Patent GB-831066-A (GB)
Title: A logarithmic computing device
IPC: G06G1/00
Filed: 1956-02-27
Abstract: 831,066. Calculating-apparatus. ARICI, G. Feb. 27, 1956 [March 4, 1955], No. 6063/56. Class 106 (1). A logarithmic device, more particularly for making calculations relating to reinforced concrete, comprises members which bear scales and indices for co-operation with the scales and are rotatable about more than one axis, and certain of which members are coupled to others either permanently or selectively for movement together. The device, when set in accordance with certain data, enables the whole range of possible values of other factors to be examined. Rotation of a knob 1, Figs. 2 and 6, through gears 2 and 3 rotates a cursor ir and, by means of mating friction cones 5, 6 and gear 7, rotates a scale r to the same extent. The cursor ir and scale r are carried by concentric hollow shafts. The cursor and its shaft have mating conical. surfaces to permit of accurate initial adjustment after which they are clamped together by a nut 70. On depression of the knob 1 against a spring 4, the cone 6 is disengaged and the knob 1 no longer rotates the scale r. A collar 62 beneath the knob 1 at the same time depresses a spring blade 64 which presses a rubber disc 66 against nuts 68 fast with the cone 6 which is thus held against movement. A cursor it and cooperating scale t are rotatable in a similar manner by a knob 46 through gears 37 and 32, Fig. 1, respectively. A further knob 47, Fig. 4, is coupled by gears 21 and 22 and a central shaft 23 to a cursor ip and, when undepressed, by gears 15, 14 to a member 17 bearing a scale d. The gears 3 and 14 mesh with one another, while a gear 13, fast with a scale M associated with a fixed cursor iM, meshes directly with the gear 7 and via an idler pinion (not shown) with the gear 32. The gear 37 meshes with a gear 42 fast with a scale As. The sleeves connecting the gears 42, 14 and 13 with their respective scales As, d and M are mounted concentrically about the shaft 23 together with a fixed sleeve 25 carrying a box 27 bearing a scale u. A scale b together with a cursor member ik are secured to a ring 30, Fig. 7, which rotates with a ring 28 by virtue of a pin 79 engaging in a hole in the latter. The ring 28 normally presses radially outwards on to the box 27 and so is normally held stationary, but it is split and formed with radial slots so as to enable it to be contracted to engage instead a ring 29 secured for rotation with the cursor ip. The ring 28 is contracted by the rocking of an arm 53 engaging pins 55 on either side of the split. The arm 53 carries a roller 54 which may be engaged by an inward projection 59 of a ring 57 on rotation of the latter by the engagement of a stylus in a portion 58. A pin 60 projecting inwardly from the ring 57 through a slot 81 in the box 27 and into a recess 83 in the ring 28 co-operates with a ball 61 in an aperture of the ring 28 and the ball cooperates with a hole 82 in the box 27 in such a manner that the ring 28 can only be unlocked from the ring 29 and cursor ip and locked to the stationary box 27 in a predetermined position. Rotatable within the member 17, Fig. 4, bearing the scale d, by means of a knob 48, is a ring 50 bearing a scale kd and a cursor is, Fig. 6, cooperating with scales F<SP>1</SP>, k and Cr marked on the member 17. When this ring is set according to k, kd may be read simultaneously with d. The cursor ip, Fig. 7, also bears a simple scale by which a cursor iN may be set. The scale As may then be read by the cursor iN instead of the cursor ip to give a value Av proportional to As. Other factors may similarly be introduced by means of a further cursor iU bearing two cursor lines and settable by means of a scale a on the cursor iN. The scales r and t are drawn in multiple for various conditions and to extend the range further, the cursors ir and it each bear three cursor lines, values being mentally halved or doubled for the outer lines. A further conversion is facilitated by straight scales k read by a cursor ik bearing three columns of values, the outer ones requiring a mental halving or doubling. Additional straight scales F<SP>1</SP>, Cr are used in association with the circular scales F<SP>1</SP>, Cr. The cursor iM may be provided with two cursor lines to enable readings to be taken in alternative systems of units.