583,637. Slide-rules. SNODGRASS, B. Nov. 10, 1944, No. 22171. [Class 106 (i)] A cursor for a flat straight type slide-rule k has means whereby it is held in any set position thereon comprising a bow spring a mounted on the inside of a block b in inclined slots d having g limited clearances therein to prevent one end from escaping should the other shift to the base of its slot. The other side block j may be recessed to leave lands n at each end which together with the crown of the bow spring will then form a three-point contact between the cursor and the slide-rule.