GB480112A - Improvements in calculating mechanism for measuring instruments - Google Patents

Abstract

480,112. Integrating-apparatus; sextants. EVERITT, P. F., HUGHES, A..J., and HUGHES & SON, Ltd., H. Aug. 18, 1936, No. 22739. [Class 106 (iv)] [Also in Group XX] A counter is driven from a measuring- instrument and is arranged to show directly the average of a predetermined number of measurements. Thus, if six is the predetermined number of measurements to be made, the counter may be driven from the instrument through gearing having reduction ratio of 1 : 6, or the counter may be driven synchronously with the instrument but be graduated to show readings 1/6 of the normal values. The invention is .shown applied to a sextant comprising a frame 1, handles 2 rotatable about an axis 3 into the dotted position, Fig. 2, an auxiliary telescope 6, shades 8, and a forehead shield 10 for use in stellar observations. The mirror is adjusted by a lever engaging a spiral groove in a drum carrying an evenly-divided scale 14 and having a boss 16 to which is attached a knurled wheel 15 for coarse adjustments. A worm wheel 17 is also mounted on the boss 16 and can be clamped thereto by any one of several screws 18. The worm wheel 17 is driven for fine adjustments by a worm 27 on a shaft 28 connected by bevel gearing 25 to a knurled wheel 24. The bevel gearing 25 also drives a pinion 29, Fig. 5, connected to the counter through gearing giving the required reduction.. The counter wheels are connected by transfer mechanism comprising pins on the wheels engaging pinions 40 on a shaft 41 carried in arms 46 and pressed into operative position by blade springs 48, the shaft and pinions being moved aside by the transfer pins when the counter is zeroized by knob 49. In operation, a rough reading is taken and the scale 14 then turned back to any convenient scale division, an adjustable stop 20 on the frame being set to engage a pin 19 on the wheel 15 at this position. The screw 18 is engaged and the scale 14 is then moved forward to an accurate reading by the fine adjustment knob 24, this movement being transmitted to the counter. The screw 18 is then disengaged, the scale 14 returned to the position determined by the stop 20 and the operation repeated the predetermined number of times. In a modification, Fig. 6, the instrument 53 is set by a micrometer screw 50, 55 driving the counter directly through a clutch 56. The clutch is then disengaged and the instrument returned to the initial position, the clutch re-engaged and another reading is taken. This process is repeated the predetermined number of times, the counter being graduated to indicate directly the predetermined fraction, i.e. the average of the sum of the readings.