SUN GLARE

Wairarapa Times-Age, 9 February 1940, Page 8

SUN GLARE

SELECTION OF SUITABLE GLASSES. LIGHT OFTEN TROUBLESOME. There are many factors which govern the degree of comfort in a car trip; there's the ear. the road, the weather and. amongst a host of other conditions the light. Glaring light reflected from the various types of road surfaces takes much of the pleasure out of car driving. For drivers and passengers too, it creates a sensation of fatigue. Added to this glare is the strain caused by quickly passing objects, necessitating rapid eye adjustments: there is extra intentness c£ seeing and the continual strain to see as much as possible as quickly as possible. These arc contributing factors which place our eyes on the peak load when driving. There is little or no chance for relaxation and. in consideration of this, it behoves us to take whatever steps are possible lo relieve < ur eyes: they should be afforded some protection, either by means of properly prescribed spectacles or correctly designed sun-glasses. In the matter of sun glasses and their selection, every care should be exercised to see that these have perfectly ■ plane" lenses of the optically ground type. There are two principal factors to be considered. Firstly the quality of the glass and secondly its colour. GOOD GLASS ESSENTIAL. Lenses should be free from any aberrations or flaws, and this can only be assured -by the use of high quality optical glass which must have its surfaces ground and polished perfectly plane. The cheaper or rolled types are full of imperfections due to unevenness in the mixture of the glass, and to undulations of the surfaces. Such imperfections affect the vision and can only be compensated for by eye-strain, causing more aggravation than relief. There is as much difference between the ground and rolled lenses as between the plate glass in your windshield and the ordinary window glass as fitted to a greenhouse. A simple test will reveal the bad type. Hold the glasses at a distance of about ten inches from the eye and, looking through the lens, view the cross bars of a window or some similar object situated about twenty or thirty feet away. Now move the lens up and down, then across from side to side, watching the cross bars meanwhile. If there is any apparent movement. jumping or distortion of the bars, the lenses are imperfect and should be rejected. From observation of the sun glasses worn by motorists and picnickers, etc, it is evident that there is a tendency to wear too dark a tint. Glasses so dark that the wearers’ eyes cannot be seen through them are absolutely unnecessary for the conditions met with in New Zealand, and may do more harm than good. Even under glaring conditions a mild tint will make all the difference between comfort and discomfort. Vivid colours should be avoided, preference being given to the neutral or smoke tints. These have the effect of reducing the glare without altering colour values. The late Sir William Crookes, a famous English scientist, designed a series of tints now known by his name. This series has the effect of eliminating the harmful part of light without reducing visibility. Unfortunately modern commercialism has prostituted the reputation of genuine Crookes glass. Whereas this name was originally synonymous with perfect quality lenses, cheap manufacturers have copied the tint but not the quality.