DANGER TO EYES

Evening Post, Volume CXXII, Issue 138, 8 December 1936, Page 12

DANGER TO EYES

IN WATCHING ECLIPSE

PROTECTION NEEDED

ADVICE TO OBSERVERS

What sort of spectacle the eclip: x of the sun will be on Monday mornin g next depends- entirely upon the we; a ther. The eclipse, one may be sur 3 will take place whatever the weathc , conditions, but if it is a fine mornin " the phenomenon will be one of ver £ great interest. In-the zone where tl: ■- eclipse is an annular one the phem '<• menon will be'of greatest interest, bi 11 even in Wellington, where the eolips £ is only a partial one, it can hard! f escape anybody's notice as nearly mm 1 tenths of the sun will be obscured. I Common sense suggests that to ol r serve the eclipse some means will hay to be taken to. counteract the glare c 5 the sun. It is impossible to gaze ; the sun if it is shining in all its glor I 1 without injury to the eyes: to attemj *I to do so is a sure way to ruin one 31 eyesight; temporarily or permanentl; "! smoked glass suggests itself as ' medium through which the sun may b ' observed with impunity. But smoke glass has its drawbacks, one bein " that the spot is apt to rub off ver I easily and to blacken the observer ' face. This can be overcome by smbl " ing two pieces of glass and bindin » them together so that the two smoke 5 sides are together. An improvement on smoked glas for eclipse observation is photographi film or a photographic plate. If this i deliberately fogged and developed unt: black, it makes an excellent trans parent medium through which to.vicv the sun. If the density of the blacli ness is varied, all the better, then tha part of the film or plate can be lookei through which best suits the condition prevailing. AVOIDING A STIFF NECK. . But gazing at the sun either througl smoked glass or photographic plate or films, if indulged in for any lengtl of time, is likely to result in a stif neck, and the higher the sun climbs ii the heavens the stiffer will the neel become. Those who have the oppoi tunity and leisure can observe th< eclipse sitting down in comfort am without straining the neck at awkwari angles. The only apparatus requirei is a bucket of water placed in such ; position that its surface is not rufflei by any passing breeze. The observe: seats himself or herself so that thi reflection of the sun can be seen in thi water, and the whole process of thi eclipse can then be seen, in comfort Much of the sun's heat is absorbed hi the water, and its intensity i: diminished in the reflected image. Evei then some protection may be needec for the eyes, but any risk of injury i: greatly diminished. Another possible way of observing the eclipse without risk to the eyes is by the use of a piece of cardboard pierced with a small hole, after the manner of the pin-hole camera. The cardboard is held in such a position that the sun shines through the hole : and if a piece of white paper is added to the apparatus, on the latter can be focused a diminutive image of the sun minus all glare. The passage of the moon across the face of the sun can then be observed and the progress oi the eclipse watched. Anyone foolish enough to attempt to use ordinary field glasses or a telescope through which to observe the eclipse, unless- the instrument happens to' be one specially adapted,for solar observation, is taking the direct road for qualification for admission to the Jubilee Institute for the Blind, and warnings against attempting to gaze at the sun with the naked and unprotected eye cannot be too insistent. It would be a good plan between now and Monday next, at any time during which the sun condescends to shine, to practise whatever method of observation it is intended to use, so that when the eclipse actually occurs there will be no disappointment owing to the failure of the method adopted. Astronomers with their numerous instruments and gadgets have been practising hard at all favourable opportunities during the last week or ten days so as to leave nothing to chance on the morning of December 14.