262 KEPORT — 1881. 



• The details in this table show that the distance at which the dots 

 could be counted by those under 25 years of age in Class I. was about 

 half that found for each of the other four classes, while above 25 this 

 difference was greatly reduced. This discrepancy has arisen from the 

 persons in Class I. having been examined in a hall where the space was 

 limited and the light not very good ; but it is so great as to prevent the 

 numbers for the first class being combined with those for the other four 

 in a general mean ; consequently the latter only, which are sufiiciently 

 regular among themselves to justify the proceeding, have been employed 

 for this purpose, and the results are given in the 6th column of the 

 table. From this it appears that, in a mixed town and country popula- 

 tion of 974, those from 15 to 19 could distinguish the test-dots at a mean 

 distance of 53'7 feet; this diminished through 51"7 feet between 20 and 

 24, to 50'0 feet from 30 to 39 ; a decrease of 2 feet in ten years went on 

 from 40 to 59 ; and after 60 this was nearly doubled. There is here 

 an approximate measure of the reduction of the range of vision with 

 advancing age, which, taking the distance the dots were visible from 

 15 to 19 as the unit, may be represented for the subsequent ages as 

 follow : — 



Ages . . 15- 20- 25- 30- 40- 60- 60- 



Kange of vision 1 -96 -93 -93 -89 -86 -74 



The influence of town or country occupations and surroundings may 

 now be examined. Class III. may be taken to represent the latter, but 

 it is advisable to combine Classes IV. and V., to increase the number as 

 well as to embrace a greater variety of occupations, to illustrate the 

 former. The results are given in the last column in the above, table. 

 Class II. includes persons in a difi'erent sphere of life from III., IV., 

 and v., and their numbers are too few at present to afford a suflBcient 

 basis to work on ; while Class I., as has been already mentioned, is not 

 available. Taking the mean distance at which the dots were distinguished 

 at 15 to 19 as the unit as above, the ranges at subsequent ages were as 

 follow : — 



Though Class III. embi'aces 412 individuals, it is evident from the 

 course of the ratios from the ages of 30 to 59 that they are not suffi. 

 ciently numerous to neutralise irregular fluctuations ; nevertheless, when 

 compared with those for Classes IV. and V. in the next line, there can 

 be no doubt that country life and occupations are far less injurious to 

 vision as age advances than residence in towns with its concomitant cir- 

 cumstances. As the smaller distance at which the dots were distinguished 

 by persons under 19 in the towns than in the country may be due in a 

 great measure to the difference in the brightness of illumination in these 

 positions, it is prudent to postpone the consideration of how far people at 

 that age have their vision afiected by town life until suSicient material 

 be accumulated. These facts will be readily appreciated by examining the 

 diagram on Plate IV. 



These remarks will afford a fair idea of the scope of the present 

 inquiry ; but many more observations, especially at the higher ages, are 

 required to place the results on a fii-mer basis. With a sufficient number 

 of observations the influence of any single occuj^ation, or of a series of 



