Patent GB-188851-A (GB)
Title: Improvements in and relating to surveying instruments or the like
IPC: G01C5/00
Filed: 1921-09-21
Abstract: 188,851. Vaughan, F. E. Sept. 21, 1921. Clinometers. - A sighting-clinometer, for example for use in plane table surveying, comprises a main frame 6, upon which is adjustably supported a bubble tube 21, a sighting device such as a telescope 13 pivotally mounted on the frame to swing in a vertical plane independently of the bubble tube, a graduated arc 18 and a cooperating index such as a vernier 24, the one being mounted to move with the sighting device and the other being rigidly connected to and movable with the bubble tube. The frame 6, which is formed with uprights 9, 10 connected by a cross-piece 11 at the top, is rigidly secured as by screws 8 to a base 5 adapted to be clamped to a base-plate 2 formed with a graduated straight edge 2<a> and carrying a circular level 3 and a trough compass 4. The telescope 13, to which the arc is secured by screws 19, is provided with trunnions 14, 15 formed with conical bearings to receive pivot screws 16, 17 adjustably mounted in the uprights 9, 10. A support 20 mounted to swing on the trunnion 14 carries at its upper end the bubble tube 21 adjustable by screws 22, 23, and at its lower end the vernier 24 disposed against the arc 18. A depending lug 25 secured to the vernier is disposed between a spring-pressed plunger 27 and an adjusting screw 26. The lower portion of the upright 9 is formed as shown in Fig. 1 to facilitate reading of the vernier, and its upper portion is formed with sections 9<a> - - 9<d> extending around the bubble tube. The base 5 is detach ably clamped to the base-plate 2 as follows. A clamping-strip 28 with an undercut bevelled side 28<a> is secured to the plate 2 with the side 28<a> in predetermined relation to the edge 2a, and against this side is placed the correspondinglybevelled side 5a of the base 5, disposed in a predetermined relation the plane of rotation of the sighting-device. The opposite side 5b of tho base 5 is similarly bevelled and a clamping bar 31 is formed with an undercut side 31<a> similarlv bevelled. Holes in the ends of the bar 31 engage screwed studs 29, 30 secured to the plate 2, the thread on the stud 29 being relatively coarse. The stud 30 is fitted with a nut 32 and a locking nut 33, and the stud 29 with a thumb nut 34. The middle portion of the bar 31 is formed with a horizontal recess to receive a block 35 having its exposed face 35<a> bevelled parallel to the side 31a of the bar 31. Screws 36, 37, 38 bear against the back of the block 35 and are adapted to be locked by screws 39, 40, 41 respectively, while other screws 42, 43, 44 serve to clamp the block 35 in adjusted position. The underside of the bar 31 is formed with a slight bevel 31b at its forward end. To adjust the clamp, the screws 39, 40, 41 are loosened, the screws 42, 43, 44 are adjusted to press lightly on the block 35, the screws 36, 37, 38 are loosened, and the block 35 is pressed back into its slot. The instrument is then set up as in Fig. 1, the nut 32 is screwed down firmly, and the nut 34 is screwed down to bear lightly on the bar 31. The screws 36, 37, 38 are then tightened to press the block 35 firmly against the base 5, nuts 32, 34, and the bar 31 are removed, and the screws 39 - - 44 are tightened. The bar 31 is then replaced, the nuts 32, 33 are screwed into position, and the nut 34 is screwed down and then loosened by a single back turn.