194 



KNOW^LEDGE • 



[March 30, 1883. 



As soon as it is found tliat the figure 3 cannot be dis- 

 tinguishrd from 5 in tli« popular railway guide by artificial 

 light, spt'ctacles should at once bo obtained. 



A worse mistake than postponing getting a pair of 

 spectacles 3uitc<l to their own sight, is to use their father's 

 or mothers spectacles, if they liave such by them. By 

 doing this, they may in a few months age their eyes as 

 mucli as with the use of proper spectacles they would have 

 aged in as many years. 



These remarks apply quite as much to i;f ntlemen as to 

 ladies. 



Another mistake, commonly made by short-sighted 

 persons, is wearing the same spectacles for reading and 

 walking. This can seldom be done without straining tli" 

 eyes. 



Nearly all short-sighted persons require two pairs of 

 spectacles, and these often differ widely in focus. Occa- 

 sionally those suited for reading require to be only half the 

 focus of those suitable for walking. 



At times the power of accommodation is so deficient 

 that three pairs of spectacles are required to see objects 

 at different distances, say, from reading-distance to the 

 horizon. 



Different spectacles should, as a rule, always be worn for 

 playing music to those used for reading. 



Although, of course, the power of adapting the vision or 

 seeing clearly is, as a rule, first lost for close objects, j-et 

 occasionally it is first lost for distant objects. 



I have known persons who fancied that their eyesight 

 was seriously and permanently impaired from being 

 unaware of this fact. 



A pair of short-sighted spectacles gave them clear vision 

 directly. 



No attention is generally paid to a pair of spectacles 

 fitting the face, yet, to obtain the full benefit from them, 

 they ought to fit the wearer's fiace so well that the centres 

 of the glasses come exactly opposite to the pupils of the 

 eyes. It is curious that people who would never think of 

 wearing a dress or coat unless it fitted them, will wear any 

 pair of spectacles, though the result is more disfiguring 

 and often injurious to the eyes. It is necessary to keep at 

 least seven different patterns of spectacles to select from, 

 and even then spectacles must often be made to fit the 

 face, and this should really add very little to their cost. If 

 the spectacles are either too wide or too narrow, as shown 

 in the diagrams, they have a tendency to produce double- 

 vision, that is, to make every object appear to be doubled. 

 In Fig. G the spectacles are too wide ; in Fig. 7 they are 

 too narrow, and in Fig. t^ they are the correct width. 



Two things I must earnestly warn you never to do. Never 

 use a single eye-glass (Fig. '.)), and never keep a pair of 

 spectacles on your face that are suited for reading when 

 you are walking about, or, in fact, one moment after you 

 have done looking ^^ some near object through them. 



While I was reading this for the press I received a 

 letter from a lady who had fallen down stairs in her 

 spectacles and broken them. Most likely the spectacles 

 were the rruisf of the accident 



Very recently I saw a gentleman in the Charing-cro.S3 

 Railway Station \\earing a pair of reading spectacles. 

 With these on he was trying to make out the time by the 

 station clock. This clock must be about thirty or forty 

 feet high, and he was straining his eyes to see it through 

 a pair of spectacles which would not show any object 

 clearly at a greater distance than eighteen inches. 



By wearing them he was seriously injuring his eyes, and 

 risking an accident in getting in and out of the railway 

 carriages. Fig. 10 illustrates me effect of a person looking 

 at a church clock under similar conditions. 



r^^^ 





Fig. 10. 



I have traced many accidents to persons who were Ion;? 

 sighted keeping on their spectacles when going down stairs. 



(To be C07itinued.) 



TuK Electric Licht in Switzerland. — .\ DaUii Xetc& 

 correspondent says that a scheme is proposed for lighting 

 the whole of the Canton of Yaud by electricity. The 

 motive force w^ould be derived from turbines of .'),00O 

 horse-power at N'allorbes, and, the water supply being conr 

 stant and abundant, it is believed that gas, which is very 

 costly in Switzerland, may be entirely dispensed with 

 throughout the district 



