GB655322A - Improvements in and relating to calculators - Google Patents

Abstract

655,322. Calculating-apparatus. OWEN, H. E. L., and OWEN, R. E. L. Dec. 19, 1947, No. 33586. [Class 106 (i)] To calculate the height of water above a datum line at a given time and place a line B on a pointer 12 is set to join the heights of water above the datum line at low and high tide on two parallel scales set apart a distance representing the tide duration for that place and a line 40 on a cursor D is set against the given time on a time scale appropriate to the duration and divided harmonically and the required height is read off a scale on the cursor D at the point where the lines B and 40 intersect. The pointer 12 is pivoted at its mid-point on a plate 14 secured to a rod adapted to be moved up and down in a slot 24 by a pin projecting through the base 16, while a spring 19 fixed to the plate 14 biasses the pointer 12 into contact with a plate 22 mounted on a rod adapted to be moved up and down in a slot 28 by another pin, thus allowing the pointer to pivot. The cursor D is mounted on a member 36 which slides on a rod 38 and has a pin projecting rearwardly to engage a slotted connecting-member which is pivoted at 50 and has an oval aperture in which moves an eccentric on whose shaft is fixed a milled wheel 48 by means of which the cursor can be shifted laterally. In a modification the time scales are placed to one side of the pointer, say the left, and the scales of heights are marked on the cursor. In use the pointer is set with the left-hand scale at the right-hand end of the time scales and the cursor is then moved to the left to the appropriate time mark when the pointer indicates the required height on the right-hand scale. Adjustments may alternatively be made by quick pitch screws, index lines on transparent parts may replace " straight edges " and vice versa and a recording drum may be provided settable by operations corresponding to the setting of the pointer and cursor.