DEFT NEEDLEWORK

Dominion, Volume 29, Issue 133, 29 February 1936, Page 18

DEFT NEEDLEWORK

' Queen Mary’s Compass Cards It. is an apparent paradox that the skilful eye of a Glasgow seamstress, Miss Edith Rankin, assisted by two others, helps,to give the new magnetic compasses of the giant Cunard White Star liner Queen Mary their hairline accuracy under all conditions. Ilers is the responsibility of sewing on the flexible compass card strands of silk of the greatest linencss with the utmost possible accuracy, measured in terms of thousandths of an inch. Ships which use compass cards prepared by this shy but very pleasant little lady fly a dozen flags and cover the seven seas. Their captains can attest the phenomenal accuracy of Miss Rankin’s keen eyesight. An almost instinctive sense of just where each strand of silk should be placed, which is part eyesight and part a very developed sense of touch, makes her extremely valuable in Hie preparation of these compasses. The magnetic compasses of the Queen Mary are the last word in their field and are designed on the principles of the late Lord Kelvin, famous Scottish scientist who achieved distinction in several different fields connected with physics. In addition they also embody all the most modern improvements in details which have been perfected by Lord Kelvin’s successors. One example of these improvements is the means taken to overcome or to prevent the car,] of the compass from being disturbed. The card, in the language of compass makers, is that part of the instrument which comprises the all-important magnetic needles which continue to point to the North regardless of the movement of the ship. The card is poised upon a pivot inside the compass bow), which has a glass cover to enable readings to be made. In Hie la lest form of the Kelvin compasses. designed for Hie Queen Mary, rhe compass card is protected against, disturbances by the coach spring form of suspension which is fitted into the ’ pedestal of the compass mid from which the compass bowl bangs. This coach, spring suspension absorbs practically all motions of a disturbing character which might otherwise be communicated to the compass card. The second protective device used is known as the mattress suspension. This is installed inside the coinpass bowl at the base of the pivot upon which the card is poised. This form or suspension derives from the principle that all disturbances of a mechanical nature arc communicated to the card through the stem of the supporting pivot. Accordingly the base of this pivot is fixed upon Hie mattress suspension ami tills suspension is so designed that disturbing motion* of any kind are virtually cut off from reaching the card. The combined effect of these two devices is to ensure perfect steadiness in the card.