MEASURING LIGHT.

Auckland Star, Volume LXIX, Issue 79, 4 April 1938, Page 5

MEASURING LIGHT.

TO SAFEGUARD EYES. SPECIAL INSTRUMENTS. SUPER-SENSITIVE TYPE. (Hy Telegraph.—Own Orro>iiomlent.) WEFJJNGTOX, this day. ' In America the eye.-iglu it- carefully safeguarded by the adjustment of all artificial light. ' In New Zealand the' >ame care ir- not exercised. People . read, write and work in all kinrU of liglit, iirer-pecthe of their strength or the direction of the beam, and then ' wonder why it i> that they ha\e to get ; j;la>>e> while riim]iiirnti\ely yming. I he adjustment of light to .»uit the cye.-ight', lia> lieciime almc-t an exact science in; the I'uited State-, and optical instru-j ments of a c-nppr->eii>ithe chara.-ter have been invented to measure lia'ht. in. the open or under cover, t>. determine exactly its strength and to what extent' work of any kind may be done under it. ! say* the " Dominion." The electricity department of the Wellington ( itv Corporation has, imported some of the*e instruments.'' and ir- now in a position to sne ad\ire as to the strength and disposition of the lights in the home, the factory, ship, the counting house or the* warehouse: indeed, wherever light in. used. These instruments are dete-Mors. Thev .-how at once the mea.-ure of light thati is being sained from any window or "le.'tri.' lamp for lamp*).' and. from a knowledge of what is required in to work to the fullest advantage with-' out eye-strain, the .officials are able to -ay whether this room or that faetorvi is properly lislited. ' , This IP not a matter of selling more current or more limps. Tt is Mmply a mean? of acquainting w i ip peoule with the conditions that exist in their ho m es i or offices, and telling them at the same time whether tho-e conditions are in conformity with the principles laid down for the preservation of the eve- : agn*- • j

! " : What Measure Means. ' J There is a definite measure of light called the "foot candle."' .Tus-t as one measures liquid In the pint or quart, "lie can measure' light by the "foot candle."' That measure ' means the .amount of light given hy a single candle "ii an object placed a foot away from ;the flame. i Mo.-t people woulil <-hudder at the' thought of reading or performing other : \isual tasks one foot away from an ordinary candle, yet plenty of people do ibis e\en under modern efficient ami convenient electric light. Everywhere ; throughout the world, hy day ami night. .millions of ppople read and work under intensities- of illumination !c-> than one foot candle, and .-on-ider they are doing .nothing wrong, aet ordinary sunlight in mid-day measurer, ln.nno foot candles. jHin] tlie light under the shade of a tree i- often 10-00 foot , andW. Pγ. Matthew I.uckiesh. who has studied the intensely. state> ■ that for rending, writing, drafting.' machine work and watch repairing, the: flighting should ho of from r>o to 100 foot ;candle>: clerical work from 20 to .'.O |foot candles: for moderate and pro-! jlnnged task- of offi.e work, and unrro- . longed scwino and lending from 10 to j2O foot candies: and for casual work more or less interrupted. Dr. Luckiesh i*«»ts down the light requirement as from five to 10 foot randies.