THE PROBLME OF GLARE

Wanganui Chronicle, Volume 79, Issue 123, 26 May 1936, Page 5

THE PROBLME OF GLARE

OVERCOMING DAZZLE DANGERS OF DRIVING AT NIGHT POSSIBLE REMDD._S Il would surprise many drivers, L they gave luuugut to Luu paWOicm, Lu nonce. how e.xLraoruiuaii.y puui a standard uf neutl-iamp adj—aimciu seems to satisfy a large percc.xLugj 01 motorists, writes Uiuiussur A. Ji. j_.uw in the JiAOtur. On any main ro<?u it is possible to watch uncoiuiug cars with tneir ueud-lauip beams putting skywards, flickering sideways, crossing each other, auu in general inflicting discomiort upon everyone in thenvicinity. Unfortunately, it is not possible to lay down any definite rule in respect to head-lamps without injustice, ior the excellent reason that one oi the factors in what might be called the “formula” of comiortable vision at night is the human eve. In front of the large globe of the eye is a kind of iris uiaparagm whicn closes to prevent too much light irom reaching tne retina. This “accommodation” io the amount of light which is allowed to pass is different in the ciue of eveiy individual person, as is also the period during which a bright image is retained by tne mosaic system upon which the picture lulls ior transmission to the brain. Effects on the Eyes. The retina is composed of a very large numucr of small divisions, known 41s rods and cones, wirich are sensative to cv.our and to form; the colour-sensi-tive elements are mure abundant al the centre of the eye. The average driver is probably not very interested in these details; he is content if he can use a light of such power as will enable him tu drive al reasonable speeds at night. A large amount of the illumination which he needs is really required to counteract the effect produced by other approaching cars. Their head-lamps cause the mechanism of his eye to cut out much of the light afforded by the lamps of his own car. Floodlighting of Roads. It is probably too much to hope that roads ill be properly floodlit or keros JluminaUd aud a proper proportion <m light directed to Hie roauway rather liian Into the eyes, but if only the proper principles of road illumination could be generally applied the main difficulty might well oe overcome. Ave see objects in a road lit by street lamps, not so much by reflection as by the contrast which they make with tne road surface. The Head-lamp oi a car throws a beam of vastly greater intensity than can bo produced oy the average street lamp, and even a welllit st.ect seldom approaches bad twilight in visibility value. bush a conclusion is important, because those who have looked at a nead-lanip in sunshine will realise how totally inadequate it is by comparison; tuey will appreciate that it one could look at an ordinary waite muslin dress, illuminated to the same intensity as applies in the case o bright daylight, the eyes would be blinded until accommodation had take place This accommodation is by no means instantaneous; indeed witli some people, a comparatively !on„ tin must elapse before vision again uecomes normal. Back Glare from a og. When driving in fog the main difficulty is Hint in. back gate y " nic the light Hom tie nead-lamps m thrown back into tLe eyes ot the urn er exactly as if he were lacing an on coming car. 'l“is eiiect is quite -1 mate iroui that of fog penetration because the glaring rays a.e mainly those of the lioiet ana bine end uf tne spec lr io’ throw a beam with a flat top below the level of other people s eyes so that oncoming drivers 01 1 trians arc not dazzled is not P‘ able in combination with a lu «g ian Every movement ol the car causes t to i it the beam to be deflected an the source of light is so large t at 1 system can be devised whicn combines efficiency from the optical point « View Willi that of low current cousumpOne obvious way of I'eanng wnh this difficulty is to employ the type of lens whicn cuts out the vio.et and the blue but which for the sake ot 6 e eral comfort does not ovcrcolour die rave deflected. Colour bulbs, or filters nwr the bulb , are often ineifet because a very deep colour mud be employed if the distance pa t 01 the beam is to retain its sensible coloia U Tf lights are used which cut off, in so far as is practicable, the top section of the beam, only a litt.e dazz is caused to oncoming t rafa ;> aad . T. driver is not affected by the Luck S1 The careful adoption of these prim ciples enables fog driving to l ‘ l lied out With a degree ot com art which is a revelation to those who have not made the experiment A wide beam can always be employed so t at there is no change of shadow close t the ear as the sector of light pro grosses forwards. The comparative case of night vision obtainable by tne proper combination of lighting and seating position is often a source ot surprise to those who put up with crowded daytime roads rather than conduct a few simple experiments with their own h-ead-lamp adjustment.

made 110. Robins took five for 18. Middlesex in their first innings made 173. Hulme made 59. Amarnath took six wickets for 29.