveying Instruments, Trans., xxxi., 31. 94 NOTES ON MINK-SURVKYIN<; INSTRUMENTS. berl as hie own suggestion to Young, Draper, to attain thehighly important object of the device and ye1 to avoid infring-ing upon Youngs patent, wry ingeniously contrived his ownnut hod, hut did not ha
Transactions . ripod-head, and says it is theirinvention. It is, however, essentially Edmund Drapers shitt-ing tripod-head, with the addition of a clamping-plate to adaptit to use with three leveling-screws. Within a vear after Youngin 1858 patented the shifting tripod-head now claimed by Hul- * Remarks on Mine-Surveying Instruments, Trans., xxxi., 31. 94 NOTES ON MINK-SURVKYIN<; INSTRUMENTS. berl as hie own suggestion to Young, Draper, to attain thehighly important object of the device and ye1 to avoid infring-ing upon Youngs patent, wry ingeniously contrived his ownnut hod, hut did not have it patented. It is shown in Fig. are two horizontal brass plates, about 4 in. by 8 in.,large enough to give great stability, the lower plate fixed uponthe top of the tripod, and the upper or shifting-plate capableof moving in any direction upon the lower one, within a radiusof about an inch, hut restrained from wider movement by asmall pin in a narrow slot near each end of each plate, the Fro. Drapers Shifting Tripod-Head, with One Nut Removed. slots ot one plate at right angles to those of the other. Thepins have a shoulder at the bottom and a screw-thread on theirupper part, and the plates may be clamped together by a milled-head nut on each pin. The ball-socket is a part of the upperplate at its center. Upon the upper or shifting-plate rest thefour leveling-screws. Drapers tripod-head has a larger move-ment than Youngs, and in spite of its bulkier form is still pre-ferred by some engineers, and is still manufactured. Its mainobjections are that the clamping-screws are liable to get lost inthe field, and the large plates to get slightly bent and conse-quently useless. NOTi> OH KINB-8URVBYING [N8TRUM1NT8. 1864, Mr. Chaa. 8. Heller (no* of Heller A Brightly)contrived a shifting tripod-head, still in use, that is readily ;i| »-plicable to any old instrument, and precisely similar in princi-ple to Mr. Eloskolds tripod-head of L866.* A 1 ;r;ida
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
